tag:blogger.com,1999:blog-81367656356965458932024-03-19T05:27:19.196-04:00As Many Exceptions As RulesA good teacher must know the rules; a good pupil, the exceptions.
- Martin H. FischerAnonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.comBlogger216125tag:blogger.com,1999:blog-8136765635696545893.post-87346335668750630572018-01-25T06:00:00.000-05:002018-01-25T06:00:00.189-05:00Cellular Self-SacrificeBiology Concepts – apoptosis, synthaesthesia, mitochondria
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We often ascribe human traits to objects that do not have thoughts
or feelings of their own. This is called <b style="mso-bidi-font-weight: normal;">anthropomorphism</b>,
and it is hard to go through a day without committing this faux pas. </div>
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<span style="font-size: 10pt;">Anthropomorphism
is difficult thing to avoid. We are thinking </span></div>
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<span style="font-size: 10pt;">beings,
and we look at other organisms as if we were them – </span></div>
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<span style="font-size: 10pt;">so
we assign our thoughts to them. A typical example would be </span></div>
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<span style="font-size: 10pt;">the
belief that bacteria and viruses MEAN to do us harm, they </span></div>
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<span style="font-size: 10pt;">have
an evil intent when the infect us. It’s just not so……. except </span></div>
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<span style="font-size: 10pt;">for
athlete’s foot fungus. If you have had it before, you know that </span></div>
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<span style="font-size: 10pt;">it
means to make your life miserable.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">It is especially difficult</span> to avoid in biology, even scientists will
say that an organism “decides” to do this or an enzyme interacts with a
substrate “in order to” accomplish that – the enzyme doesn’t have an agenda, it
is just chemistry and physics. Assigning feelings or motives to biological
entities is often a way to help explain a concept. As long as everyone agrees
that it is just a technique, I think it’s fine. The problem arises when not
everyone understands that its just a verbal crutch and they start to internalize
it.<br />
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I can think of one case in particular where individual cells of a
multicellular organism seem to be acting with a purpose, even a sense of
altruism. It is called <b style="mso-bidi-font-weight: normal;">apoptosis</b> or <b style="mso-bidi-font-weight: normal;">programmed cell death</b>. In apoptosis (from
Greek meaning, “falling off”) a cell will die “in order to” contribute to the
overall health of the organism. It happens all the time. Autumn is full of
apoptosis, as this is the mechanism of leaves falling, and is where the
original word came from.</div>
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You just had about 1 million of your cells die as a result of
apoptosis! … There! It just happened again! About a million cells/sec “commit
suicide” (there’s some more anthropomorphism) so that you can live. If they
didn’t die, you would.</div>
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It starts early, when you were in your embryonic stage. Your hands
and feet started as single masses, with the bones growing in the appropriate
places, at 48 days the skin covering is them all was one unit, more of a
mitten than a glove.</div>
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<span style="font-size: 10pt;">In
utero, your hands develop with individual fingers, but covered </span></div>
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<span style="font-size: 10pt;">by
tissue all over, then apoptosis divides them into individual </span></div>
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<span style="font-size: 10pt;">fingers.
The same thing happens with your toes…. Unless it doesn’t </span></div>
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<span style="font-size: 10pt;">work
as it should. If it doesn’t, you end up with syndactyly, or fused </span></div>
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<span style="font-size: 10pt;">digits.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Then</span> some of the skin cells between the
digits began to die, and your fingers and toes started to become apparent. Sometimes
the process doesn’t work completely, and people will have webs between their
fingers or toes, or two digits will be fused together completely (<b>syndactyly</b>,
syn = same and dactyl = digit). In the normal case, these skin cells are programmed to die. Why have the cell
in the first place if it just going to die?<br />
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In terms of fetal formation, the cells do serve a purpose when they
are formed, but that purpose is only temporary. However, this is not unlike
many of your adult cells. The cells dying inside you right now probably had a
“job to do,” but now they are worn out and replacements have been made for
them. In essence, most of our cells are temporary.</div>
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Apoptosis is a group of complex mechanisms that allow cells to die
well. We all know about cells that do not die well. If you hit your thumb with
a hammer, you kill a few thousand cells. They tear open and dump their cellular
contents into the tissue around them. This signals a reaction called
<b>inflammation</b> and perhaps a sort of immune response. Inflammation and immune
responses are good at cleaning up the damage, but they can cause damage in the
process. With a million cells dying every second by apoptosis, you would never
survive if every death brought an inflammatory response. </div>
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<span style="font-size: 10pt;">Necrosis
is the cell death with inflammation and tissue </span></div>
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<span style="font-size: 10pt;">destruction.
This is what happens in frostbite. Can you </span></div>
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<span style="font-size: 10pt;">imagine
if you had this sort of reaction when undergoing </span></div>
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<span style="font-size: 10pt;">apoptosis
to make your individual fingers in utero?</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Dying</span> well means cell death without
inflammation. In apoptosis, the mechanisms work to shrink the cell away from
its neighbors but keeps the cell membrane intact for most of the time it is
dying. This prevents the inflammatory response from being jump started.<br />
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Signals from outside the cell can stimulate apoptosis, including
hormones, damaging chemicals, or a loss of innervation. Sometimes it can be as
little as a cell migrating from where it should be; the lack of the proper
neighboring cells triggers the out of place cell to die. These are examples of <b style="mso-bidi-font-weight: normal;">extrinsic<i style="mso-bidi-font-style: normal;"> </i></b>apoptosis. </div>
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But the signal could be <b style="mso-bidi-font-weight: normal;">intrinsic</b>
as well. Signals that come from inside the cell could be DNA damage, too many
oxygen radicals causing damage to proteins, or even that the cell senses it has
been infected by a virus. Viruses turn the cell into a virus factory,
then the cell bursts to release the new viral particles and they go on to infect more
cells. By initiating programmed cell death, no new viruses are made, so no
additional cells will be infected and killed. As Spock would say, "They good of the many outweighs the good of the few, or the one."</div>
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The exceptional part about this process is that the mitochondrion is a crucial instigator in apoptosis. This organelle
that is so crucial for life and so important for giving the cell its energy to
carry out its functions, is one of the main checkpoints and instruments of programmed cell death.</div>
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If the signal for apoptosis comes from within the cell, it results
in a change in the membrane of the mitochondrion, with leakage of a protein
called <b>cytochrome c</b> out into the cytoplasm. Cytochrome c is usually held
within the mitochondrion, so that the apoptosis process is held in check. Once
released, this protein complexes with other proteins to form an <b style="mso-bidi-font-weight: normal;">apoptosome</b>, and this starts a cascade
toward death.</div>
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If the signal comes from outside the cell, many different receptors
and pathways can be involved, but some of these will also affect the
mitochondria. There are competing sets of factors in the cytoplasm, some always
pushing toward cell death while others apoptosis from proceeding. The
delicate balance of the factors that want to disrupt the mitochondrion and
those that want to protect it allows the cell to live in harmony with itself
until there is a reason to die. </div>
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<span style="font-size: 10pt;">This
cartoon is a little detailed, but the take home message </span></div>
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<span style="font-size: 10pt;">is
that many insults can lead to mitochondrial damage </span></div>
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<span style="font-size: 10pt;">(top
arrows) and the damage can lead to several signals </span></div>
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<span style="font-size: 10pt;">for
cell suicide – apotposis (bottom arrows).</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The extrinsic</span> signals can cause the balance to shift
toward mitochondrial leak of cytochrome c. This leads to apoptosome formation,
and this activates <b style="mso-bidi-font-weight: normal;">caspases</b> and
other executioner protein enzymes that will start to destroy the cell from
within. Some enzymes cut up the DNA into small pieces so that it is no longer
functional. Others force the chromatin and nucleus to condense and shrink
(become <b>pyknotic</b>) and stop making ribosomes. Some digest important proteins in
the cytoplasm. The sum total of their actions is a non-functional cell, but one
that is still intact. Over time, the shrunken and dying cell is recognized by
macrophages or other cells that quietly break it up and digest it, all without
causing any inflammation.<br />
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Apoptosis isn’t just for your looks, as in giving you individual
fingers and toes. It plays a role in every system of your body, in other
animals, and even in plants. Plant cells undergo a programmed cell death, but
it is a little different than animal apoptosis because they also have a cell
wall to deal with and they don’t have an immune system to ingest all the dying
cells. And the metamorphosis of caterpillars turning into butterflies and
tadpoles becoming frogs… that couldn’t happen without a lot of apoptosis.</div>
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Your embryonic and juvenile nervous system has millions of neurons
it does not need. The connections between some neurons may not be in accordance
with how humans process signals, and some dying back of processes and cells is
expected (called neural <b>pruning</b>). </div>
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Misplaced connections that do not die from apoptosis can lead to
some interesting results. <b style="mso-bidi-font-weight: normal;">Synaesthesia</b>
is a group of conditions where sensory input is interpreted in more than one
area. For example, if connections between taste and other parts of the brain
are not pruned by apoptosis, some people will taste colors, or names will have
a certain taste. Many <b>synaesthetes</b> (people with synaesthesia) will see number
in their brains as having certain shape or texture. It is believed that most children
have near photographic memories and cross innervations among the senses, but
that the connections for these abilities die back in order to prevent sensory or
memory overload.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjz_1beFuyNl-WCgSDVa_W8D0MdH4U2BqUJhkk1UTy8YRbJmseOWHAll9y4dhGOaj8FCNvhBro5Y5eAbrmdJrHuG804rE9giFrvqg1Rgf6LtX2iM46Yn2V8wErGoFRArb7878RpcTVoKNeA/s1600/5-synesthesia+hugo+heyrman.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="233" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjz_1beFuyNl-WCgSDVa_W8D0MdH4U2BqUJhkk1UTy8YRbJmseOWHAll9y4dhGOaj8FCNvhBro5Y5eAbrmdJrHuG804rE9giFrvqg1Rgf6LtX2iM46Yn2V8wErGoFRArb7878RpcTVoKNeA/s400/5-synesthesia+hugo+heyrman.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">It
is unfortunate that there aren’t very descriptive pictures </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">that
could show what it is like to have synthaesthesia – sure </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">you
can show a colored word or set of
letters, but you don’t </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">get
the idea of what it is to see it in your head when your </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">hear
a letter or word. This chart shows a little of how the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">senses
can be combine, each combination has a name, but I like </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">how
Dr. Hugo Heyrman sums it up – Synesthesia is a love story </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">between
the senses.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">But this</span> is not the only use of apoptosis in the
brain. You have heard the expression, “use it or lose it?” This applies to your
brain as well. Neural connections in the brain that are stimulated by
experiences or thoughts get reinforced, and are less likely to undergo
programmed cell death. Those connections that are not used when young are not
kept; it would be a waste of energy. <br />
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Your immune system also relies on apoptosis. You have T lymphocytes
that are designed to recognize a certain molecule that shouldn’t be in your
body. Each population of T cells recognizes a different potential problem guest
– millions of them in all. But some of the T cells that are made recognize a
particle that looks a lot like one of your own molecules. You don’t want that.</div>
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In your thymus and other places in your body, your T cells go
through a testing process. If they recognize a protein or molecule that isn’t
you, they are allowed to mature and then go out in to the body and patrol for
their particular target. But if they are programmed to recognize something that
is “self” then they are signaled to undergo apoptosis. </div>
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It is a great system and works most of the time, but there are
exceptions. Some “non-self” proteins can mimic “self” proteins, and if you
start to develop an immune response to them, there may be some cross-reaction
with your own cells. Or perhaps some T cells that recognize a “self” protein
don’t undergo apoptosis when they should. These issues can result in autoimmune
diseases – your immune system is attacking you.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFoNVbgc8_xzKhAJlacDuBDpGWTszGoPtTOMuOOfdQF-9-b2zhiZrWjnTr4s7lU5nBQZjccihVxN2MD1COz8XDwaqOp9u2KdsyLCwYjx6XyKGW1fC4cajUDP-ZFgVngHvABeQueVV2CiEu/s1600/6-Cancer+Cell+Apoptosis.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFoNVbgc8_xzKhAJlacDuBDpGWTszGoPtTOMuOOfdQF-9-b2zhiZrWjnTr4s7lU5nBQZjccihVxN2MD1COz8XDwaqOp9u2KdsyLCwYjx6XyKGW1fC4cajUDP-ZFgVngHvABeQueVV2CiEu/s320/6-Cancer+Cell+Apoptosis.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Cancer
is a loss of cell cycle control, including the idea that </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">cells
are meant to die at an appropriate time. The problem </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">is
that there are many ways that a cell can circumvent the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">apoptosis
signals, so you can’t induce apoptosis in all cancer </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">cells
by using just one medicine. Plus, how do you tell the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">cancer
cells to undergo programmed cell death, </span><br />
<span style="font-size: 10pt;">but tell the normal cells to stay alive?</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">So - too</span> little apoptosis can be a bad thing.
One other big example of this is cancer. Most cells have a life span, they
should die at some point. But in some types of cancer, the mutations can tip
the balance in the cell and mitochondria toward the survival end; they keep
living and dividing and piling up; this is a tumor.<br />
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Death is a part of life, and we should be thankful for it. </div>
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<br /></div>
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<br />
<br />
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Neuropsychology&rft_id=info%3Adoi%2F10.1111%2Fj.1748-6653.2011.02015.x&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Is+synaesthesia+one+condition+or+many%3F+A+large-scale+analysis+reveals+subgroups&rft.issn=17486645&rft.date=2011&rft.volume=5&rft.issue=2&rft.spage=353&rft.epage=371&rft.artnum=http%3A%2F%2Fdoi.wiley.com%2F10.1111%2Fj.1748-6653.2011.02015.x&rft.au=Novich%2C+S.&rft.au=Cheng%2C+S.&rft.au=Eagleman%2C+D.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CNeurology%2C+Pathology%2C+Physiology%2C+Anatomy%2C+Biochemistry%2C+Molecular+Biology">Novich, S., Cheng, S., & Eagleman, D. (2011). Is synaesthesia one condition or many? A large-scale analysis reveals subgroups <span style="font-style: italic;">Journal of Neuropsychology, 5</span> (2), 353-371 DOI: <a href="http://dx.doi.org/10.1111/j.1748-6653.2011.02015.x" rev="review">10.1111/j.1748-6653.2011.02015.x</a></span>
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=NeuroImage&rft_id=info%3Adoi%2F10.1016%2Fj.neuroimage.2008.07.018&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=The+multiple+synaesthete+E.S.+%E2%80%94+Neuroanatomical+basis+of+interval-taste+and+tone-colour+synaesthesia&rft.issn=10538119&rft.date=2008&rft.volume=43&rft.issue=2&rft.spage=192&rft.epage=203&rft.artnum=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1053811908008227&rft.au=H%C3%A4nggi%2C+J.&rft.au=Beeli%2C+G.&rft.au=Oechslin%2C+M.&rft.au=J%C3%A4ncke%2C+L.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CNeuroscience%2CBehavioral+Neuroscience%2C+Cognitive+Neuroscience%2C+Molecular+Neuroscience%2C+Anatomy%2C+Behavioral+Biology%2C+Biochemistry%2C+Cell+Biology%2C+Molecular+Biology">Hänggi, J., Beeli, G., Oechslin, M., & Jäncke, L. (2008). The multiple synaesthete E.S. — Neuroanatomical basis of interval-taste and tone-colour synaesthesia <span style="font-style: italic;">NeuroImage, 43</span> (2), 192-203 DOI: <a href="http://dx.doi.org/10.1016/j.neuroimage.2008.07.018" rev="review">10.1016/j.neuroimage.2008.07.018</a></span>
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Cell+death+and+differentiation&rft_id=info%3Apmid%2F27177021&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Your+neighbours+matter+-+non-autonomous+control+of+apoptosis+in+development+and+disease.&rft.issn=1350-9047&rft.date=2016&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Eroglu+M&rft.au=Derry+WB&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CAnatomy%2C+Biochemistry%2C+Cell+Biology%2C+Developmental+Biology%2C+Reproduction%2C+Zoology">Eroglu M, & Derry WB (2016). Your neighbours matter - non-autonomous control of apoptosis in development and disease. <span style="font-style: italic;">Cell death and differentiation</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/27177021" rev="review">27177021</a></span>
<br />
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">For
more information or classroom activities on apoptosis and synthaesthesia, see:</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Apoptosis
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.woodrow.org/teachers/bi/1997/apotosis/">http://www.woodrow.org/teachers/bi/1997/apotosis/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.lessoncorner.com/Science/Biology/Cell_Biology/Apoptosis">http://www.lessoncorner.com/Science/Biology/Cell_Biology/Apoptosis</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC256977/">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC256977/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ehow.com/how-does_5172524_steps-apoptosis.html">http://www.ehow.com/how-does_5172524_steps-apoptosis.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Apoptosis.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Apoptosis.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=wREkXDiTkPs&feature=fvwrel">http://www.youtube.com/watch?v=wREkXDiTkPs&feature=fvwrel</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.cellsalive.com/apop.htm">http://www.cellsalive.com/apop.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.celldeath-apoptosis.org/">http://www.celldeath-apoptosis.org/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.promega.com/resources/product-guides-and-selectors/protocols-and-applications-guide/apoptosis/">http://www.promega.com/resources/product-guides-and-selectors/protocols-and-applications-guide/apoptosis/</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria";"><a href="http://www.roche-applied-science.com/PROD.../apoptosis_003_004.pdf"><span style="font-style: normal;">www.roche-applied-science.com/PROD.../</span><b style="mso-bidi-font-weight: normal;"><span style="font-style: normal;">apoptosis</span></b><span style="font-style: normal;">_003_004.pdf</span></a></span></cite></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://abstracts.aspb.org/pb1997/public/P64/0400.shtml">http://abstracts.aspb.org/pb1997/public/P64/0400.shtml</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria";"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CHYQFjAA&url=http%3A%2F%2Fjcmb.halic.edu.tr%2Fpdf%2F4-1%2FProgrammed.pdf&ei=9R7eT5ebCoim8gSK-pj3Cg&usg=AFQjCNEscW4eeiFGAzLuSE-mQAhR_xF3lw"><span style="font-style: normal;">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CHYQFjAA&url=http%3A%2F%2Fjcmb.halic.edu.tr%2Fpdf%2F4-1%2FProgrammed.pdf&ei=9R7eT5ebCoim8gSK-pj3Cg&usg=AFQjCNEscW4eeiFGAzLuSE-mQAhR_xF3lw</span></a></span></cite></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria";"><a href="http://www.plantsciences.ucdavis.edu/faculty/durzan/146.pdf"><span style="font-style: normal;">www.</span><b style="mso-bidi-font-weight: normal;"><span style="font-style: normal;">plants</span></b><span style="font-style: normal;">ciences.ucdavis.edu/faculty/durzan/146.pdf</span></a></span></cite></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Synaesthesia
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://faculty.washington.edu/chudler/syne.html">http://faculty.washington.edu/chudler/syne.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://web.mit.edu/synesthesia/www/">http://web.mit.edu/synesthesia/www/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://synesthete.org/">http://synesthete.org/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.mixsig.net/">http://www.mixsig.net/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://nookkin.com/content/synesthesia.php">http://nookkin.com/content/synesthesia.php</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.quibblo.com/quiz/1fOzV6O/Do-You-Have-Synesthesia">http://www.quibblo.com/quiz/1fOzV6O/Do-You-Have-Synesthesia</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://matthewjamestaylor.com/blog/synesthesia-associating-colours-to-letters">http://matthewjamestaylor.com/blog/synesthesia-associating-colours-to-letters</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.enotes.com/documents/synesthesia-worksheet-1139">http://www.enotes.com/documents/synesthesia-worksheet-1139</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.psychologyinaction.org/2011/01/28/synesthesia-when-ordinary-activities-trigger-extraordinary-sensations/">http://www.psychologyinaction.org/2011/01/28/synesthesia-when-ordinary-activities-trigger-extraordinary-sensations/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.awaytoteach.net/?q=node/5128&quicktabs_2529=0&quicktabs_2530=3">http://www.awaytoteach.net/?q=node/5128&quicktabs_2529=0&quicktabs_2530=3</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="https://sites.google.com/site/synesthesiaresearchteam/">https://sites.google.com/site/synesthesiaresearchteam/</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com153tag:blogger.com,1999:blog-8136765635696545893.post-19016656204185117692018-01-18T06:00:00.000-05:002018-01-18T06:00:01.585-05:00Biological Fusion EnergyBiology Concepts – mitochondrial dynamics
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1rIhARaqgWSAh1a-sxqHzhr1JSFUHnVOIxrMEmKfZrtbW-F-qYbD45P5mvPzP0xTpNb-XpsNxEXT4tmAboBUjCfaXJ4Vlbf2iSlRlEeXphe1ZAeWFx3omywXxjCFAvpouZ0Y5GGhkrp7D/s1600/1-nuclear+sunset.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1rIhARaqgWSAh1a-sxqHzhr1JSFUHnVOIxrMEmKfZrtbW-F-qYbD45P5mvPzP0xTpNb-XpsNxEXT4tmAboBUjCfaXJ4Vlbf2iSlRlEeXphe1ZAeWFx3omywXxjCFAvpouZ0Y5GGhkrp7D/s400/1-nuclear+sunset.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Stars
are the largest fusion reactors around,
and organisms do use </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">some of the energy our Sun
produces by joining two hydrogen atoms </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">into a
helium atom - remember photosynthesis? Fission reactors are </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">closer to home, but
are much less efficient -- and can melt down </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">and
kill us all. Cellular fission and
fusion are about joining
and </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">splitting things as well, just without the
release of energy. </span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
In the typical picture of a working cell, you would see millions of vacuoles traveling around, joining together and splitting off from organelles. The general proposition is that a bag of stuff <b>fuses</b>
(joins) or <b>fissions</b> (separates) from another bag of stuff.<br />
<br />
In physics, fission and fusion can be sources of great energy, but in cells they usually require an
input of energy. If the processes were the same, we could run the world’s
electronics on biology power – a true <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">cell phone</span>!</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Fusing and fissioning are easy for vacuoles, they have one
membrane. But the mitochondria and chloroplasts we have been looking at for the
past few posts have very specific, double membrane structures. The outer
membrane and inner membranes form a intermembrane space that is crucial for
their function, and the inner membranes have specific forms and structures that are necessary to make carbohydrate or ATP. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Wouldn’t fusing or splitting these organelles destroy the
membrane structures needed to maintain their functions? Indeed, the typical
cartoon of the cell shows individual mitochondria or chloroplasts floating
around in the cell, doing their jobs, but not interacting with the other
organelles or with each other.</div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgA4vdpbTrlu7dBdnYLMhEg7pyvIvhz1BjvMR7W9pwEPKev2xkbUMBiB15w2URCIEsumfPQTOSo6HLF0IFPJjlYdhSkbxQ4p2o-qFUHQBKtHA5DolMloeRh288F-YxCvzE8vmTzX6vBZn_E/s1600/2-fibroblast+tube+mito.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="231" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgA4vdpbTrlu7dBdnYLMhEg7pyvIvhz1BjvMR7W9pwEPKev2xkbUMBiB15w2URCIEsumfPQTOSo6HLF0IFPJjlYdhSkbxQ4p2o-qFUHQBKtHA5DolMloeRh288F-YxCvzE8vmTzX6vBZn_E/s320/2-fibroblast+tube+mito.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">The
structure pictured in green is, believe, it or not, the</span></div>
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<span style="font-family: "times"; font-size: 10pt;">mitochondrion
of a fibroblast (fibro = fiber and blast =</span></div>
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<span style="font-family: "times"; font-size: 10pt;">sprout)
cell, one that makes connective tissue. This doesn’t</span></div>
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<span style="font-family: "times"; font-size: 10pt;">look
much like the mitochondrion in the biology books,</span></div>
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<span style="font-family: "times"; font-size: 10pt;">does it?
The different strands join together and separate</span></div>
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<span style="font-family: "times"; font-size: 10pt;">constantly.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">For
mitochondria</span> at least, this picture is misleading. In many cells, the
mitochondria do not look like independent structures floating within the cell.
They look more like strands of spaghetti on your plate. Mitochondria can also
move around, they fuse together and break apart, they are recruited to
different subcellular areas based on energy need, and they can exchange
organellar content. <br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
All these features (shape, communication, movement,
fusion, fission, and exchange) are dynamic, meaning that they change with time
and are regulated. First recognized as a regulated process about 10 years ago,
this has spawned a new line of research called <b style="mso-bidi-font-weight: normal;">mitochondrial dynamics</b>.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Changes in morphology are also involved in progression
through the cell cycle. A 2009 study showed that in cultured cells, the
mitochondria must fuse together into branched networks in order for the cell to
enter the phase when it replicates its DNA. Now it appears that this changing
mitochondrial morphology is important for other shifts in cell fate. The same
group that conducted the 2009 study above showed in May 2012 that <a href="http://jcb.rupress.org/content/197/4/487.abstract">mitochondrial fusion and fission are important for oogenesis differentiation</a> (the changes an egg goes through to become different types of cells) in fruit fly egg chambers, implying their importance
in differentiation of other cells too.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
It appears that fusion and fission help to maintain the
correct number of mitochondria, but also work in the preservation of
mitochondrial function. Defective proteins can be kicked out if there are
normal proteins to replace them. Fusion of mitochondria can provide these
normal proteins. In other instances, low oxygen or low carbohydrate
concentrations can bring fission and fusion so that the mitochondria can share
nutrients and prevent their own degradation.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Most importantly, defective mitochondrial DNA (mtDNA) can be minimized by combining
or being replaced it with normal DNA from functioning mitochondria. In most cases,
recombination of DNA serves to increase genetic diversity, but with mtDNA it
seems the opposite effect is desired. Recombining and exchanging DNA serves to
maintain a single uniform genome for all the mitochondria; fusion can preserve
the integrity of the mitochondrial genome. Mutations or defects in either
exchange, fission, or fusion systems result in poor mitochondrial function and
identifiable diseases.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDBiGwXrFeGriAra3AKtBffpT869xLBBpKxA9TZWzqUbWLX_h6rXA-ZYRSvhGQfDeCmNsJ0CR9-pL6lWumY09Q75MJ_xUThPPVdzsDX6Q-q144VJaCJqkfI47YlKS1MBhedZENhcuAbq5s/s1600/3-eds-knee.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDBiGwXrFeGriAra3AKtBffpT869xLBBpKxA9TZWzqUbWLX_h6rXA-ZYRSvhGQfDeCmNsJ0CR9-pL6lWumY09Q75MJ_xUThPPVdzsDX6Q-q144VJaCJqkfI47YlKS1MBhedZENhcuAbq5s/s320/3-eds-knee.JPG" width="240" /></a></td></tr>
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<span style="font-family: "times"; font-size: 10pt;">People
with Charcot-Marie Tooth have very high </span></div>
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<span style="font-family: "times"; font-size: 10pt;">arches,
and are most often double jointed. Would </span></div>
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<span style="font-family: "times"; font-size: 10pt;">you
enjoy having your knees bend the other </span></div>
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<span style="font-family: "times"; font-size: 10pt;">direction?
I can tell you from personal experience, </span></div>
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<span style="font-family: "times"; font-size: 10pt;">that
double jointed people are very hard to wrestle </span></div>
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<span style="font-family: "times"; font-size: 10pt;">against.
They can slip out of whatever hold you try </span></div>
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<span style="font-family: "times"; font-size: 10pt;">on them.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">If the
fusion</span> of mitochondria is defective, a disease called <b style="mso-bidi-font-weight: normal;">Charcot-Marie-Tooth</b> type 2a may
result. This is a neuronal
degenerative disease that usually affects the lower extremities more than the
arms. Most cases are caused by defects in the cells that surround the neural
<b>axon</b> (the long projection between the cell body and the connection point to other
neurons), but in type 2a, the defect is in the axon, specifically the inability
of mitochondria to fuse. Therefore, fusion must be important.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In <b style="mso-bidi-font-weight: normal;">Huntington’s
disease</b>, there is too much mitochondrial fission. Huntington’s chorea
(chorea = dance, patients with this disease develop large uncontrollable
movements that make it look like they are dancing). The cause is an expansion
in the <b style="mso-bidi-font-weight: normal;">huntingtin gene</b> (yes, I
spelled it right); a three DNA base repeat (CAG) is mutated and becomes
repeated too many times. This affects the function of the huntingtin protein.
The age of onset and speed of progression are related to how expanded the
triplet repeat is. As of today, this <b style="mso-bidi-font-weight: normal;">autosomal
dominant genetic disease</b> (only need to inherit one mutant gene for it to
occur) is untreatable and fatal.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
However, the mechanism by which this mutation causes neuron
degeneration is just becoming clear.
A 2010 study indicated that the mutant huntingtin protein interacts with
the proteins that control mitochondrial fission and makes them overactive. Too
much fission disrupts mitochondrial functions and the neurons become defective
and then die. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Even more important, in terms of numbers of people affected,
is the link between reduced mitochondrial fission and Alzheimer’s disease.
Scientists know that it was the build up of amyloid protein that promotes
neuron degeneration, but until recently, they didn’t know how it was occurring.
It turns out that the plaque proteins can stimulate nitric oxide production,
which then damages the fission proteins of the mitochondria. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgx-ZvrWzI6i9LDq0bbvV8J7hbfJnsK99YPabqyP8QjGPDOzKI3Hz3a-a_3rebUtRb_TeGeklqVNpAL5rxJCFzrCPQeI_BDY4s3tO5LTphclbkT5LB39XzSg9EPaktIdHmJ2nwTgxGBMQiB/s1600/4-fission.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="224" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgx-ZvrWzI6i9LDq0bbvV8J7hbfJnsK99YPabqyP8QjGPDOzKI3Hz3a-a_3rebUtRb_TeGeklqVNpAL5rxJCFzrCPQeI_BDY4s3tO5LTphclbkT5LB39XzSg9EPaktIdHmJ2nwTgxGBMQiB/s320/4-fission.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">DRP1
proteins are important for the fission of a </span></div>
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<span style="font-family: "times"; font-size: 10pt;">mitochondrion
into two mitochondria. They oligomerize </span></div>
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<span style="font-family: "times"; font-size: 10pt;">(join
together in groups) and pinch the mitochondria </span></div>
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<span style="font-family: "times"; font-size: 10pt;">apart.
Nitric oxide can damage the DRP1 proteins – so </span></div>
<span style="font-family: "times"; font-size: 10pt;">no mitochondrial
fission.</span>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">This is
huge</span> news because preventing this nitric oxide damage might be a way to
slow or stop Alzheimer’s progression. This is a difficult area of research,
since nitric oxide is important in many biochemical pathways; just shutting
down nitric oxide production everywhere in the body would lead to defective
hair growth, blood vessel pressure control, abnormal blood clotting and
atherosclerosis, ……oh, and Viagra wouldn’t work either.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The movement of mitochondria within cells is also crucial
for their function. The longest cells in your body are your motor neurons. A
single cell can be several feet long. Your mitochondria must get to where
they are needed along the axon of the
neuron, and this requires regulated transport and communication. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Defective transport is one outcome during
Charcot-Marie-Tooth type 2a defective mitochondrial fusion and in
overstimulation of mitochondrial fission in Huntington’s disease. In addition,
defective axonal transport of mitochondria may turn out to be an important
early defect in Alzheimer’s disease. In fact, defective transport of
mitochondria may play a role in Parkinson’s disease, amyotrophic lateral
sclerosis (Lou Gehrig’s disease) and other neurodegenerative diseases that
involve defective mitochondrial fusion and fission. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Why might this be….. I’m not sure, but here is a guess. Defective
fusion or fission leads to defective function – defective function leads to
reduced ATP formation – reduced ATP results in defective energy-requiring
functions of the cell, like transport of mitochondria from one place to
another. I have no evidence for this, but it is a logical, testable hypothesis.
It could be that defective transport is an effect, not a cause, of these
diseases -at least in part.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgswHrvInxl4rBb4DeeZ6bcJ12Bl6e3c_vWotX8-WGvaN4p3BpIKZnJfIL-gVI8rX1U7xrKe2xZZ3DUYOHYQGqz9mcqSUo3ducmb2VE-76FNdcbeClVbtDCefDeNGOENZ3tNR-L4db7w1_o/s1600/5-+parkinsons.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgswHrvInxl4rBb4DeeZ6bcJ12Bl6e3c_vWotX8-WGvaN4p3BpIKZnJfIL-gVI8rX1U7xrKe2xZZ3DUYOHYQGqz9mcqSUo3ducmb2VE-76FNdcbeClVbtDCefDeNGOENZ3tNR-L4db7w1_o/s320/5-+parkinsons.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">Two of
our more famous Parkinson’s patients; </span></div>
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<span style="font-family: "times"; font-size: 10pt;">Muhammed
Ali and Michael J. Fox. Float like Marty</span><br />
<span style="font-family: "times"; font-size: 10pt;">McFly and sting like a bee?</span></div>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">For
Parkinson’s</span> disease, a 2009 study showed that defective mitochondrial
transport occurred due to dysfunction in the fusion/fission system, independent
of changes in the ATP level. However, ATP production is not the only function
of mitochondria. They also work in regulating the amount of calcium in the
cell, and altered calcium levels can lead to disruption of the cytoskeletal
transport mechanisms. Maybe I need to tweek my hypothesis; it is
fusion/fission-mediated defects in several mitochondrial functions that
then cause axonal transport changes that are noted in many neurodegenerative
disorders. Now design an experiment to test it - this is how scientists go
about their work.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So we see that the mitochondria are not static, they are
changing all the time and that these changes are crucial for their function and
integrity. Here is our exception in the similarities of chloroplasts and
mitochondria. It would seem, at least based on current evidence, chloroplasts
are relative loners.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This is not to say that can’t be dynamic. We have seen that
<a href="http://biologicalexceptions.blogspot.com/2012/06/seeds-of-inheritance.html">chloroplasts have a definitive inheritance pattern</a>, either maternal or
paternal, and they will fight to maintain this pattern. Chloroplast fusion has
been most often described in the <b style="mso-bidi-font-weight: normal;">zygote</b>
(initial cell formed by fusion of the gametes during fertilization, from Greek
zygota = joined or yoked together) of algae. In these cases, which are still
rare, the chloroplast genome of one of the two fused organelles will be
degraded. Fusion of other chloroplasts, as in mature plant cells, either does not
occur or has not been studied, because I can’t find any publications describing
it. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm1GWx0ww7beI4s1wT-Y87pCeq_IlLksZNftOcKOuWikQosbSMluCIjM79zbSi8Fwlbx-OVbIepl6DC2OElgvm1pAaYrxUQSgcdOH9gRzb9JWPmXJCx7TwsyTL2oM9C6CnGEMh1MM4XLwu/s1600/6-chloroplast+projection.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="166" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjm1GWx0ww7beI4s1wT-Y87pCeq_IlLksZNftOcKOuWikQosbSMluCIjM79zbSi8Fwlbx-OVbIepl6DC2OElgvm1pAaYrxUQSgcdOH9gRzb9JWPmXJCx7TwsyTL2oM9C6CnGEMh1MM4XLwu/s400/6-chloroplast+projection.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">These
are examples of the dynamic activities of chloroplasts. </span></div>
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<b style="mso-bidi-font-weight: normal;"><span style="font-family: "times"; font-size: 10pt;">Stromule</span></b><span style="font-family: "times"; font-size: 11pt;">
connections can be formed between chloroplasts for </span></div>
<div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">the
passage of organelle contents. They are usually 0.5 microns </span></div>
<div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">in
diameter (1/500,000 of a meter) and can be found in all types </span></div>
<div class="MsoNormal" style="mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">
<span style="font-family: "times"; font-size: 10pt;">of
plastids. Their function – not completely known yet.</span></div>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">On the</span>
other hand, chloroplasts aren’t complete loners either. As far back as the
1960’s there were reports saying that chloroplasts might have certain
connections at certain times. More recent studies indicate that small
connections can be formed between chloroplasts, often called tubular
connections or <b style="mso-bidi-font-weight: normal;">stromules</b>. It is
interesting that stromules can be formed between chloroplasts and mitochondria.
It is believed that this is one way the plant cell keeps these two organelles
close to one another, since their functions, products, and by-products are so
interrelated.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
You might ask why the mitochondria and chloroplasts that have so
much in common differ in their relative dynamic properties. They were both
once free organisms that had to have lots of interactions with other members of
their species, but only the mitochondria seemed to have preserved it. Next week, we will look into how this
mitochondrial dynamism is even more crucial organism survival – by regulating
cell death. Believe it or not, cells have to know how to die well.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=J+Cell+Biol&rft_id=info%3Adoi%2F10.1083%2Fjcb.201110058&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=DRP1-dependent+mitochondrial+fission+initiates+follicle+cell+differentiation+during+Drosophila+oogenesis+&rft.issn=&rft.date=2012&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Kasturi+Mitra%2C+Richa+Rikhy%2C+Mary+Lilly%2C+and+Jennifer+Lippincott-Schwartz&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Molecular+Biology%2C+Developmental+Biology">Kasturi Mitra, Richa Rikhy, Mary Lilly, and Jennifer Lippincott-Schwartz (2012). DRP1-dependent mitochondrial fission initiates follicle cell differentiation during Drosophila oogenesis <span style="font-style: italic;">J Cell Biol</span> DOI: <a href="http://dx.doi.org/10.1083/jcb.201110058" rev="review">10.1083/jcb.201110058</a></span>
</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">For
more information or classroom activities on mitochondrial dynamics or cellular
differentiation, see:</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Mitochondrial
dynamics – </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://mitodyn2011.azuleon.org/">http://mitodyn2011.azuleon.org/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.its.caltech.edu/~chanlab/main%20pages/research.html">http://www.its.caltech.edu/~chanlab/main%20pages/research.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=0NmBaw3grr4">http://www.youtube.com/watch?v=0NmBaw3grr4</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.plantmitochondria.net/Plant_Mitochondria/Movies.html">http://www.plantmitochondria.net/Plant_Mitochondria/Movies.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.nature.com/scitable/topicpage/mitochondrial-fusion-and-division-14264007">http://www.nature.com/scitable/topicpage/mitochondrial-fusion-and-division-14264007</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://biology.about.com/b/2010/04/23/mitochondrial-fusion.htm">http://biology.about.com/b/2010/04/23/mitochondrial-fusion.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.sciencedaily.com/releases/2010/04/100415125942.htm">http://www.sciencedaily.com/releases/2010/04/100415125942.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.sciencedaily.com/releases/2011/01/110124162712.htm">http://www.sciencedaily.com/releases/2011/01/110124162712.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ellisonfoundation.org/content/does-mitochondrial-fusion-protect-against-mitochondrial-dna-mutations-during-aging">http://www.ellisonfoundation.org/content/does-mitochondrial-fusion-protect-against-mitochondrial-dna-mutations-during-aging</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.its.caltech.edu/~chanlab/PDFs/Griffin_et_al_BBA_2006.pdf"><span style="font-style: normal;">www.its.caltech.edu/~chanlab/PDFs/Griffin_et_al_BBA_2006.pdf</span></a></span></cite></div>
<span style="font-family: "cambria"; font-size: 11pt;"><a href="https://research.uiowa.edu/arra/project/176">https://research.uiowa.edu/arra/project/176</a></span>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com130tag:blogger.com,1999:blog-8136765635696545893.post-27643773673896445702018-01-11T06:00:00.000-05:002018-01-11T06:00:04.506-05:00The Seeds of Inheritance<span style="font-family: "cambria"; font-size: 12pt;">Biology
Concepts – pollen, plastid inheritance, gymnosperms, angiosperms</span>
<br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">I am coming
to believe that plants are more complex than animals, even more complex than
females. Female plants must be the most difficult things on Earth to understand!</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrPCZ9Jruo7fX_O5FnGDgsp_qOcZDzHh_tbC6PCdMyY7LIJ40yI2F5U1R4E1KRuX5bY8vxDmNaqZo8c6dAdkxLTqn13b6C_3f7YYfxXWAC3mFSMhm9c9MP58Bhu6EnUeFADpcV6ryvttdI/s1600/1-mono+di.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="215" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrPCZ9Jruo7fX_O5FnGDgsp_qOcZDzHh_tbC6PCdMyY7LIJ40yI2F5U1R4E1KRuX5bY8vxDmNaqZo8c6dAdkxLTqn13b6C_3f7YYfxXWAC3mFSMhm9c9MP58Bhu6EnUeFADpcV6ryvttdI/s400/1-mono+di.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Complete
flowers have both anthers for pollen and
pistils for egg </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">fertilization. Incomplete flowers occur
on dioecious plants, </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">and have either the pistil
(gynoecious) or the anther </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">(androecious). Dioecious
plants cannot self pollinate, unless </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">they have
both types of incomplete flowers, like coast </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">redwoods
(see last picture).</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;">Yes, there</span><span style="font-family: "cambria"; font-size: 12pt;">
are female plants. In the plant world, species can be <b style="mso-bidi-font-weight: normal;">monoecious</b> (mono = one, and ecious = household) or <b style="mso-bidi-font-weight: normal;">dioecious</b> (di = two). Monoecious plants
have individuals that produce both male microgametophytes (pollen) and female
megagametophytes (oocyctes or ovules). The individual dioecious plants are
either <b style="mso-bidi-font-weight: normal;">androecious</b> (pollen
producing) or <b style="mso-bidi-font-weight: normal;">gynoecious</b> (seed
producing). It's okay to ask if a plant is female, but you still shouldn’t
ask her age.</span><br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">This isn’t
even the tip of the tip of the iceberg when it comes to diversity in plant
reproduction. There are also different ways to produce seeds. The <b style="mso-bidi-font-weight: normal;">gymnosperms</b> have unenclosed seeds
(gymno = naked, and sperm = seed). Gymnosperms include the <b style="mso-bidi-font-weight: normal;">conifers</b> (cone producers), the <a href="http://biologicalexceptions.blogspot.com/2012/05/its-plant-world-were-just-living-in-it.html">cycads that we talked a little about a few weeks ago</a>, and the gnetum plants. Gnetum plants live close to the equator
around the globe and include the <i style="mso-bidi-font-style: normal;">Ephedra</i>
species. It is from these plants that we get ephedrine and pseudoephedrine that
work to relieve allergy and cold congestion.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">The other
type of seed plants is the <b style="mso-bidi-font-weight: normal;">angiosperms</b>
(angio = hidden). These are the flowering plants that have seeds encased in
fruits or other structures that help to protect them and to encourage their
dispersal. </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">One way that
the gymnosperms and angiosperms differ is in how they inherit their
plastid organelles. But even here there is a lot of overlap and exceptions;
plants just keep getting more complex.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinBbGoA2NeA4cz_i2USWTaa2Z0LEWFyG9qZ59naP3AQgxuRcODoFGQXF2LlnAdlwZpu88uPUYEJe5uJrw1n5IER1TMk3AFyRn13urcbaPfWK5ZzXlJNnn0ZYHV9THu8MDCr1GnXcX3E9kx/s1600/2-angio+gymno.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinBbGoA2NeA4cz_i2USWTaa2Z0LEWFyG9qZ59naP3AQgxuRcODoFGQXF2LlnAdlwZpu88uPUYEJe5uJrw1n5IER1TMk3AFyRn13urcbaPfWK5ZzXlJNnn0ZYHV9THu8MDCr1GnXcX3E9kx/s400/2-angio+gymno.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Gymnosperms
have there seeds exposed on the scales </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">of
the cones, while angiosperms have the protected </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">inside
the fruit (except for strawberries).</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;">Angiosperms</span><span style="font-family: "cambria"; font-size: 12pt;"> have a maternal inheritance of chloroplast DNA (cpDNA), much like
animals have maternal inheritance of mitochondrial DNA (mtDNA). The reasons for
maternal inheritance of cpDNA elude me. For mitochondria, the theory is that
damage to the sperm mitochondria would occur during the swim to the oocyte, so it
would be smart to ban them from the egg. </span><br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">But cpDNA is
much more passive, they do not have to do a huge amount of work to get to the
ovule of the pollinated plant. The pollen tube grows down to the ovule and
delivers the sperm cells right to the egg. There must be some other reason, but
I don’t know what it might be.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">However,
there seem to be more exceptions in angiosperm inheritance of cpDNA than there is in animal mtDNA. A few families of plants, like alfalfa (<i style="mso-bidi-font-style: normal;">Medicago sativa</i>) and kiwi fruit vine (<i style="mso-bidi-font-style: normal;">Actinidia deliciosa</i>), have a strict
paternal inheritance of cpDNA. This is odd since, the angiosperms have a couple of
mechanisms for keeping the plastids out of the male gametes.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgk90whXlXvu2NqusL3bHEPsD_ACZtWAyWLOA0DkIiW4HNoySITNkzffFbkMIzULkC37OtTTt6IMYmM1QotGuLDiOrS3wO0hruMWbcilFZwn6eQ6wT5SuHU9_T3BLIw6zNW3TbzKpWXWViX/s1600/3-+pollen+grains.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgk90whXlXvu2NqusL3bHEPsD_ACZtWAyWLOA0DkIiW4HNoySITNkzffFbkMIzULkC37OtTTt6IMYmM1QotGuLDiOrS3wO0hruMWbcilFZwn6eQ6wT5SuHU9_T3BLIw6zNW3TbzKpWXWViX/s1600/3-+pollen+grains.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Every
plant species has a distinct pollen shape, which </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">is
why you can be allergic to some plants and not </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">others.
But each pollen grain has the vegetative cell </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">that
becomes the sperms cells and the tube cell. The </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">tube
usually grows from the side that rests on the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">fertilized
stigma.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;">The pollen</span><span style="font-family: "cambria"; font-size: 12pt;">
grain contains a few different kinds of cells. There are one or more generative
cells; these are the reproductive cells of the pollen. There will also be many
non-vegetative cells as well. The generative cell has two nuclei. One will
divide to become the two sperm cells, while the other will form the tube cell
to deliver the sperms cells to the
ovule. </span><br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">In many
species, when the generative nucleus divides to form sperm, the plastids are
partitioned off, and are not included in the sperm cells. This works to ensure
maternal inheritance. In other species, the sperm cells may include plastids,
but these quickly degenerate and are not delivered to the ovule. Somehow, the
alfalfa plants have overcome these mechanisms and even invented a new one to
eliminate or exclude the plastids from the ovule, giving strict paternal
inheritance.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">Going beyond
the alfalfa and kiwi fruit ability to preserve their paternal plastids is the
fact that a full 20% of angiosperms can show (but don’t have to show),
bipaternal inheritance of cpDNA. This is called <b style="mso-bidi-font-weight: normal;">potential bipaternal plastid inheritance</b> (PBPI) and is controlled by a male
gametic trait, called of all things - PBPI trait! Therefore, the fairly strict
maternal inheritance of mtDNA in animals (<a href="http://biologicalexceptions.blogspot.com/2012/05/every-day-should-be-mothers-day.html">blue mussels excepted</a>) is not matched
by cpDNA in angiosperms. </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">But it gets
weirder. The angiosperm exception is normal for the gymnosperm. Gymnosperms
tend to have paternal inheritance patterns for cpDNA. This difference is
important to note, since scientists often try to use cpDNA inheritance patterns
to track seed movements around the world and through evolutionary time, just
like human populations are often tracked using mitochondrial ancestry and
inheritance.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">But this
must be frustrating, because there are also exceptions in the paternal
inheritance pattern in gymosperms. The Chinese fir (<span class="st"><i style="mso-bidi-font-style: normal;">Cunninghamia lanceolata</i>)</span>, which
isn’t a fir, is native to Asia but was brought to America in the 1800’s.
Remember that before molecular biology, most taxonomic classifications were made
on just the morphology (shape and look) of an organism, and its grouping and
name were based on how it compared to other organisms. Names often get stuck in
the language and are hard to change, so many of the misnomers persist. </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7gpa-F559sUkniHhEl8SOKrbishAPAg2wMJv45MwjCkrUehQvv6mlIOmcVaihBxhB0ZDP9Plh4uO2PWK5FAawLVoE3nbCltXz94ROu0axBs5ppf574nIVIxKEQohoNMCX1hSEFkI0RftR/s1600/4-gojira.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="215" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7gpa-F559sUkniHhEl8SOKrbishAPAg2wMJv45MwjCkrUehQvv6mlIOmcVaihBxhB0ZDP9Plh4uO2PWK5FAawLVoE3nbCltXz94ROu0axBs5ppf574nIVIxKEQohoNMCX1hSEFkI0RftR/s320/4-gojira.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Godzilla,
or Gojira, always seemed surprised when </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">the
other monster grabbed his tail. Here it happens </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">to
be a giant wolfman. Everybody cashed in on the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">werewolf
brand; I am surprised Abbott and Costello </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">aren’t
in that picture somewhere.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;">Consider </span><span style="font-family: "cambria"; font-size: 12pt;">this,
we now know that the Japanese pronunciation for the big green movie monster is
“go-zeer-a” or “go-jeer-a,” as it was a portmanteau of the Japanese words for
gorilla and whale. But when it came to America, it was just assumed that the
name was mispronounced in English and that it was supposed to be “god-zill-a.”
We know it is wrong, but the wrong name still survives; it's what you get used
to that sticks around.</span><br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">But back to
the Chinese fir. This gymnosperm is a conifer that can grown 150 feet tall, but
flaunts its individuality by having a maternal inheritance pattern for cpDNA – much more
angiosperm-like behavior than gymnosperm. And this is even odder because the Chinese
fir is an older gymnosperm, a much more distant relative to the angiosperms
than many gymnosperms that have a strict paternal cpDNA inheritance.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">Gymnosperms
that show maternal cpDNA inheritance are rare, or just less studied, so one
might assume that paternal cpDNA inheritance is fairly strict – wrong. Many
gymnosperms have bipaternal inheritance patterns of plastids, so the mechanism
might be different from angiosperms, but is no more consistent than that of the
flowering plants.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">Finally,
there is the issue of crossbreeding. In this animal mtDNA and plant cpDNA seem
to be similar. Whatever the dominant form of inheritance is seen in natural
breedings, the numbers get screwed up when cross breeding occurs. We saw that
<a href="http://biologicalexceptions.blogspot.com/2012/05/every-day-should-be-mothers-day.html">paternal inheritance of mtDNA in mice</a> was much likely in the mating of
different species (<b>interspecific breeding</b>).</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMuecS1IMDC6U4L2TbNE51ThMMllqIjgsI3LVKaMxxHdaRgFahsiFa5i8nQ7lQubl-mJT56RqJLsV5xSITYaPZ8BsMNYY10XAfkiO8SCo9pn9rTP90RV5xRFOtP2Sk-JC9Auvih9XHmCg9/s1600/5-passion+fruit.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMuecS1IMDC6U4L2TbNE51ThMMllqIjgsI3LVKaMxxHdaRgFahsiFa5i8nQ7lQubl-mJT56RqJLsV5xSITYaPZ8BsMNYY10XAfkiO8SCo9pn9rTP90RV5xRFOtP2Sk-JC9Auvih9XHmCg9/s320/5-passion+fruit.jpg" width="315" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">The
passionflower vine can grow to be 10 meters high </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">and
is the source of the passion fruit that I enjoy so </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">much.
The fruit protects the fertilized seeds<span style="font-family: "cambria";"> </span>that </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">probably
have paternal cpDNA, since most of the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">varieties
we eat are hybrids of different species.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;">In plants</span><span style="font-family: "cambria"; font-size: 12pt;">,
this also holds, and may even be more discrepant. Take the passion flowers (family <i style="mso-bidi-font-style: normal;">Passiflora</i>) for instance. <b>Intraspecific breeding</b> (same species)
showed the maternal cpDNA inheritance one might expect. But in interspecific
crosses the inheritance was 100% paternal. This must represent some attempt to
limit the genetic diversity of the organellar genomes, but I leave it to you to
explain the reason for it.</span><br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">The
similarity between mitochondrial and plastid inheritance in hybrids
brings up another issue – what about mitochondrial inheritance patterns in
plants?</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">It turns out
that most plants that have been studied for mtDNA inheritance have a maternal
inheritance pattern, just like animals. Amazingly, this includes the gymnosperms,
most of which have paternal inheritance of cpDNA. But even some plants with
maternal cpDNA patterns can pass on paternal mitochondria. An example of this
is the banana - tomorrow morning you can feel like a rebel for garnishing your
cornflakes with such an outlaw fruit.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">However, the
reason would be different. Remember that sperm have their mitochondria in their
tails, and in most animals, this is not included in what enters the egg or is
degraded just after entering. But <a href="http://biologicalexceptions.blogspot.com/2012/05/its-plant-world-were-just-living-in-it.html">few plants have flagellar sperm</a> (like the cycads
we talked about before). The sperm mtDNA is not exposed to anymore oxygen
radical damage than the ovule mtDNA, yet there is most often uniparental,
maternal inheritance.</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8wSGEtY5Sk9Yqs2Jj0824ZD7GBpWr-0JoWHmp1-DCx2hv2750wHWA-ehqfB2WSkayS8tSiO4BTmZHnDnreZJGvwyQNDgR42C2NoAPo5VUp-qEQMld8UjCbOmaohX1p-iCT_A2TxHA3GQF/s1600/6-redwood.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8wSGEtY5Sk9Yqs2Jj0824ZD7GBpWr-0JoWHmp1-DCx2hv2750wHWA-ehqfB2WSkayS8tSiO4BTmZHnDnreZJGvwyQNDgR42C2NoAPo5VUp-qEQMld8UjCbOmaohX1p-iCT_A2TxHA3GQF/s320/6-redwood.JPG" width="226" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Coastal
redwoods can reach up to 110 meters </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">(360
ft) tall, but their roots may only go 6 ft. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">underground.
What's holding this tree in place? </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">It
has two different types of leaves, and has male </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">and
female branches and flowers, but all its </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">mitochondria
and chloroplasts come from one </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">place,
its father.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;">The interesting</span><span style="font-family: "cambria"; font-size: 12pt;"> cases are those like the gymnosperms; paternal cpDNA, but
maternal mtDNA. Once again, the plants are much more complex and intricate in
their behaviors than animals, as two separate mechanisms for organellar retention
and degradation must be at work in these plants. But even here there can be exceptions. The coast
redwood (<i style="mso-bidi-font-style: normal;">Sequoia sempervirens</i>) has
normal gymnosperm (paternal) inheritance of cpDNA, but it also has paternal
inheritance of mtDNA! And the Chinese fir, which breaks the rules and is a
gymnosperm with maternal inheritance of cpDNA, also makes itself exceptional in
that it has paternal inheritance of mtDNA! Very confusing.</span><br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 12pt;">So
mitochondria and chloroplasts both work in energy production, both evolved
through endosymbiosis, both have single, circular chromosomes (with
exceptions), and both have uniparental inheritance patterns (with exceptions).
Next week, let’s look a behavior that is different in these two organelles.</span><br />
<br />
<br />
<br />
<br /></div>
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+plant+research&rft_id=info%3Apmid%2F20052516&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Why+does+biparental+plastid+inheritance+revive+in+angiosperms%3F&rft.issn=0918-9440&rft.date=2010&rft.volume=123&rft.issue=2&rft.spage=201&rft.epage=6&rft.artnum=&rft.au=Zhang+Q&rft.au=Sodmergen&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CBotany%2C+Cell+Biology%2C+Reproduction%2C+Genetics+%2C+Evolutionary+Biology%2C+Molecular+Biology%2C+Developmental+Biology">Zhang Q, & Sodmergen (2010). Why does biparental plastid inheritance revive in angiosperms? <span style="font-style: italic;">Journal of plant research, 123</span> (2), 201-6 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/20052516" rev="review">20052516</a></span><br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Chromosome+research+%3A+an+international+journal+on+the+molecular%2C+supramolecular+and+evolutionary+aspects+of+chromosome+biology&rft_id=info%3Apmid%2F23681660&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=DNA+abandonment+and+the+mechanisms+of+uniparental+inheritance+of+mitochondria+and+chloroplasts.&rft.issn=0967-3849&rft.date=2013&rft.volume=21&rft.issue=3&rft.spage=287&rft.epage=96&rft.artnum=&rft.au=Bendich+AJ&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Botany%2C+Biochemistry%2C+Genetics+%2C+Reproduction%2C+Molecular+Biology"><br /></span>
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Chromosome+research+%3A+an+international+journal+on+the+molecular%2C+supramolecular+and+evolutionary+aspects+of+chromosome+biology&rft_id=info%3Apmid%2F23681660&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=DNA+abandonment+and+the+mechanisms+of+uniparental+inheritance+of+mitochondria+and+chloroplasts.&rft.issn=0967-3849&rft.date=2013&rft.volume=21&rft.issue=3&rft.spage=287&rft.epage=96&rft.artnum=&rft.au=Bendich+AJ&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Botany%2C+Biochemistry%2C+Genetics+%2C+Reproduction%2C+Molecular+Biology">Bendich AJ (2013). DNA abandonment and the mechanisms of uniparental inheritance of mitochondria and chloroplasts. <span style="font-style: italic;">Chromosome research : an international journal on the molecular, supramolecular and evolutionary aspects of chromosome biology, 21</span> (3), 287-96 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/23681660" rev="review">23681660</a></span>
<br />
<br />
<br />
<br />
<div class="MsoNormal">
<span style="font-size: 10pt;">For
more information or classroom activities on monoecious/dioecious plants,
angiosperms, gymnosperms, or plastid inheritance, see:</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Monoecious/dioecious
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.saylorplants.com/SaylorPlants/Ref_Info/Dioecious2w.htm">http://www.saylorplants.com/SaylorPlants/Ref_Info/Dioecious2w.htm</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEkQFjAA&url=http%3A%2F%2Foklahoma4h.okstate.edu%2Flitol%2Ffile%2Fothers%2Fenrichment%2F4h500.pdf&ei=aXvKT4TuMIeC2wW1q4HaCw&usg=AFQjCNGyz1D_o5uVX0nMrNa2VpjchuJHgw">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CEkQFjAA&url=http%3A%2F%2Foklahoma4h.okstate.edu%2Flitol%2Ffile%2Fothers%2Fenrichment%2F4h500.pdf&ei=aXvKT4TuMIeC2wW1q4HaCw&usg=AFQjCNGyz1D_o5uVX0nMrNa2VpjchuJHgw</a></span></cite></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"><a href="http://botany.csdl.tamu.edu/FLORA/Wilson/pp/s99/flowers.htm">http://botany.csdl.tamu.edu/FLORA/Wilson/pp/s99/flowers.htm</a></span></cite></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.oakleafgardening.com/glossary-terms/hermaphrodite-monoecious-dioecious/">http://www.oakleafgardening.com/glossary-terms/hermaphrodite-monoecious-dioecious/</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"><a href="http://www.bushmansfriend.co.nz/dioecious-plants-xidc18308.html">http://www.bushmansfriend.co.nz/dioecious-plants-xidc18308.html</a></span></cite></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Angiosperms
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ehow.com/info_8462298_classroom-activities-angiosperms.html">http://www.ehow.com/info_8462298_classroom-activities-angiosperms.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CHIQFjAI&url=http%3A%2F%2Fwww.burpeehomegardens.com%2Fpdf%2FBHC10538-BurpeeICanGrow-PlantClassification.pdf&ei=vn3KT5-dNMnW2gXOjc3ZCw&usg=AFQjCNH5IaI0aDUM1qd4wj_tVEaF-o8-jw">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CHIQFjAI&url=http%3A%2F%2Fwww.burpeehomegardens.com%2Fpdf%2FBHC10538-BurpeeICanGrow-PlantClassification.pdf&ei=vn3KT5-dNMnW2gXOjc3ZCw&usg=AFQjCNH5IaI0aDUM1qd4wj_tVEaF-o8-jw</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://alex.state.al.us/lesson_view.php?id=24127">http://alex.state.al.us/lesson_view.php?id=24127</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.teachervision.fen.com/seeds/printable/28684.html">http://www.teachervision.fen.com/seeds/printable/28684.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://beckyboop.wordpress.com/2011/04/05/flowering-plants-lesson-plan/">http://beckyboop.wordpress.com/2011/04/05/flowering-plants-lesson-plan/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="https://www.google.com/#hl=en&sclient=psy-ab&q=gymnosperms+and+angiosperms&oq=gymnosperm&aq=1&aqi=g4&aql=&gs_l=serp.1.1.0l4.50243.54373.3.55834.20.16.1.1.1.13.328.3452.0j9j6j1.16.0...0.0.2xyYaWj6zCc&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=9d6464494833e">https://www.google.com/#hl=en&sclient=psy-ab&q=gymnosperms+and+angiosperms&oq=gymnosperm&aq=1&aqi=g4&aql=&gs_l=serp.1.1.0l4.50243.54373.3.55834.20.16.1.1.1.13.328.3452.0j9j6j1.16.0...0.0.2xyYaWj6zCc&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=9d6464494833eb73&biw=1689&bih=895</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Gymnosperms
– </span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.clt.astate.edu/mhuss/Lab%20Exercise%2011.doc"><span style="font-style: normal;">www.clt.astate.edu/mhuss/Lab%20Exercise%2011.doc</span></a></span></cite><i style="mso-bidi-font-style: normal;"><span style="font-size: 11pt;"></span></i></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://faculty.unlv.edu/landau/gymnosperms.htm">http://faculty.unlv.edu/landau/gymnosperms.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.gardenbuildingsdirect.co.uk/Article/gymnosperms">http://www.gardenbuildingsdirect.co.uk/Article/gymnosperms</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://alex.state.al.us/lesson_view.php?id=24115">http://alex.state.al.us/lesson_view.php?id=24115</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://sfr.psu.edu/youth/sftrc/lesson-plans/forestry/6-8/gymnosperms">http://sfr.psu.edu/youth/sftrc/lesson-plans/forestry/6-8/gymnosperms</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://academic.kellogg.edu/herbrandsonc/bio111/gymnosperms.htm">http://academic.kellogg.edu/herbrandsonc/bio111/gymnosperms.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/seed%20plants/seed%20plants.htm">http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/seed%20plants/seed%20plants.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.msnucleus.org/membership/html/k-6/lc/plants/5/lcp5_5a.html">http://www.msnucleus.org/membership/html/k-6/lc/plants/5/lcp5_5a.html</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Plastid
inheritance - </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/20052516">http://www.ncbi.nlm.nih.gov/pubmed/20052516</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.amjbot.org/content/94/1/42.full">http://www.amjbot.org/content/94/1/42.full</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.generationcp.org/plantbreeding/index.php?id=015">http://www.generationcp.org/plantbreeding/index.php?id=015</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.clivias.com/Articles/Article016.htm">http://www.clivias.com/Articles/Article016.htm</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com53tag:blogger.com,1999:blog-8136765635696545893.post-74442399845100199752018-01-04T06:00:00.000-05:002018-01-04T06:00:00.327-05:00Every Day Should Be Mother’s DayBiology concepts – inheritance patterns, mitochondria, fertilization,
lineage, mitochondrial Eve<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
What do the “The Battle Hymn of the Republic”, Mother’s Day, and all your mitochondria all have in common? </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjALhmFijMe8ArJ8pr1M40HMptUgiVycH66NTybb0MVbCYXjYYMooK6GHlXouBPR8lG2qnUkQTZCfAI-JEooTyetcJfDQUyVn2Tlu-kwXESgCqLBel31QfBtlDja_z2LuZ0ibg3VN1dUJGZ/s1600/1-howe.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjALhmFijMe8ArJ8pr1M40HMptUgiVycH66NTybb0MVbCYXjYYMooK6GHlXouBPR8lG2qnUkQTZCfAI-JEooTyetcJfDQUyVn2Tlu-kwXESgCqLBel31QfBtlDja_z2LuZ0ibg3VN1dUJGZ/s320/1-howe.jpg" width="266" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Julia Ward
Howe wrote the words for The </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Battle Hymn
of the Republic after meeting </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Abraham
Lincoln. She wrote it as a poem, </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">but also as
new lyrics for the existing song </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">called, John
Brown’s Body. I wonder if she </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">had
copyright issues to deal with.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The first</span>
two are easy; Julia Ward Howe wrote the Battle Hymn of the Republic as a Union
anthem during the Civil War, but just 12 years later proposed a national day of
mourning and protest for mother’s of sons who killed sons of other mother’s.
She had come to regret her support of the Civil War and wanted July 4<sup>th</sup>
to be converted into a protest day by mother’s to ban future wars. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This didn’t go over that well, but the daughter of one of
her followers, Julia M. Jarvis, re-purposed the proclamation to celebrate her
own mother’s dedication to church and community. This caught on, and in 1912
Jarvis’ home state of West Virginia officially recognized Mother’s Day. Two
years later, President Woodrow Wilson declared that the second Sunday in May
should be a national observance of a Mother’s Day.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
But what has it got to do with your mitochondria? Well, you
owe your mom a debt of gratitude for every one of your mitochondria. All of yours came from
hers – Dad played no role in your cellular ATP factories. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Here's how it works. Your somatic cells (all your cells
except the eggs or sperm) have two copies of each chromosome, but we know that
your <a href="http://biologicalexceptions.blogspot.com/2012/04/life-outside-chromosome.html">chromosomes aren’t the only DNA in your cells</a>. Your mitochondria have
their own chromosome; it’s circular like the prokaryotic ancestor it came from
during endosymbiosis. How do you inherit that DNA?</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpnV-QzGWAVIey8w0lsSL9R3jIaPWVUPYGXwAhc_c1pI9CQK9xnPQYvFV8-FqYfoAZRZVyEzm_JX5zbrk_mGCri1L8qwBycGXQuXr1I6UeO_FOe0We051UwiWSyf0aSuf4i6ezXV5OUWny/s1600/2-sperm.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpnV-QzGWAVIey8w0lsSL9R3jIaPWVUPYGXwAhc_c1pI9CQK9xnPQYvFV8-FqYfoAZRZVyEzm_JX5zbrk_mGCri1L8qwBycGXQuXr1I6UeO_FOe0We051UwiWSyf0aSuf4i6ezXV5OUWny/s320/2-sperm.JPG" width="188" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 11pt;">In this
electron micrograph of the sperm you</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">can see the
dark nucleus which houses the </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">chromosomal
DNA. Above the acrosome, or </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">head, you
can see the mitochondria packed </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">into around
the tail proteins. Their ATP is </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">used to whip
the tail for locomotion.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span>
egg has loads of mitochondria, about a million in each <b>oocyte</b> (egg cell). On
the other hand, each sperm has only about 100. This makes sense, the body must
produce billions of sperm, but only a few eggs, so it has to ration the mitochondria to all those sperm cells.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The important issue is <u>where</u> the mitochondria
are located. The oocyte mitochondria are inside the egg, waiting for a single
sperm to enter and begin the process of making a new human (for example). All
the mitochondria of the sperm are located in the first part of the tail, called
the <b style="mso-bidi-font-weight: normal;">midpiece</b> or mitochondrial
sheath. This also makes sense, as it is the tail’s movement that propels the
sperm toward the egg, All of this tail wagging requires a great amount of ATP.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The sperm meets the egg and fuses with the oocyte membrane,
but not all of it enters the egg cell. Only the head, or <b style="mso-bidi-font-weight: normal;">acrosome </b>makes entrance; it has the haploid chromosomal DNA that is
your father’s contribution to your genetic makeup. The sperm midpiece, will all
its mitochondria remain on the outside of the egg and does not contribute to
you being you.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
That is how it came to be that you got all your mitochondria
from your mother! We all did. The process is called <b style="mso-bidi-font-weight: normal;">maternal inheritance of mtDNA</b>, and it is has implications for
tracking the history of human life. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhljhsklRFMAWaTrI6mUNMJgiB7LHSq0Jg2NYHq1n4iW_dkKJqoaelN6dRAU0mHbAjTK0_s6A_3R4-5oqmXI8BPw-CaZ9jmVpz_jeZ37hTSE22dT2_l9hc9Oj_7jqEQof0wxphC96fe04YV/s1600/3-mismatch.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhljhsklRFMAWaTrI6mUNMJgiB7LHSq0Jg2NYHq1n4iW_dkKJqoaelN6dRAU0mHbAjTK0_s6A_3R4-5oqmXI8BPw-CaZ9jmVpz_jeZ37hTSE22dT2_l9hc9Oj_7jqEQof0wxphC96fe04YV/s320/3-mismatch.jpg" width="255" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 11pt;">A journal
cover for the issue dedicated to DNA</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">repair
enzymes. Who says scientists don’t have </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">a sense of
humor? Actually, this may just have been</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">how one guy
showed up to the lab that day; his</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">mind was on
science, not fashion.</span></div>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
Mitochondrial DNA doesn’t change much over time, but it does
change. Every time your DNA replicates, mistakes are made. “To err is
mammalian,” and your <b style="mso-bidi-font-weight: normal;">DNA polymerase</b>
(polymer = long chain, and ase = enzyme that makes) is mammalian. Consider that
the DNA polymerase is adding nucleotides to a growing chain at a rate of about
1000/second – some mistakes are bound <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">to occur.</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Most of these mistakes are caught and fixed by a series of
proofreading and mismatch repair functions, but some mistakes get through. These
<b style="mso-bidi-font-weight: normal;">random mutations</b> often have no
effect on the function of the gene product, but if they aren’t fixed, they
become permanent and are passed on the next time the DNA is replicated.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Over time, the changes add up. The 50<sup>th</sup>
generation mtDNA necessarily looks different from the 1<sup>st</sup> generation DNA.
Mutations that hurt the function could very well prevent reproductive success
(the ability to mate and produce viable offspring), so the changes that we see
over time usually are the ones that have little effect on function.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This random mutation wouldn’t matter much if you got half
your mitochondria from Pop and half from Mom, there would be random passing on
of mitochondrial DNA and probably some recombination, so the 50<sup>th</sup> generation wouldn’t
look much at all like the first. But you get all of your mitochondria from Ma, and she
got hers from her ma, and she got hers from her ma, ….. so that there is a
straight line back in your family history.</div>
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkJs0MbUsx1L7abY377ZdPg_jCcbB6LVJbmRiORih8qI_r-rXPm7rthCHqxmhbJ_NmKO7i3mG7IoYbZvFY8R4bAg7kYIwIKUOMM11kNshn10Zn7iy6r4Oh5t5Y34kZp-1Y2E408IRgAfQ-/s1600/4-migration.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="165" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkJs0MbUsx1L7abY377ZdPg_jCcbB6LVJbmRiORih8qI_r-rXPm7rthCHqxmhbJ_NmKO7i3mG7IoYbZvFY8R4bAg7kYIwIKUOMM11kNshn10Zn7iy6r4Oh5t5Y34kZp-1Y2E408IRgAfQ-/s320/4-migration.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">The rate of
mutation and the pattern of mutation </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">in the mtDNA
can not only help us date mtEve, but </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">can help
track the migration of humans out of Africa </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">and around
the world. The numbers with a k = </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">thousands of
years ago.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span>
maternal inheritance of mtDNA allows scientists to trace family lineage through
molecular biology (to balance the sexes, you can trace paternal lineage through
the Y sex chromosome as well). In fact, with a large enough sample size, you
could literally see that all humans are related! Trace the changes in mtDNA
backwards far enough and they will all converge on a single female; the mother
of all mothers - “Mitochondrial Eve.” This isn’t the same as a Biblical Eve –
just the last female to whom we are all related. We don’t know who mtEve was,
where mtEve was, or when mtEve was because we don’t have enough samples from
enough generations. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The most current estimate is that mtEve lived about 200,000
years ago, although the timing is just that, an estimate. The sampling and math
are dependent on knowing the rate of mutation of the <b style="mso-bidi-font-weight: normal;">hypervariable regions</b> (part of the mtDNA that mutates faster than
the other parts) and knowing that this rate has been constant and predictable.
Does that sound like the biology you know? The assumption doesn’t invalidate
the idea of mtEve, it just makes sending her birthday card difficult. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Even if we don’t know who Eve was, we can talk about her
“daughters.” These are the unnamed females to whom we can trace back large
numbers of living and deceased humans. Geneticist Bryan Sykes wrote a book
called <i style="mso-bidi-font-style: normal;">The Seven Daughters of Eve</i> in
2001, but we now consider that we have really defined about 10-12 daughters. With
twelve daughters, there must have terrible fights over bathroom time!</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8xVldBpvNsAYzjeDDtXcPo0lnUegWNyIEw5HsusMDZ-5okJrYiHPf4EHIYu9I5j27RTypGrHSdVWPg9UL8rR4ntF8Tv5vnkGKj6x_coggwnGjLJmHeiPu1fYjT3VF_tzOYlvrnDFa3skJ/s1600/5-seven+daughters.tif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8xVldBpvNsAYzjeDDtXcPo0lnUegWNyIEw5HsusMDZ-5okJrYiHPf4EHIYu9I5j27RTypGrHSdVWPg9UL8rR4ntF8Tv5vnkGKj6x_coggwnGjLJmHeiPu1fYjT3VF_tzOYlvrnDFa3skJ/s320/5-seven+daughters.tif" width="276" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Bryan Sykes
named his seven daughters of Eve </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">based on the
first letter of the haplotype designation </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">each already
had. Example, haplotype U became </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Ursala – he must
have seen Bond girl Ursula Andress </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">in Dr. No
recently.</span></div>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Why</span>
would maternal inheritance of mtDNA be a good idea? Current theories
hypothesize that this a mechanism by which only genetically strong sperm will
reach the egg, and only genetically strong mitochondria will be inherited. With
only a few mitochondria in the sperm, they must perform well in order for the
sperm to reach the egg. If genetic mistakes have been made during meiotic
production of sperm, then chromosomal errors might be accompanied by
mitochondrial errors. A fast swimmer indicates a genome without harmful
mutations. So the strongest genes get to the egg.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
On the other hand, the effort to reach the egg means lots of
ATP production, which also means lots of oxygen produced by oxidative
phosphorylation. Oxygen can be damaging; the mitochondria probably aren’t in
good shape at the end of the race. The sperm may be like <a href="http://biologicalexceptions.blogspot.com/2012/02/do-you-drink-like-fish.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">salmon</span></a>. The strongest
make it up stream, but they end up so broken down that one trip is all they
get; the damage would prevent the next round of their sperm from being prime
material.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Why would evolution choose to pass on damaged paternal mitochondria
when you have perfectly fine maternal mitochondria laying around in the
hundreds of thousands. The chances are greater that the mother’s mitochondria
are normal at this point, so the paternal versions are denied entry. Makes
sense.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
But some organisms just have to rock the boat. Blue mussels
(family <i style="mso-bidi-font-style: normal;">Mytilidae</i>) and some
freshwater mussels have two different types of mtDNA, called F and M – how
original. The female passes on the F type to her sons and daughters, while the
males pass on the M type to just their sons. Called <b style="mso-bidi-font-weight: normal;">doubly uniparental inheritance</b> (DUI), females are homoplasmic (one
type and males are heteroplasmic (two types).</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Males are usually F type dominant in their somatic cells,
but M type dominant in their spermatozoa. The females must be F type dominant
in all cells, since they only have one type. The interesting part is that both
male and female embryos get M type mtDNA, but in those destined to be females,
the M type are degraded within 24 hours. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
A 2009 study shows that the sex determination and
inheritance of the male mtDNA are not coupled, and the female has complete
control over whether the male type will be inherited and maintained. But there
are occurrences of females with some M type, and males with only F type.
Therefore, maternal inheritance is more stringent than DUI ------ Or is it?</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjucuYnds_KyypCjM0d0OnsFMCHlqXRWzRQX0onfVdqfaD68xgLff0X194tGCCUn_ZUJzYStJxkZw6a25KU-L8__zi3qgvgmaYiWctrWbwJAt2rGM7hXJaDTcDzHm45LuThuenIPzNx_WTn/s1600/6-+egg.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="215" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjucuYnds_KyypCjM0d0OnsFMCHlqXRWzRQX0onfVdqfaD68xgLff0X194tGCCUn_ZUJzYStJxkZw6a25KU-L8__zi3qgvgmaYiWctrWbwJAt2rGM7hXJaDTcDzHm45LuThuenIPzNx_WTn/s320/6-+egg.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">This is a <i style="mso-bidi-font-style: normal;">Schistosoma mansoni</i> egg. It looks </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">like a
cartoon bubble; I keep expecting it to </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">say
something. <i style="mso-bidi-font-style: normal;">S. mansoni</i> is an exception
</span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">for
trematodes, it has two sexes (is <b>dioecious</b>), </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">whereas most
others are hermaphroditic. </span></div>
</td></tr>
</tbody></table>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">The function
of the spine on the egg is not known, </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">but it may help the
egg stick to the wall of the blood </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">vessel in
the host.</span></div>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">In some</span>
cases, like honeybees, mice, and a parasitic worm called <i style="mso-bidi-font-style: normal;">Schistosoma mansoni</i>, there can be “leakage” of paternal mtDNA into
the fertilized egg. Even in some mammalian species other than humans, including
sheep and mice, the tail of the sperm can penetrate the oocyte. This gives a
zygote with many copies of female mtDNA and a few copies of paternal mtDNA. For
some reason – I assume there is a reason, although I don’t know it -- this occurs
more in crossbreeding (<b style="mso-bidi-font-weight: normal;">interspecific breeding</b>
– between species), than when two animals of the same species are bred. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In the breeding of animals of the same species, if there is
paternal mtDNA present, it is degraded in the fertilized egg. Near the time of
birth, they might have only a trace of paternal mtDNA left, but the mechanism
by which this occurs is not known. During this time, there is the small chance
that male mtDNA could recombine with female mtDNA and gum up the workings of
strict maternal inheritance. In any case, there has been only one documented
case of a paternal mitochondrion in a child, and this case was clouded by
issues of infertility. Does this child feel disconnected from his great, great,
great, great grandmother?</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So much for animals - how about plant inheritance of
chloroplasts and mitochondria? Do they follow the same rules – let’s find out
next time.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=PLoS+One&rft_id=info%3Adoi%2F10.1371%2Fjournal.pone.0006976&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Paternal+mtDNA+and+Maleness+Are+Co-Inherited+but+Not+Causally+Linked+in+Mytilid+Mussels&rft.issn=&rft.date=2009&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Ellen+L.+Kenchington%2C+Lorraine+Hamilton%2C+Andrew+Cogswell1%2C+Eleftherios+Zouros&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Evolutionary+Biology%2C+Molecular+Biology">Ellen L. Kenchington, Lorraine Hamilton, Andrew Cogswell1, Eleftherios Zouros (2009). Paternal mtDNA and Maleness Are Co-Inherited but Not Causally Linked in Mytilid Mussels <span style="font-style: italic;">PLoS One</span> DOI: <a href="http://dx.doi.org/10.1371/journal.pone.0006976" rev="review">10.1371/journal.pone.0006976</a>
</span></div>
<div class="MsoNormal">
</div>
<br />
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">For more
information or classroom activities on maternal inheritance, mitochondrial Eve,
or fertilization, see – </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Maternal
inheritance – </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.ndsu.edu/pubweb/~mcclean/plsc431/maternal/maternal2.htm">http://www.ndsu.edu/pubweb/~mcclean/plsc431/maternal/maternal2.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.as.wvu.edu/~kgarbutt/QuantGen/Gen535_2_2004/Maternal_Inheritance_3.htm">http://www.as.wvu.edu/~kgarbutt/QuantGen/Gen535_2_2004/Maternal_Inheritance_3.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.dnalc.org/view/15977-Maternal-inheritance.html">http://www.dnalc.org/view/15977-Maternal-inheritance.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://hitechbloodstock.com/mitochondrialdna.htm">http://hitechbloodstock.com/mitochondrialdna.htm</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 10pt;">Mitochondrial
Eve – </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/nova/neanderthals/mtdna.html">http://www.pbs.org/wgbh/nova/neanderthals/mtdna.html</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.sciencedaily.com/releases/2010/08/100817122405.htm">http://www.sciencedaily.com/releases/2010/08/100817122405.htm</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://syllabus.med.unc.edu/yr4/gen/medhist/publish/mitochnotes.htm">http://syllabus.med.unc.edu/yr4/gen/medhist/publish/mitochnotes.htm</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.mhrc.net/mitochondrialEve.htm">http://www.mhrc.net/mitochondrialEve.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.archaeology.org/9609/abstracts/dna.html">http://www.archaeology.org/9609/abstracts/dna.html</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://io9.com/5879991/the-scientists-behind-mitochondrial-eve-tell-us-about-the-lucky-mother-who-changed-human-evolution-forever">http://io9.com/5879991/the-scientists-behind-mitochondrial-eve-tell-us-about-the-lucky-mother-who-changed-human-evolution-forever</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://blog.oregonlive.com/my-beaverton/2012/04/whos_your_mama_is_it_mitochond.html">http://blog.oregonlive.com/my-beaverton/2012/04/whos_your_mama_is_it_mitochond.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.discoveryeducation.com/teachers/free-lesson-plans/the-real-eve.cfm">http://www.discoveryeducation.com/teachers/free-lesson-plans/the-real-eve.cfm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www1.umn.edu/news/features/2012/UR_CONTENT_372562.html">http://www1.umn.edu/news/features/2012/UR_CONTENT_372562.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.actionbioscience.org/evolution/ingman.html">http://www.actionbioscience.org/evolution/ingman.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.designedinstruction.com/learningleads/mitochondrial-eve.html">http://www.designedinstruction.com/learningleads/mitochondrial-eve.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.aetv.com/class/admin/study_guide/archives/aetv_guide.0014.html">http://www.aetv.com/class/admin/study_guide/archives/aetv_guide.0014.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.pbs.org/wnet/facesofamerica/lessons/i-dream-of-genome/lesson-activities/202/">http://www.pbs.org/wnet/facesofamerica/lessons/i-dream-of-genome/lesson-activities/202/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://science.howstuffworks.com/environmental/life/evolution/female-ancestor.htm">http://science.howstuffworks.com/environmental/life/evolution/female-ancestor.htm</a></span><span style="font-family: "cambria"; font-size: 10pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<br /></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-family: "cambria"; font-size: 11pt;">Fertilization
- </span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.vivo.colostate.edu/hbooks/pathphys/reprod/fert/fert.html">http://www.vivo.colostate.edu/hbooks/pathphys/reprod/fert/fert.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://biology.about.com/od/genetics/a/aa040805a.htm">http://biology.about.com/od/genetics/a/aa040805a.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.visembryo.com/baby/1.html">http://www.visembryo.com/baby/1.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=6kGN2dcjNUY&feature=fvwrel">http://www.youtube.com/watch?v=6kGN2dcjNUY&feature=fvwrel</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.embryology.ch/anglais/dbefruchtung/akrosom02.html">http://www.embryology.ch/anglais/dbefruchtung/akrosom02.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin-bottom: .1pt; margin-left: 0in; margin-right: 0in; margin-top: .1pt;">
<span style="font-size: 10pt;"><a href="http://www.biology-online.org/articles/vitro_evaluation_frozen-thawed_stallion/sperm_oocyte_interactions.html">http://www.biology-online.org/articles/vitro_evaluation_frozen-thawed_stallion/sperm_oocyte_interactions.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com14tag:blogger.com,1999:blog-8136765635696545893.post-70404255848551948862017-12-28T06:00:00.000-05:002017-12-28T06:00:03.577-05:00When Is A Chloroplast Not A Chloroplast?<div class="MsoNormal">
Biology concepts – gravitropism, plastid, chloroplast,
chromoplast, amyloplast, leucoplast, malaria parasite</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Believe it or not, the way plant roots know to grow into the
dirt is related to photosynthesis! “How can this be?” you ask. Well, let’s talk
about it. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The cells in the tips of the plant rootlet respond
positively to gravity, called <b style="mso-bidi-font-weight: normal;">gravitropism</b>
(the older word for it is geotropism). If you lay a growing plant on its side,
the roots will respond by growing (turning) toward the gravity within 10
minutes. The mechanism for this stimulation involves tension and a plant
hormone called auxin. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglWMEejyd7cXjviOgoNAaILGeYwZXKUw1B67AE995hRRdlDnjW9aFf3iakZkKNVF7mzW3imycl7A0nGH7MA7Mp6dxg9oHYz_lG_YgLOqpqcnfaCixrCjX-cZX5oX3LV-mtXTbzJ4zOtriC/s1600/1-statolith.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="201" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglWMEejyd7cXjviOgoNAaILGeYwZXKUw1B67AE995hRRdlDnjW9aFf3iakZkKNVF7mzW3imycl7A0nGH7MA7Mp6dxg9oHYz_lG_YgLOqpqcnfaCixrCjX-cZX5oX3LV-mtXTbzJ4zOtriC/s320/1-statolith.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Auxin
is a growth hormone that gets redirected </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">in
the growing plant root. The statoliths settle </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">and
trigger the hormone to some cells more than </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">others.
Auxin means ”to grow” in Greek, but in </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">some
cases, like in gravitropism of roots, it </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">actually
inhibits growth.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The root</span>
cap (the cells at the tip of the root) have some specialized cells called <b style="mso-bidi-font-weight: normal;">statocyte</b> (stat = position, and cyte =
cell). Inside the statocytes are dense granules called <b style="mso-bidi-font-weight: normal;">statoliths</b> (lith = stone). The statoliths are made of densely
packed starch and are a specialized type of organelle called an <b style="mso-bidi-font-weight: normal;">amyloplast</b>, which is used in many plant
cells for storing carbohydrate in the form of starch (amylo = starch). The
statoliths are denser than the cytoplasm of the cell; they don’t just float
around, they settle out according to gravity. <br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Since the statoliths are connected to the membrane of the
cell by the cytoskeletal actin molecules, so when they settle toward gravity,
some cells in the membrane are stretched and some are compressed. This tension
signals the cells to change the number of receptors for the growth control
hormone <b style="mso-bidi-font-weight: normal;">auxin</b>. More tension (more
stretch) causes the auxin to move away, toward cells that are under less
tension. Auxin prevents cell enlargement and cell division, so those root tip
cells on the bottom receive more inhibition. Those on top enlarge more and
divide more, so the root turns down. If the root is already vertical, the
tension is equal in all directions, and the growth is equal in all directions –
the root gets thicker and longer.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Gravitropism is related to photosynthesis in that both
mechanisms involve chloroplasts, sort of. Root cells don’t perform
photosynthesis, they are underground, so they don’t have chloroplasts. But they
do have the amyloplastid statoliths, and these are related to chloroplasts. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Both amyloplasts and chloroplasts are specialized versions of the
plant organelle called the <b style="mso-bidi-font-weight: normal;">plastid</b>.
We asked last week about what defines a plant cell – maybe the plastid is it.
All plant cells have some plastids, but in different plant cells they may take
different forms, including chloroplasts, chromoplasts, leucoplasts, amyloplasts,
elaioplasts, or proteinoplasts, but they all start out as <b style="mso-bidi-font-weight: normal;">proplastids</b> (pro = early and plastos = form in Greek).</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwNNRTb0s0zsGJftD40kozSPB1WLgXMow_YPNKPEowLcPTWuOh6Rg7z2XiXOhncjN2rdb52jbcFcpaSBa-9GMZyqiDoifmFWZyYjndAZ0Wf58zSvBDYwLprRlecR505ikstmgaPqAxHihi/s1600/2-plastid.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwNNRTb0s0zsGJftD40kozSPB1WLgXMow_YPNKPEowLcPTWuOh6Rg7z2XiXOhncjN2rdb52jbcFcpaSBa-9GMZyqiDoifmFWZyYjndAZ0Wf58zSvBDYwLprRlecR505ikstmgaPqAxHihi/s1600/2-plastid.png" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 11pt;">Proplastids
are in every new plant cell. From there</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">they
can differentiate into other forms, including</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">the
chloroplast. Other plastids are used for storage</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">or
biochemical production. We will talk about statoliths </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">again
when we discuss proprioception.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">When a</span>
cell divides, each daughter gets its share of proplastids, and then depending
on the chemical signals that the daughter cell receives, the proplastid will <b style="mso-bidi-font-weight: normal;">differentiate</b> (from latin, means to
make separate) into the types of plastids that the cell needs. A proplastid can
become any type of plastid, and from time to time can change between forms as
the plant cell requires. Think of it as a sort of stem cell inside a plant cell
– if the cell happens to be in the stem of the plant, it could be a stem cell
inside a stem cell!<br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Proplastids become <b style="mso-bidi-font-weight: normal;">etioplasts</b>,
<b style="mso-bidi-font-weight: normal;">chloroplasts</b> or <b style="mso-bidi-font-weight: normal;">leucoplasts</b>. The etioplast is a sort of pre-chloroplast; a
chloroplast without chlorophyll. It is waiting to be stimulated by light energy
before it decides to spend all the energy it requires to make the chlorophyll.
The old science fair project about growing bean plants in the dark demonstrates
the etioplasts. The plants are white when grown in the dark, but bring them
into the light and they soon green up. The sunlight stimulates the etioplasts to
make chlorophyll, become full-fledged chloroplasts and start photosynthesizing.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiP7D62ILSYE0uXxDeORwXnE44bJC8z5JdCZwebWVIZAF2Dp23vD3y4WOdtW1r9d6BedQahKjeOM5j3hBIe-NOnLgVRGeAlGib2dL5plRZWd_braYNqXvkqBdCGHeTZL_rvyKjm5e3tlRp/s1600/3-chromoplast.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiP7D62ILSYE0uXxDeORwXnE44bJC8z5JdCZwebWVIZAF2Dp23vD3y4WOdtW1r9d6BedQahKjeOM5j3hBIe-NOnLgVRGeAlGib2dL5plRZWd_braYNqXvkqBdCGHeTZL_rvyKjm5e3tlRp/s1600/3-chromoplast.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">This
is a photomicrograph of the plastids of a </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">red
flower petal. The chromoplasts hold the </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">xanthocyanin
pigments, but we see it as a </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">continuous
color because they are so small.</span></div>
</td></tr>
</tbody></table>
<br />
<div class="MsoNormal">
If the proplastid does not differentiate toward a
chloroplast pathway (etioplast too) then it will become a <b style="mso-bidi-font-weight: normal;">leucoplast</b> (leuko = white). The leucoplasts don’t have color; they
become specialized for the storage of plant materials. If they store starch,
they are called amyloplasts. Lipid storing leucoplasts are called elaioplasts,
while protein storing plastids are called proteinoplasts. Each type serves a
crucial purpose in the cells they inhabit, and they can all interchange,
depending on the conditions the plant cell finds<span style="background-color: white;"> </span><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">itself in</span><span style="background-color: white;">.</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Even more important, leucoplasts that are not serving as
storage organelles have biosynthetic functions. They work in the production of
fatty acids and amino acids. Amino acids link together to from proteins, so
their synthesis is very important for plants. Plants must manufacture every
amino acid it needs, whereas we get many of ours in our diet. There are even some
amino acids that humans can’t make, called the essential amino acids. Of the
twenty common amino acids, nine of them must be taken in through our diet, and
some people with pathologies can’t make up to seven more. Plants don’t have
this luxury; all their amino acids must be made on site. Good thing they have
leucoplasts.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There is one other type of plastid that we haven’t talked
about, the one that is important for the Autumn tourist trade. Etioplasts and
chloroplasts can differentiate into <b style="mso-bidi-font-weight: normal;">chromoplasts</b>,
organelles that store pigments (colored molecules) other than chlorophyll.
Chlorophyll provides energy through photosynthesis, but they also have a cost.
The old saying, “It takes money to make money” applies to plants as well. It
takes energy to make chlorophyll, so it only pays to make chlorophyll when
there is ample sunlight to put through photosynthesis. When the days get
shorter, the profit margin for producing chlorophyll goes down, so the plant
just stops making it. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinIxW_3oipXOYjJiulWQ68mqZLmfnUT5dzYprDoGCW4VxzrOehX7VFqjXcPQZcnPhJX3W06BBAlbTRfD6wcags_3ZumhZPULmx36Yb4fqLg3-Pz5QVRl_uP30j0rbhCONJlGTnT1XKwLLj/s1600/4-smoker's+face.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinIxW_3oipXOYjJiulWQ68mqZLmfnUT5dzYprDoGCW4VxzrOehX7VFqjXcPQZcnPhJX3W06BBAlbTRfD6wcags_3ZumhZPULmx36Yb4fqLg3-Pz5QVRl_uP30j0rbhCONJlGTnT1XKwLLj/s400/4-smoker's+face.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">Twin
females were imaged after a lifetime of smoking
or non-smoking. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Can you guess who was
exposed to the oxygen radicals in cigarette </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">smoke
her whole adult life?</span></div>
</td></tr>
</tbody></table>
The oxygen produced in plant cells during photosynthesis can
damage many molecules; oxygen likes to react with other compounds and steal or
donate electrons. This oxidative damage can wreak havoc with the cells, just
look at the face of a long time smoker – the damage and aging process from the
oxidants in cigarette smoke will be evident. The chromoplast pigments, like
carotenoids (oranges and yellows) and xanthocyanins (reds and purples), can
serve as antioxidants, and protect the other cell structures from the damaging <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">effects of oxygen.</span><br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So the chloroplasts lose their chlorophyll in autumn and
could be called leucoplasts, but the chromoplasts still have the pigments that
had been masked by the greater number of chlorophyll molecules. The trees turn
magnificent colors and bring people from the cities to stay in bed and
breakfasts, and to purchase handmade scarves and way too much maple syrup and
apple butter. Economy and biology are so often interrelated.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Plastids are the quintescential plant organelles – no plant
cell is without them in some form (well O.K., there is one exception, we’ll
talk about that next week). But that still doesn’t mean that they define a
plant cell. Remember that algae are not plants, but they have chloroplasts, and
chloroplasts are one type of plastid. There is even a bigger exception in this
area; some of the apicomplexans.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Certain protozoal organisms, including the malaria parasite
(<a href="http://biologicalexceptions.blogspot.com/2012/05/biological-energy-crisis.html"><i style="background-color: white;"><span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto;">Plasmodium falciparum</span></i></a><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">)</span> contain an
organelle called an apicoplast. <i style="mso-bidi-font-style: normal;">P.
facliparum</i> or its ancestor obtained an algae cell by secondary <a href="http://biologicalexceptions.blogspot.com/2012/04/evolution-of-cooperation.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">endosymbiosis</span></a> (the
primary endosymbiotic event was the algae taking in a cyanobacterium), so the
apicoplast has a <u>four</u>, not two, membrane system. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCA2KKKq2r-4gGrqYtjQMCP8-wlB0_dmsGQdc_H6we6BrRznJ84Ii3gGCVE-8vMGGJUA1uNDOcG8xWUFVkXsJUoqbHaNedpHJOdSRnf1fveXsNK0beOU-usNA_M4-kx-zhBdygizUh_Da3/s1600/5-apicoplast.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCA2KKKq2r-4gGrqYtjQMCP8-wlB0_dmsGQdc_H6we6BrRznJ84Ii3gGCVE-8vMGGJUA1uNDOcG8xWUFVkXsJUoqbHaNedpHJOdSRnf1fveXsNK0beOU-usNA_M4-kx-zhBdygizUh_Da3/s320/5-apicoplast.jpg" width="225" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">The
apicoplast of the malaria parasite is of plastid </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">origin,
but it undergoes some unplant-like changes </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">during
cell division. Image D with the branched </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">apicoplast
is my favorite. Those in panel F will </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">grow
to look the one in panel A.</span></div>
</td></tr>
</tbody></table>
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The
apicoplast</span> does not perform photosynthesis; we aren’t exactly sure what
it does – but it is crucial for the survival of the parasite. It is located in
the front of the parasite (in the direction it moves and invades cells) and is
always close to the nucleus and the mitochondrion. This suggests some role(s)
in energy production and molecule synthesis. <br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
There is evidence that the apicoplast works in fatty acid and heme synthesis, like the leucoplast or in the production of
ubiquinones that are important for the electron transfer chain in the
mitochondria. There is also evidence that it is involved in FeS cluster
production, like the <a href="http://biologicalexceptions.blogspot.com/2012/05/many-paths-to-top-of-mountain.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">hydrogenosome</span></a>
and <a href="http://biologicalexceptions.blogspot.com/2012/05/biological-energy-crisis.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">mitosome</span></a>. Both
of these pieces of evidence show the interelationships of the endosymbiosed
organelles and the connection between energy production and energy use. Whatever
their functions are, if you destroy or inhibit it the malaria bug dies. As
such, it has been a popular target for anti-malarial drugs.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Malaria parasites cured of their apicoplasts
(cured means freed of) do not die right away. They just can’t invade any new cells and
therefore can’t complete their life cycle. This is why anti-apicoplast drugs
may be a boon to malaria treatment. The biosynthetic pathways in the apicoplast
are the targets of four recent drugs, but the primary way to stop malaria remains
the mosquito net. There is strong hope that a new vaccine, called RTS,S is a
light at the end of the tunnel for this killer of millions.</div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAqKHwNB5glsY-6c7C-85pqglD42kjJrSjrSQF0c1jNtPvcDF-JioZIUkQ7oIa2E02D6iztvnvJm0b3Rg_iECPeiTykh5XcOwaH5MDY1WoeJDbo0YWZs4A4o49ckfwTXT2jg6vBvUCLm4X/s1600/6-+Polykrikos+herdmanae.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAqKHwNB5glsY-6c7C-85pqglD42kjJrSjrSQF0c1jNtPvcDF-JioZIUkQ7oIa2E02D6iztvnvJm0b3Rg_iECPeiTykh5XcOwaH5MDY1WoeJDbo0YWZs4A4o49ckfwTXT2jg6vBvUCLm4X/s400/6-+Polykrikos+herdmanae.jpg" width="348" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-size: 10pt;">The
melanosome and the plastid have more in common. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">The
very rudimentary eye of some dinoflagellates </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">(dinos
= rotating, and flagellum = whip) has a melanin-like </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">molecule
in the pigment cup and the structure is called a </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">melanosome.
However, it is of plastid orgin. The picture</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">above
is of <i><span style="font-family: "cambria";">Polykrikos herdmanae. </span></i><i><span style="font-family: "cambria"; font-style: normal;">It has 8 transverse flagella, </span></i></span></div>
<i><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;">as well as the pigmented eyespot to detect light sources.</span></i></td></tr>
</tbody></table>
<br />
<i><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"></span></i><br />
One final thought on the plastid – an addition to the
exception of <a href="http://biologicalexceptions.blogspot.com/2012/03/cell-to-cell-tanning.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">melanosomes</span></a>.
We discussed a few weeks ago that melanosomes were the only organelles that
could move from cell to cell. Well, that isn’t exactly so. I held off on adding
the plastid to that list until we had discussed what a <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">plastid was</span>. <br />
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
A 2012 study at Rutgers University tested whether plastids
and mitochondria could move between plant cells. There results showed that
entire plastid genomes could be seen in recipient cells, and the fact that the
whole chromosome passed indicated that the plastid was probably moving from
cell to cell intact. But there was no movement of the mitochondria, so it is a
plastid (and melanosome) specific event.
The researchers hypothesize that this may be a way for plant cells to
repopulate damaged cells with working organelles. As such, it would be similar
to how mammalian stem cells can move mitochondria into damaged cells during
tissue repair. But that is another story.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
We have repeatedly talked about how the mitochondrion and
plastid can replicate on their own and then are portioned out to the daughter cells
when a parent divides. Can it really be that simple? I’ll bet there is a
definite mechanism, and I bet that mechanism has exceptions. Let’s look into
this next time.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Proc+Natl+Acad+Sci+U+S+A.+&rft_id=info%3Adoi%2F10.1073%2Fpnas.1114297109&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Cell-to-cell+movement+of+plastids+in+plants&rft.issn=&rft.date=2012&rft.volume=109&rft.issue=7&rft.spage=&rft.epage=&rft.artnum=&rft.au=Gregory+Thyssena%2CZora+Svaba%2C+and+Pal+Maligaa&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Structural+Biology">Gregory Thyssena,Zora Svaba, and Pal Maligaa (2012). Cell-to-cell movement of plastids in plants <span style="font-style: italic;">Proc Natl Acad Sci U S A. , 109</span> (7) DOI: <a href="http://dx.doi.org/10.1073/pnas.1114297109" rev="review">10.1073/pnas.1114297109</a></span>
</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">For
more information or classroom activties on plastids, gravitropism, or <i style="mso-bidi-font-style: normal;">Plasmodium falciparum</i> see:</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Plastids
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://teachersnetwork.org/ntol/lessons/plantcell/index.htm">http://teachersnetwork.org/ntol/lessons/plantcell/index.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://pubs.acs.org/doi/abs/10.1021/ed074p1176A">http://pubs.acs.org/doi/abs/10.1021/ed074p1176A</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://theclassroomguide.com/category/sixth-grade-science-lessons/">http://theclassroomguide.com/category/sixth-grade-science-lessons/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://sln.fi.edu/qa97/biology/cells/cell4.html">http://sln.fi.edu/qa97/biology/cells/cell4.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.bcb.uwc.ac.za/Sci_Ed/grade10/cells/plastids.htm">http://www.bcb.uwc.ac.za/Sci_Ed/grade10/cells/plastids.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.nature.com/scitable/topicpage/the-origin-of-plastids-14125758">http://www.nature.com/scitable/topicpage/the-origin-of-plastids-14125758</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.pnas.org/content/109/7/2439.full">http://www.pnas.org/content/109/7/2439.full</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://library.thinkquest.org/27819/ch3_9.shtml">http://library.thinkquest.org/27819/ch3_9.shtml</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.sivabio.50webs.com/plastids.htm">http://www.sivabio.50webs.com/plastids.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www2.mcdaniel.edu/Biology/botf99/cellstructure/plastids.html">http://www2.mcdaniel.edu/Biology/botf99/cellstructure/plastids.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www2.mcdaniel.edu/Biology/botf99/cellstructure/plastids.html">http://www2.mcdaniel.edu/Biology/botf99/cellstructure/plastids.html</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Gravitropism
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://herbarium.desu.edu/pfk/page8/page9/page9.html">http://herbarium.desu.edu/pfk/page8/page9/page9.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.sciencebuddies.org/science-fair-projects/Classroom_Activity_Teacher_RootsGravity.shtml">http://www.sciencebuddies.org/science-fair-projects/Classroom_Activity_Teacher_RootsGravity.shtml</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p034.shtml">http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p034.shtml</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://oldintranet.puhinui.school.nz/Topics/Plants/Ecosystem_Space/xpt1.html">http://oldintranet.puhinui.school.nz/Topics/Plants/Ecosystem_Space/xpt1.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/gravitropism/rootgrav/graviroot.html">http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/gravitropism/rootgrav/graviroot.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.nature.com/emboj/journal/v18/n8/abs/7591633a.html">http://www.nature.com/emboj/journal/v18/n8/abs/7591633a.html</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt;">207.62.235.67/case/biol215/docs/<b style="mso-bidi-font-weight: normal;">roots</b>_<b style="mso-bidi-font-weight: normal;">gravity</b>.pdf</span></cite><span style="font-size: 11pt;"></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<i style="mso-bidi-font-style: normal;"><span style="font-size: 11pt;">Plasmodium falciparum</span></i><span style="font-size: 11pt;"> – </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.yourgenome.org/teachers/managingmalaria.shtml">http://www.yourgenome.org/teachers/managingmalaria.shtml</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.cpet.ufl.edu/icore/.../PDF/Malaria%20classroom%20activity.pdf"><span style="font-style: normal;">www.cpet.ufl.edu/icore/.../PDF/Malaria%20classroom%20activity.pdf</span></a></span></cite></div>
<div class="MsoNormal">
<span style="font-size: 11pt;"><a href="http://malaria.wellcome.ac.uk/doc_WTD023865.html">http://malaria.wellcome.ac.uk/doc_WTD023865.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.parasitesinhumans.org/plasmodium-falciparum-malaria.html">http://www.parasitesinhumans.org/plasmodium-falciparum-malaria.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://bioweb.uwlax.edu/bio203/s2007/augustin_laur/">http://bioweb.uwlax.edu/bio203/s2007/augustin_laur/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.icp.ucl.ac.be/~opperd/parasites/ancient_dna.html">http://www.icp.ucl.ac.be/~opperd/parasites/ancient_dna.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.tulane.edu/~wiser/malaria/cmb.html">http://www.tulane.edu/~wiser/malaria/cmb.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.searo.who.int/en/Section10/Section21/Section340_4269.htm">http://www.searo.who.int/en/Section10/Section21/Section340_4269.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://emedicine.medscape.com/article/221134-overview">http://emedicine.medscape.com/article/221134-overview</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com5tag:blogger.com,1999:blog-8136765635696545893.post-7398221109089512742017-12-21T06:00:00.000-05:002017-12-21T06:00:00.164-05:00The Life Of The Party<div class="MsoNormal">
Biology concepts – <u>plant adaptations</u>, <u>osmosis</u>, <u>parthenogenesis</u></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Last week we discussed the biological implications of an old Christmas carol. Today’s post is a hodgepodge of holiday biology, but we can still find some exceptions.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEje8lwhcPYA7pJqyVVvH8cWmIDHD_n91AT6IbjPWvtUI-plQZD9qb0URt4aQgFcPs4H6jtVpxBJA970FsqGdTu5eqaSU8cdrIKmk24_KFH48bQTYsAQkPtuQX0zBn0m3LT9eF21BvVSrrt3/s1600/trees.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="211" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEje8lwhcPYA7pJqyVVvH8cWmIDHD_n91AT6IbjPWvtUI-plQZD9qb0URt4aQgFcPs4H6jtVpxBJA970FsqGdTu5eqaSU8cdrIKmk24_KFH48bQTYsAQkPtuQX0zBn0m3LT9eF21BvVSrrt3/s320/trees.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 11pt;">From a distance, spruce, fir, and pine Christmas </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">trees look similar. The differences are mostly in </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">the needles, both shape and number.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<b>Christmas trees</b> – There are many different types of trees used for Christmas, but they are all evergreens. This is the reason they were used in the first place. The tradition sprung from old pagan ceremonies that reminded us that spring would come and there would be a rebirth of greenery. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Evergreens have a thick wax coating on their needles (these are actually their leaves). This adaptation, as well as the low surface area of each leaf, helps to reduce water loss during the arid winter.<br />
<br />
The resin of evergreens is higher in sugar than in other trees species. This keeps the liquids in the tree from freezing solid during the cold months. The higher sugar content oozes from the bark and at the collars of the branches, and is very sticky (picture Chevy Chase in Christmas Vacation). </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Evergreen is a characteristic not a botanical grouping. They tend to photosynthesize all winter long, given enough water and sunlight. In deciduous trees there are hormonal (phytohormonal) signals that induce cleavage of the leaves from the stems (<b>abscission</b>) when there is not enough sunlight to justify making chlorophyll. In evergreens, there is some of this signal present, and pines do lose leaves in the winter, just not all of them. When cut and kept indoors, the abscission signal is increased, and together with the reduced water – all the needles end up on your carpet.</div>
<div class="MsoNormal">
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
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<span style="font-size: 11pt;">The leaves of cedar Christmas trees</span></div>
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<span style="font-size: 11pt;">look different from other evergreens.</span></div>
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<span style="font-size: 11pt;">If you choose a red cedar, just remember</span></div>
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<span style="font-size: 11pt;">that there is actually no evidence that </span></div>
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<span style="font-size: 11pt;">they keep moths away.</span></div>
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The groups of trees used for Christmas are members of the conifers – cedar, fir, and pine, and spruce. In general, pines have two or three needles coming from the same place on the twig, while fir and spruce usually have just one. To tell fir from a spruce, try to roll a needle in your fingers; if flat and won’t roll, it is probably a fir, but if it is four sided and can be rolled, it is a spruce. Cedars look different from the other three, they have scale-like leaves and ball cones, and their bark is more splintered.</div>
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<b>Christmas cactus</b> – This is a small genus of plants, comprised of two groups, the truncata and the buckleyi. In the wild, they grow on other plants (<b>epiphytic</b>) or on rocks (<b>epilithic</b>). They don’t have leaves, common in cacti, their flattened green stems serve as their photosynthetic elements. They occur in naturally in eastern Brazil, along the coast of the Atlantic Ocean. Those for sale in the U.S. are cultivars, bred for hardiness and different colors, different plants will bloom in red, yellow orange, or pink.</div>
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<span style="font-size: 11pt;">Thanksgiving cactus stem is shown on the </span></div>
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<span style="font-size: 11pt;">top, while the bottom stem is from a </span></div>
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<span style="font-size: 11pt;">Christmas cactus.</span></div>
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In Brazil, the cacti are called May Flowers, reflecting the month in which they bloom in the Southern Hemisphere. In the northern latitudes, they flower from November through January, depending on the cultivar. This presented a classic opportunity for commercialization.</div>
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You might want to look at your Christmas cactus a little more closely; you might actually have a <i>truncata</i> when you think you have a <i>buckleyi</i>. The Christmas cactus has stem segments that are rounded, with more symmetric points. The flowers hang down low and their pollen is pink. These flowers generally bloom later and these <i>buckleyi</i> cultivars therefore termed the Christmas cactus.</div>
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<span style="font-size: 11pt;">The yellow pollen on the left is characteristic of a Thanksgiving </span></div>
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<span style="font-size: 11pt;">cactus. The pink pollen of the flower on the right is typical of </span></div>
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<span style="font-size: 11pt;">the Christmas cactus.</span></div>
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In contrast, <i>truncata</i> cacti have much sharper stem segments. If it hurts to prune your cactus, you may have one of these. The flowers stay closer to horizontal, or even rise up on the plant. The pollen grains are yellow, so there are several ways to tell these plants apart. Perhaps the best way is by the blooming time. The <i>truncata</i> will bloom closer to the end of November. For this reason, they are often called Thanksgiving cacti. Still think you have a Christmas cactus?</div>
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<b>Fruitcake</b> – I am an unapologetic fruitcake fanatic. To everyone who isn’t - stop making fun and just send them to me. </div>
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<span style="font-size: 11pt;">Fruitcake! It may be my favorite </span></div>
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<span style="font-size: 11pt;">holiday treat. </span></div>
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The biology of fruitcake is based on bacteria, or more correctly, the lack of bacteria. The candied fruits used in fruitcake are not just dried, they are preserved. For many centuries, fruits were precious commodities, especially in the winter. The vitamin C and other nutrients were needed for good health, but spoilage kept most people from having them during the colder weather. </div>
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Meats were preserved with salt, called curing, since the days of the ancients. Fruits, on the other hand, don’t taste so good when salt cured. It turned out sugar that could preserve fruits just as salt cured meats. Either liquid syrup or crystalline sugar would do the job, but sugar was very costly. Honey could do the job, but not as well, and it wasn’t much more available. Therefore, preserved fruits were a luxury for some period of time.</div>
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With the advent of sugar beet production in the Americas in the late 1500’s and the resulting availability of sugar in Europe, there was a candied fruit glut in Europe. It became more common to use them in baking. Italian pannatone, and fruitcakes were common uses.</div>
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So how do salt and sugar preserve foods? It all has to do with water. Bacteria need water to survive; if you remove the water, you stop (or at least slow) bacterial growth. An osmotic gradient is set up when cells are placed in high salt (hypertonic) or high sugar environment. If the salt or sugar content is higher outside the cell, it means that the water concentration is higher inside the cell. </div>
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<span style="font-size: 11pt;">In osmosis, water flows from where there</span></div>
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<span style="font-size: 11pt;">is little solute toward where there is</span></div>
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<span style="font-size: 11pt;">much solute. In hypertonic solution, </span></div>
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<span style="font-size: 11pt;">this means water leaves the cell.</span></div>
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Water will flow from areas of high concentration to areas of low concentration, just as the salts and sugars will. This is diffusion, but in the case of water it is called osmosis (<a href="http://biologicalexceptions.blogspot.com/2011/11/plants-that-dont-sleep-will-take-dirt.html">Plants That Don't Sleep Well</a><span style="background: none repeat scroll 0% 0% yellow;"></span>). The solvent (water) and solutes (those things dissolved in the solvent) try to balance their concentrations, so water flows out of the cell and salts or sugars flow in. The result is pandemonium, chemical reactions are not possible under these conditions, and the organism either dies or goes into stasis. </div>
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Dehydration by salt and sugar work in several ways. One, removing water through osmotic pressure will turn the bacteria, fungi, and parasites already on the food to dried up corpses by pulling out their water. Second, the lack of water in the preserved food stops bacteria and other microbes that might land on them from propagating; no water, no cell division. </div>
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Third, the high salt or sugar concentrations, even with some water present, limits the species of organisms that could grow there. Only a few microbes, called <b>halophiles</b> (hal = salt, and phile = lover) can grow in high salt environments. Similarly, honey is only about 30% water, so not many bacteria can grow in this low water/high sugar environment (but some important bacteria can, so don't give raw honey to infants). Finally, the loss of water in the foodstuffs reduces the oxidation reactions that might take place to age the food. Fats are especially susceptible to oxidation, they go rancid in not too long. The curing of meats slows this process, but is less a problem in fruits due to the low fat content. </div>
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Those fruitcakes deserve a little more credit, don’t they? And by the way, fruitcakes are not the doorstops everyone thinks they are, they actually float in water.</div>
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<b>Virgin birth</b> – I will only touch on this subject, as the blog will soon be delving into a series of stories on mating and reproduction. There are many species of animal that can give birth to viable young without mating. This is called <b>parthenogenesis</b> (partheno = virgin, and genesis = birth). </div>
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<span style="font-size: small;">In 2005, a komodo dragon in a zoo laid some</span></div>
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<span style="font-size: small;">eggs. No big deal, except she hadn’t been housed </span></div>
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<span style="font-size: small;">with a male for 2 years! Apparently, they can </span></div>
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<span style="font-size: small;">reproduce sexually, or by parthenogenesis if</span></div>
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<span style="font-size: small;">no males around. This has changed how</span></div>
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<span style="font-size: small;">komodos are housed in zoos.</span></div>
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Parthenogenesis occurs when the unfertilized egg receives the messages necessary to begin to divide and form an embryo. The offspring have only their mother’s DNA with which to work, so they are all clones and all female. The egg does have two copies of the chromosomes, but this can occur in two ways. If the egg is haploid but undergoes chromosome doubling, the resultant offspring is a half-clone of the mother. But if the egg is produced only by mitosis, with no meiotic event to result in a haploid gamete, then the offspring is a full clone. </div>
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Many species use parthenogenesis exclusively, or in response to environmental or population conditions. Whiptail lizards, as well as aphids and some plants, are famous for undergoing parthenogenesis. No cases of mammalian parthenogenesis have been documented in the wild, but stem cells have been developed by parthenogenesis in the laboratory. Anyway, if the Christmas story was going to rely on parthenogenesis, then Jesus should have been a baby girl. </div>
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<span style="font-size: 11pt;">Mistletoe is an evergreen that grows </span></div>
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<span style="font-size: 11pt;">on other plants. It can draw water</span></div>
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<span style="font-size: 11pt;">from the host even in winter. It also</span></div>
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<b>Mistletoe</b> – These are evergreen, hemi-parasitic plants that grow in many parts of the world. They have photosynthetic leaves, so they produce their own carbohydrates and energy, but they rely exclusively on their host tree for water and minerals. The mistletoe roots bore into the host bark and vascular tissue to obtain the water and minerals it needs.</div>
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The mistletoe can serve to hurt the host plant, especially if it grows too well, but they can also help the host. Junipers that harbor mistletoes produce more berries than those without. This is due to the large number of birds that come to eat the mistletoe berries; the juniper takes advantage. This makes it hard to determine of the symbiosis of mistletoe/host is parasitism or perhaps mutualism.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7Ov9CtQyyo7hyphenhyphenArwgrtNPkKxIJxAb7uuCcVPIQLYl3q-PpVU2kTsGvJ1eW8YgikMihWI8ihxbOP6jy0pQ9wod5ug3xQHfLHZ9uT9NMOa6emsg8uzzzo4vmnZs4MkQ9wmjFORCVYCVykB9/s1600/mistle+seed.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="91" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7Ov9CtQyyo7hyphenhyphenArwgrtNPkKxIJxAb7uuCcVPIQLYl3q-PpVU2kTsGvJ1eW8YgikMihWI8ihxbOP6jy0pQ9wod5ug3xQHfLHZ9uT9NMOa6emsg8uzzzo4vmnZs4MkQ9wmjFORCVYCVykB9/s200/mistle+seed.jpg" width="200" /></a></td></tr>
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<span style="font-size: 11pt;">As the berry passes through the bird,</span></div>
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<span style="font-size: 11pt;">it releases sticky cellulose fibers that</span></div>
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<span style="font-size: 11pt;">help the seed stick to an unfortunately</span></div>
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The name, mistletoe, is not something commonly brought up at a holiday party. From the Old English word, “mistiltan,” the name tells it all. Birds eat the fruit and seeds of the plant and some of them pass through the GI tract unaltered. When excreted (mistil means dung), the sticky seeds may germinate on a limb (tan means branch). Interesting, but try not to mention it over a bowl of holiday punch.</div>
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The white berries of the mistletoe played a role in the 18<sup>th</sup> century Christmas kissing tradition. In Scandinavia, the maid under the mistletoe could be kissed, but the gentleman had to pull off a berry each time. While the berries were gone, the kissing privilege was lost. </div>
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Next time we will finish our stories on sleep and activity by talking about introduced species. Then we will start a series of posts on the incredible worlds of water and salts in biology. Our fruitcake discussion above may serve as a great introduction, but it is just the tip of the iceberg.<br />
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<span style="font-family: "cambria"; font-size: x-small;">The concepts discussed here will be discussed in more detail in other posts. Resources will be provided on those occasions.</span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com11tag:blogger.com,1999:blog-8136765635696545893.post-33340708316808871852017-12-14T06:00:00.000-05:002017-12-14T06:00:00.327-05:00It’s A Plant World, We’re Just Living In It<div class="MsoNormal">
Biology concepts – cell walls, chloroplasts, myco-heterotrophs,
holoparasites, </div>
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Life on Earth is easy. It can be boiled down to three sentences. “The mitochondria and the chloroplasts are, in a fundamental
sense, the most important things on Earth. Between them, they produce oxygen
and arrange for its use. In effect, they run the place.” Lewis Thomas wrote
this in his award winning book, The Lives Of The Cell: Notes Of A Biology
Watcher, in 1975. </div>
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<br /></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0dttQUj96GNaHd6jutlBSp8ZH9V9A1J5FIrOsg4b1GWndhFVpaBAeplLAlDPoSpEXZE2vVNjn_143rVMU7EaHQD_KXuGfPEZliqBBr0gLDAuf5zteGHkLq0t0PKXyjBO-7Tjf7Wg34X5s/s1600/1-+chloro+mito.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj0dttQUj96GNaHd6jutlBSp8ZH9V9A1J5FIrOsg4b1GWndhFVpaBAeplLAlDPoSpEXZE2vVNjn_143rVMU7EaHQD_KXuGfPEZliqBBr0gLDAuf5zteGHkLq0t0PKXyjBO-7Tjf7Wg34X5s/s400/1-+chloro+mito.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">Nature’s carbon recycling center. The sun’s energy
is used to </span></span><br />
<span class="assemblygist"><span style="font-size: 10pt;">polymerize carbon (CO<sub>2</sub>) into
carbohydrates (CHO) and releases </span></span><br />
<span class="assemblygist"><span style="font-size: 10pt;">oxygen (O<sub>2</sub>). Then the
mitochondria use the O<sub>2</sub> to break down </span></span><br />
<span class="assemblygist"><span style="font-family: "cambria"; font-size: 10pt;">the CHO,
resulting in chemical energy (ATP) and carbons (CO<sub>2</sub>) </span></span><br />
<span class="assemblygist"><span style="font-family: "cambria"; font-size: 10pt;">ready to
be polymerized again.</span></span>
</div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">He was so right - for the organisms that use them. I guess he didn't consider the exceptions. T</span>hese two organelles mesh seamlessly in their functions. One
produces carbohydrate and oxygen, while consuming carbon dioxide. The other
consumes carbohydrate and oxygen and produces carbon dioxide. The ultimate
recyclers. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
If these two organelles are the most important things for
life, then doesn’t that make plants the kings of life on Earth, since they have
both chloroplasts and mitochondria? Makes you feel a bit more humble now about
your place in world, doesn't it.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
However, this brings up an essential question – and the main
focus of today’s topic and exceptions. What makes a plant cell a plant cell?
Green algae have chloroplasts and mitochondria, but they aren’t plants, they
belong to the kingdom <i>Protista</i>. We
have discussed the sea slug, <a href="http://biologicalexceptions.blogspot.com/2011/08/biological-hybrids-diet-to-end-all.html" target="_blank">E. chlorotica, and its ability to photosynthesize</a> – it is certainly not a
plant. So what makes a cell a <u>plant</u> cell?</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Leaving the chloroplast out of the equation for a minute,
you could argue that a plant cell is one with a cell wall <u>and</u> cell membrane.
That surely separates them from animal cells, since animal cells only have the cell
membrane. But many bacteria, archaea, fungi, and algae have cell walls. If the
argument is refined to define a plant as having a certain kind of cell wall,
then we must look a little closer. Many cell walls are made of sugars,
but are plant cell walls unique in their constituents?</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1SmEPQXeytMf2H3hYyI_VnpovUOYCdkyjnbZANp3GSOLwngwhsaQ9n3je01fxV5rAgPgyHgJ-RlP2ZI_qmk8zlKod_N8GmQjlZVtlN3N9FLIc001R3rf62138W2CAyysZ8gQiS2kuOILd/s1600/2-+even+better+cellwall.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1SmEPQXeytMf2H3hYyI_VnpovUOYCdkyjnbZANp3GSOLwngwhsaQ9n3je01fxV5rAgPgyHgJ-RlP2ZI_qmk8zlKod_N8GmQjlZVtlN3N9FLIc001R3rf62138W2CAyysZ8gQiS2kuOILd/s400/2-+even+better+cellwall.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">True bacteria have two large groupings, Gram+ and
Gram -,</span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">based on their cell wall structures. The gram stain
sticks to </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">the peptidoglycan layer, so the thick layer on G+
bacteria make </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">them stain deeply. The <b>lipopolysaccharide </b>(LPS) layer of
the G- </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">species keeps them from staining, and is highly toxic.</span></span><br />
<span class="assemblygist"><span style="font-size: 10pt;"><b>Endotoxin</b> (LPS) and causes about 70% of septic shock cases. </span></span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Bacteria
cell</span> walls are made of <b>peptioglycan</b> (peptido = amino acid containing,
and glycan = polymer of two sugars). One of the two components is always <i>N</i>-acetylmuramic acid, and the other is
often poly-<i>N</i>-acetylglucosamine, but
other things can be included as well. The exception is the <i>Mycoplasma</i>, a group of small bacteria that don’t have a cell wall
at all. Since many antibiotics function by disabling the bacterial cell wall or
preventing its formation, they don’t work against mycoplasma infections like <i>M. genitalium</i>, which a 2011 study linked
to pelvic inflammatory disease in women.<br />
<br />
<div class="MsoNormal">
Fungal cell walls are also made of a polysaccharide (poly =
many, and saccharide = sugar), in a polymer called chitin. Chitin is also the
rigid polymer that makes so many insects crunch when you step on them. Chitin
cell walls are defining for fungi, as many cellulose containing cell wall fungi
have been moved out of the kingdom of Fungi. But this still doesn’t tell us
what is unique to plant cell walls. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Plant cell walls contain cellulose, and is complex. Plant
cell walls can contain up to three layers, with different sugars involved,
including cellulose, hemicellulose, and pectin, and lignin. Lignin is a more
rigid polysaccharide that gives strength. It is what makes bark hard, protective,
and water resistant.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYf3lRX6HZvpH7VB98OPmv6gKAJw072zdeRQZ4RbpSM0pq35mc8ygJ-Y5RoghegYkLOOPDdF1RNXx26STVAXLyrI_6mMrtO2YxdUti9jrK9v0sDeCNKmT9Q6iXt1-dPuXJWzR_x91p4sNF/s1600/3-starchcellu.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="305" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYf3lRX6HZvpH7VB98OPmv6gKAJw072zdeRQZ4RbpSM0pq35mc8ygJ-Y5RoghegYkLOOPDdF1RNXx26STVAXLyrI_6mMrtO2YxdUti9jrK9v0sDeCNKmT9Q6iXt1-dPuXJWzR_x91p4sNF/s320/3-starchcellu.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 10pt;">If the hydrogens (H) bound to the #1 and #4
carbons </span><span style="font-family: "cambria";"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 10pt;">up on the same side, the polymer is starch.
If they </span><span style="font-family: "cambria";"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 10pt;">are on different sides, the polymer is
cellulose. </span><span style="font-family: "cambria";"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 10pt;">We can digest starch: we can’t digest
cellulose. </span><span style="font-family: "cambria";"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 10pt;">Plants make both – the part we can’t digest
we call</span><span style="font-family: "cambria";"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 10pt;">dietary fiber. </span><span style="font-family: "cambria";"></span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Cellulose</span>
is made of a chain of glucoses, yet we can’t digest it. The number one carbon
in glucose has an –H that is sticking up or down. If the –H sticks “down”,
then it is an alpha glucose. If it sticks “up”, then it is a beta-glucose.
Cellulose is linked chains of beta-glucose. Starch is linked chains and
branches of alpha-glucose. Just that difference in –H position determines if
it is food for us or not. Herbivores have the enzymes (and bacteria) to digest
cellulose, but not us.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So is it the inclusion of cellulose that makes a plant cell
wall unique? Well, no. Algal cells also use cellulose in their cell walls. You
might try to argue that algae are plants, since many of them also have chloroplasts
and are primary producers – but you would be wrong. Algae can be unicellular
(although they can also be multicellular) while plants are all multicellular.
Algae don’t have specialized reproductive cells or parts like plants do; algae
reproduce by spore or from broken parts of themselves. Finally, DNA analysis
shows that while plants and algae are <b>monophyletic</b>
(one ancestor), they diverged from one another long ago.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Then there is the issue that not every plant cell has a cell
wall. In <b>angiosperms</b> (angio = chest
or vessel, and sperm = seed; plants with enclosed seeds and flowers), the
gamete (sex) cells of the male in the pollen and the gamete cells of the female
in the ovary do not have cell walls, at least not on all sides. The ovary
contains the <b>ovules</b> (latin for small
egg), and the pollen contains the sperm cells and the tube cell, that forms the
pollen tube and delivers the sperms cells to the ovules. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
After the ovules are fertilized by the sperm cells of the
pollen, the ovules form the seeds, and the ovary forms the fruit. From here on
in, all the daughter cells will have cell walls. For fertilization, it would make sense that the involved cells would not have a cell wall that would just get in the way of love. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLP0Wy-zF36HJntnpHWTtJrZ_ksrt_9Wv57P9cHyILcWfyYz-H3_vhyphenhyphenI9H6iep6BC8kIjbodIN5T-Tfx8Agl6t-a8PkyIXOEvDNdgGXb9sX945MNB_D_V8eNDsKPKyt4e5jCR4tnM6tMiF/s1600/cycas+revulta.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLP0Wy-zF36HJntnpHWTtJrZ_ksrt_9Wv57P9cHyILcWfyYz-H3_vhyphenhyphenI9H6iep6BC8kIjbodIN5T-Tfx8Agl6t-a8PkyIXOEvDNdgGXb9sX945MNB_D_V8eNDsKPKyt4e5jCR4tnM6tMiF/s320/cycas+revulta.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">The Sago Palm isn’t a palm, but is one of the most</span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">primitive plants that reproduces with seeds. It </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">presents a problem to pet owners because every part </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">is toxic to pets, but it tastes good to them. They
don’t </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">know not to eat it; then they bleed to death.</span></span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">And
even</span> weirder, not all plants use just this strategy. Cycads (like the
sago palm, which isn’t really a palm at all), and gingko biloba plants have
sperm cells with flagella, long projections that whip and move them along,
hopefully toward an egg cell. They don’t use a tube cell or pollen tube; these
plant cells without cell walls swim. Plant cells that move, now
there is an exception worth noting! Some more primitive bryophyte plants
(liverworts, mosses) also have motile sperm, but the cycads and gingko are the
only examples of seed plants with motile cells.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So cell walls aren’t a defining characteristic of plant
cells either. Maybe it is the chloroplast that defines a plant cell --- maybe not.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
As you can guess, there are exceptions going both ways.
There are organisms that have chloroplasts that aren’t plants, namely the
algae. But a more interesting exception are many of the protozoan Euglenids. <i>Euglena gracilis</i> is a prototypical
euglenid that can produce carbohydrate by photosynthesis. However, most euglenids can
also eat things, which makes them both autotrophic and heterotrophic. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
As for the other direction, there are many plants that don’t
have chloroplasts. Of the roughly 350,000 different species of plants on earth,
almost 3000 of them are non-photosynthetic. Therefore, the most common characteristic that
people use to tell a plant from a non-plant (photosynthesis by chlorolplasts) isn’t true for almost 1% of the species on Earth. That is a pretty
big exception. That would be like saying 1% of people on earth don’t have a
brain! O.K., maybe that's a bad example.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdL75w0gtO_mzisrWLTsConGyKxIeAhHQpvhAiOEO7av1Cn2ZmtSZKyFwWTJcH73-KyJ5BSM1OO4hTiLrHRB_22qrdON-TuPXJjfMOMk2tgwI5dRxCmL4K66HqLltQVU2pXr3GlHXXx7jl/s1600/indian+pipe.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgdL75w0gtO_mzisrWLTsConGyKxIeAhHQpvhAiOEO7av1Cn2ZmtSZKyFwWTJcH73-KyJ5BSM1OO4hTiLrHRB_22qrdON-TuPXJjfMOMk2tgwI5dRxCmL4K66HqLltQVU2pXr3GlHXXx7jl/s320/indian+pipe.jpg" width="255" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">Indian Pipe is Monotropa Uniflora. Monotropa means </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">one turn, and uniflora means one flower. The plant
is </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">called the ghost plant – obvious, or the corpse
plant – </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">because it turns black as it matures. This naming
thing </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">is easy!</span></span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Indian
pipe</span> (<i>Montropa uniflora</i>, or
ghost plant) is one such plant. Related to the blueberry of all things, the
ghost plant has gone its own way and become parasitic. It garners its nutrients
and energy from the tissue of another plant. The roots of the Indian pipe
penetrate the rhizoids (root-like projections) of certain types of fungi and
sponge off their hard work. In fact, the fungi themselves are symbiotic, having
invaded the roots of certain pine tree species.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The fungus and tree live together in a mutualistic
relationship, making the fungus a <b>mycorrhizal</b>
(myco = fungus and rrhizal = root) variety. The tree supplies the fungus with
carbohydrate, and fungus supplies the tree with mineral nutrients. However,
Indian pipe does not respect this mutualism and is a parasite of the fungus,
taking some of the carbohydrate supplied by the tree. This makes the Indian
pipe a <b>myco-heterotrophic</b> parasite. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Other plants without chloroplasts are <b>holoparasitic </b>(gain nutrients only by parasitism). These would include the rafflesia
species of the Indonesian rainforests. These plants are know for having the
largest single flowers in the world, some the size of car tires! The
plant doesn’t have a stem or root or leaf, it is a vine that grows inside
another type of vine. Only when it is ready to flower does it bud out from the
bark of the host. The flower takes nine moths to develop, and then smells like
rotting flesh in order to attract fly pollinators.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxPlR_DO-BDAKmZaC75tpovqdf27yp7-j5a5ZNfagbn2mHCVKUiSXZXPLr_y_iefSsEQ6frdFG_ihD2kC2aqGLi8Ijg-iZbHuTHM0nmSXlmwrI9aDQfmi9WsYzeS3L_QF6YPKVQ0Q_Kbhv/s1600/2-Rafflesia.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="274" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhxPlR_DO-BDAKmZaC75tpovqdf27yp7-j5a5ZNfagbn2mHCVKUiSXZXPLr_y_iefSsEQ6frdFG_ihD2kC2aqGLi8Ijg-iZbHuTHM0nmSXlmwrI9aDQfmi9WsYzeS3L_QF6YPKVQ0Q_Kbhv/s320/2-Rafflesia.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">Rafflesia is also known as the corpse flower, as
opposed </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">to the corpse plant (Indian pipe). This is because
it </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">smells like a corpse in order to attract the flies
that </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">pollinate it. This young man is either holding his
breath, </span></span></div>
<div class="MsoNormal">
<span class="assemblygist"><span style="font-size: 10pt;">has no sense of smell, or is just really odd.</span></span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">In
addition</span> to holoparasitic plants, plant cells without chloroplasts would
include those same gamete cells we discussed above as not having cell walls.
And neither to do most root cells. However, there are exceptions, like many of
the orchids. The ghost orchid has photosynthetic roots, which is a good idea,
since they grow directly on other plants; their roots are not buried in the
dirt.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Maybe it is not a single characteristic that makes a plant
cell a plant cell, or a plant a plant. Maybe it is the combination of cells
with cell walls, central vacuoles and in most cases, chloroplasts that make it
a plant. I guess it is like beauty; you can’t define it, but you know it when
you see it.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Next week we will take another shot at finding a defining
characteristic of plant cells, namely the plastid, the mother of all chloroplasts
– might there be an exception?</div>
<div class="MsoNormal">
<br /></div>
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=The+Journal+of+cell+biology&rft_id=info%3Apmid%2F5950730&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Centriole+replication.+II.+Sperm+formation+in+the+fern%2C+Marsilea%2C+and+the+cycad%2C+Zamia.&rft.issn=0021-9525&rft.date=1966&rft.volume=29&rft.issue=1&rft.spage=97&rft.epage=111&rft.artnum=&rft.au=Mizukami+I&rft.au=Gall+J&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CReproduction%2C+Botany%2C+Biochemistry%2C+Cell+Biology%2C+Structural+Biology">Mizukami I, & Gall J (1966). Centriole replication. II. Sperm formation in the fern, Marsilea, and the cycad, Zamia. <span style="font-style: italic;">The Journal of cell biology, 29</span> (1), 97-111 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/5950730" rev="review">5950730</a></span>
</div>
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Annals+of+botany&rft_id=info%3Apmid%2F24942001&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Holoparasitic+Rafflesiaceae+possess+the+most+reduced+endophytes+and+yet+give+rise+to+the+world%27s+largest+flowers.&rft.issn=0305-7364&rft.date=2014&rft.volume=114&rft.issue=2&rft.spage=233&rft.epage=42&rft.artnum=&rft.au=Nikolov+LA&rft.au=Tomlinson+PB&rft.au=Manickam+S&rft.au=Endress+PK&rft.au=Kramer+EM&rft.au=Davis+CC&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CAnatomy%2C+Biochemistry%2C+Cell+Biology%2C+Botany%2C+Reproduction%2C+Structural+Biology%2C+Genetics+%2C+Evolutionary+Biology">Nikolov LA, Tomlinson PB, Manickam S, Endress PK, Kramer EM, & Davis CC (2014). Holoparasitic Rafflesiaceae possess the most reduced endophytes and yet give rise to the world's largest flowers. <span style="font-style: italic;">Annals of botany, 114</span> (2), 233-42 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/24942001" rev="review">24942001</a></span>
<br />
<br />
<br />
<div class="MsoNormal">
<span style="font-size: 10pt;">For
more information and classroom activities on cell walls or parasitic plants,
see:</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Cell
walls – </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.biology4kids.com/files/cell_wall.html">http://www.biology4kids.com/files/cell_wall.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.scienceprofonline.com/microbiology/bacterial-cell-wall-structure-gram-positive-negative.html">http://www.scienceprofonline.com/microbiology/bacterial-cell-wall-structure-gram-positive-negative.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://library.thinkquest.org/C004535/cell_wall.html">http://library.thinkquest.org/C004535/cell_wall.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ccrc.uga.edu/~mao/intro/ouline.htm">http://www.ccrc.uga.edu/~mao/intro/ouline.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://micro.magnet.fsu.edu/cells/plants/cellwall.html">http://micro.magnet.fsu.edu/cells/plants/cellwall.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.cellsalive.com/cells/cellwall.htm">http://www.cellsalive.com/cells/cellwall.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/cw.html">http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/cw.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://employees.csbsju.edu/ssaupe/biol327/lecture/cell-wall.htm">http://employees.csbsju.edu/ssaupe/biol327/lecture/cell-wall.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.biologie.uni-hamburg.de/b-online/e26/26.htm">http://www.biologie.uni-hamburg.de/b-online/e26/26.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.answers.com/topic/how-does-a-primary-cell-wall-differ-from-a-secondary-cell-wall">http://www.answers.com/topic/how-does-a-primary-cell-wall-differ-from-a-secondary-cell-wall</a></span></div>
<div class="MsoNormal">
<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.umsl.edu/~microbes/introductiontobacteria.pdf"><span style="font-style: normal;">www.umsl.edu/~microbes/introductionto</span><b><span style="font-style: normal;">bacteria</span></b><span style="font-style: normal;">.pdf</span></a></span></cite></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.scienceprofonline.org/microbiology/gram-negative-bacteria-cell-wall.html">http://www.scienceprofonline.org/microbiology/gram-negative-bacteria-cell-wall.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://tami-port.suite101.com/how-do-antibiotics-work-to-kill-bacteria-a74616">http://tami-port.suite101.com/how-do-antibiotics-work-to-kill-bacteria-a74616</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Parasitic
plants - </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://waynesword.palomar.edu/plnov99.htm">http://waynesword.palomar.edu/plnov99.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.botany.org/parasitic_plants/Hydnora_africana.php">http://www.botany.org/parasitic_plants/Hydnora_africana.php</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.teachervision.fen.com/dk/science/encyclopedia/parasitic-plants.html">http://www.teachervision.fen.com/dk/science/encyclopedia/parasitic-plants.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.bbc.co.uk/learningzone/clips/parasitic-plant/12796.html">http://www.bbc.co.uk/learningzone/clips/parasitic-plant/12796.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.ehow.com/info_8575832_two-rain-forest-illustrate-parasitism.html">http://www.ehow.com/info_8575832_two-rain-forest-illustrate-parasitism.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.moreheadplanetarium.org/index.cfm?fuseaction=page&filename=science360_flowerpower_videouse.html&print=1">http://www.moreheadplanetarium.org/index.cfm?fuseaction=page&filename=science360_flowerpower_videouse.html&print=1</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.montgomeryadvertiser.com/article/20120427/LIFESTYLE/304270006/Parasitic-field-dodder-very-hard-control">http://www.montgomeryadvertiser.com/article/20120427/LIFESTYLE/304270006/Parasitic-field-dodder-very-hard-control</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.parasiticplants.siu.edu/">http://www.parasiticplants.siu.edu/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://parasiticplants.blogspot.com/">http://parasiticplants.blogspot.com/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.apsnet.org/edcenter/intropp/pathogengroups/pages/parasiticplants.aspx">http://www.apsnet.org/edcenter/intropp/pathogengroups/pages/parasiticplants.aspx</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.forestpathology.org/mistle.html">http://www.forestpathology.org/mistle.html</a></span></div>
<span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.gardenbuildingsdirect.co.uk/Article/parasitic-plants">http://www.gardenbuildingsdirect.co.uk/Article/parasitic-plants</a></span>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com9tag:blogger.com,1999:blog-8136765635696545893.post-289446081854154462017-12-07T06:00:00.000-05:002017-12-07T06:00:01.399-05:00Many Paths To The Top Of The Mountain<div class="MsoNormal">
Biology concepts – hydrogenosome, FeS cluster protein, loricifera,
erythrocyte </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYX7y86QxPBQmOkwnpfS6XgMZ3yHe3ohv8_Ebf1B8tZBKYpuGszQk2XP4dikyVpcYXv5japYHlq3tbgFkpb4A6gsQ6ObbA7z5MFruIcK24wJJV9wxJa3QX4hem4OYzKNhB9KmUr9ag2jPN/s1600/skin+a+cat.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="237" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYX7y86QxPBQmOkwnpfS6XgMZ3yHe3ohv8_Ebf1B8tZBKYpuGszQk2XP4dikyVpcYXv5japYHlq3tbgFkpb4A6gsQ6ObbA7z5MFruIcK24wJJV9wxJa3QX4hem4OYzKNhB9KmUr9ag2jPN/s320/skin+a+cat.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><style>
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<br />
<div class="MsoNormal">
<span style="font-size: 10pt;">More
than one way to skin a cat seems to </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">be
a newer version of the old British saying, </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">“there
are more ways to kill a cat than by </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">choking
it with cream.” Mark Twain was one </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">of
the first to use the cat skinning version, in his </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">classic
<i>A Connecticut Yankee in King Arthur’s </i></span></div>
<i><span style="font-family: "cambria"; font-size: 11pt;">Court</span></i><span style="font-family: "cambria"; font-size: 10pt;">.</span>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The old</span>
Chinese proverb says, “There are many paths to the top of the mountain, but the
view is always the same.” Put somewhat less delicately, “There’s more than one
way to skin a cat.” Who wants to skin a cat? I think there is something to be
said for the wisdom gained in 4000 years of culture, to say nothing of the
ability to say it better.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In biology, this is particularly relevant; organisms have
found different ways to do the same things, and different ways to do different
things, but the end goal is always the same – live long enough to reproduce and the more offspring the better.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Last week we talked about how some organisms have degraded
their mitochondria into mitosomes, and how they get along fine just using glycolysis and
fermentation for energy (and maybe some arginine dihydrolase action). But there
is another mitochondrial remnant in some other species of anaerobic eukaryotes
called the <b>hydrogenosome</b>, and it works
more like a mitochondrion than does the <a href="http://biologicalexceptions.blogspot.com/2012/05/biological-energy-crisis.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">mitosome</span></a>. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht6iKlrvjkVx3xEMmFMnWjc8igP3b5cgIRIcQNHAIYfPV_CvN-AaPSU9XDI18mgpUM6HtdpjzGivydWXUbeqPdmG73pG_HQOxr0UazyC3vjxvgwVAmoZLRnrNoZm03DSBs-9CFwOHf8Qnw/s1600/vaginalis+hydrogenosome.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEht6iKlrvjkVx3xEMmFMnWjc8igP3b5cgIRIcQNHAIYfPV_CvN-AaPSU9XDI18mgpUM6HtdpjzGivydWXUbeqPdmG73pG_HQOxr0UazyC3vjxvgwVAmoZLRnrNoZm03DSBs-9CFwOHf8Qnw/s320/vaginalis+hydrogenosome.jpg" width="224" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 10pt;">Here
is the <i>T. vaginalis </i>protist. The blue
probe </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">binds
to DNA (just one nucleus for this guy) and </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">the
yellow probe binds to a hydrogenosome </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">protein.
The strands at the top are the flagella it </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">uses
to move, not its hair.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<br />
<i>Trichonomas vaginalis</i>
is a eukaryotic amitochondriate, and therefore is an <b>anaerobic</b> (without oxygen) protozoan. Unlike many protozoans, <i>T. vaginalis</i> does not have an
environmentally resistant form (something that can live outside the host for a
prolonged time – often called a <b>cyst</b>).
It is transmitted directly from host to host, in this case sexually.
Trichomoniasis is the most common curable sexually transmitted disease, but 70%
of cases have no symptoms (<b>asymptomatic</b>). This is unfortunate because <i>T. vaginalis</i> infection can predispose to
HIV infection and even cervical <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">cancer</span>. Having symptoms initially might prevent some of the later tragedies.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Unlike the mitosome containing protists, <i>T. vaginalis </i>does use its mitochondrial
remnant (<b>hydrogenosome</b>) to make ATP. The hydrogenosome was discovered much earlier than the mitosome,
although they have the same origin and general morphology. Because of this
difference in timing, amitochondrial organisms with hydrogenosomes are called
type II amitochondriates. Type I’s were the organisms that presumably didn’t
have any mitochondrial-like organelle (and were seen first), like the Giardia
and <i>E. histolytica</i> that we now know
have mitosomes.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Pyruvate generated by glycolysis enters the hydrogenosomes
just like it does in mitochondria. The Krebs cycle would be next for
aerobic organisms, but in the hydrogenosome, iron-containing enzymes convert
the pyruvate into an intermediate that has CoA (coenzyme A) bound to it. When
this CoA is removed, energy is released, and this energy is used to convert ADP
to ATP. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Because ATP production occurs at the level of <b>substrate</b> (a molecule
being chemically changed, in this case by an enzyme), it is called <b>substrate
level phosphorylation</b>. This is in contrast to the use of oxygen and the
electron transport chain of proteins to produce ATP through the proton gradient
(<a href="http://biologicalexceptions.blogspot.com/2012/05/biological-energy-crisis.html" style="background-color: white;"><span style="-moz-background-clip: border; -moz-background-origin: padding; -moz-background-size: auto auto; background-attachment: scroll; background-image: none; background-position: 0% 0%; background-repeat: repeat;">oxidative phosphorylation</span></a>).
One of the byproducts of the pathway is hydrogen, hence the name of the
organelle.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
In terms of energy production, the pyruvate:ferredoxin
oxido-reductase (the iron/sulfate-containing enzyme in hydrogenosomes, often
abbreviated as FeS cluster enzymes) pathway is about as efficient as the <a href="http://biologicalexceptions.blogspot.com/2012/05/biological-energy-crisis.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">arginine dihydrolase pathway</span></a>
(ADH) in some mitosome-containing organisms. However, <i>T. vaginalis</i> also contains the ADH pathway, so it comes out ahead
of Giardia in terms of energy production.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
While the hydrogenosome has some activity in energy
production via the FeS-protein mediated metabolism of pyruvate with production
of ATP, the mitosome seems to be limited to the assembly of the FeS clusters
only. A study of the proteins of the mitosome show the parts are there to make
the FeS clusters, but that there are not the enzymes needed to break down
pyruvate and produce ATP.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGp_RmEOnAhePRq8kXlGrL_N_K4CWwVywD4IlyldtZv8v1c6X9r__lj0jvQQmJ4FZtpaf9LHoYln6qE_cm9Ae4DPbXc6GjHKmUIePywxUeWNAH1jdbbuwPCmvc8jRIrHrM592xvQHDA0eg/s1600/cowpack2.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGp_RmEOnAhePRq8kXlGrL_N_K4CWwVywD4IlyldtZv8v1c6X9r__lj0jvQQmJ4FZtpaf9LHoYln6qE_cm9Ae4DPbXc6GjHKmUIePywxUeWNAH1jdbbuwPCmvc8jRIrHrM592xvQHDA0eg/s320/cowpack2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 10pt;">A
study trying to quantify the amount of methane </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">gas
produced by cows was carried out recently </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">in
Argentina. The method involved a big backpack </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">and
a delicately placed rubber hose. At some point, </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">scientist A approached scientist B and said, I’ve </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">got
a great idea….”</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Other
hydrogenosome</span>-containing organisms include the anaerobic unicellular
fungus, <i>Neocallimastix frontalis</i> (it
lives in the guts of rumen animals like cows). <i>N. frontalis</i> byproducts are used by gut methanogens
(methane-producing bacteria) and therefore contributes to the generous amount
of gas produced by cows. Many estimates name dairy and beef cattle flatulence
as a bigger source of greenhouse gases than automobiles!</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Another hydrogenosome-containing protozoan is <i>Nyctotherus ovalis</i>. It lives in the GI
tract of cockroaches, and efficiently works with an archaeal bacterium that
uses the hydrogen that the hydrogenosomes release. Just one more reason that
cockroaches will outlast us all. The fact that some fungi and some protozoans
have hydrogenosomes indicates that this organelle has evolved independently
from mitochondria at least three different times in history – they must be a
good idea.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Even with the exception of anaerobic protists and fungi, it
was believed until just recently that at least all multicellular eukaryotic (<b>metazoan</b>) organisms depended aerobic respiration
for energy production. However, there are even metazoan exceptions. A <a href="http://www.biomedcentral.com/1741-7007/8/30">2010 study</a> of the
bottom of the Mediterranean Sea found three different animals that survive
without using oxygen and therefore don’t have mitochondria. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The deepest basin of the Med, near Greece, is nearly anoxic (an
environment without oxygen). In
the muds of this basin were found three <b>loriciferan</b>
(lorici = corsette and fera = bearing, so organisms with a sort of girdle)
species that live in this area all the time. Other animals can survive in an
anoxic environment for a while, but they don’t call it home.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6BqSoRRwnIZld_yhS0MUlnNw-Ndh0Gi0EHGnI8clnB2l9FNkgRMffJOQiDdVrbZOqhNFh8ylkZv2zpKWPGsYh73TxYpSgAsHPey06xdLhs9u6YG6nJ5FVZwQGwz10MPqyeB1y6ZLeyZMd/s1600/loriciferan.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6BqSoRRwnIZld_yhS0MUlnNw-Ndh0Gi0EHGnI8clnB2l9FNkgRMffJOQiDdVrbZOqhNFh8ylkZv2zpKWPGsYh73TxYpSgAsHPey06xdLhs9u6YG6nJ5FVZwQGwz10MPqyeB1y6ZLeyZMd/s1600/loriciferan.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 10pt;">Loriciferans
weren’t even discovered until 1983. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Now
we have some that live as anaerobes. Most </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">species
of this phylum live in the deep waters, </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">but
only a few are obligate anaerobes, meaning </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">they
can only perform anaerobic respiration. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Oxygen
can be damaging, it likes to scavenge </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">electrons, I wonder if it is toxic to the loriciferans.</span>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">These new
loricife</span>rans have hydrogenosomes instead of mitochondria, and produce
ATP in the same ways as <i>T. vaginalis</i>
and the other anaerobic eukaryotes. This is a completely new door being opened
in biology, because the multicellular animals evolved after Earth turned from
an anoxic environment to a place where oxygen was plentiful. It seems that even some
of the more advanced organisms don’t have a problem reverting to more ancient
systems if they find themselves in a place where they need it.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Would you believe that some of your cells might not have
mitochondria? Well, about 26 trillion of your cells (if you’re an adult male)
are amitochondrial – your red blood cells. That’s right; the erythrocytes that
deliver oxygen to your cells in order so they can make ATP in their
mitochondria don’t have any mitochondria of their own! In an attempt to carry
as much oxygen as possible (bound to a big molecule called <b>hemoglobin</b>) your red
blood cells have evicted their mitochondria. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
This is probably a good idea, since making energy in the
erythrocytes would use up the oxygen they are supposed to deliver to
other cells. Instead, they act more like prokaryotes, and carry out glycolysis
and lactic acid fermentation in their cytoplasm for the energy they need. To
gain more room for hemoglobin, the RBCs have also done away with their
nucleus. They have no way to
produce more proteins or repair themselves, so they work as long as they can
and then they are replaced. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Old erythrocytes are phagocytosed (eaten) by macrophages in
the spleen and liver and are destroyed. New RBCs (about 2 million per second)
are produced in your bone marrow. The spleen also acts as a reservoir for blood
cells, a ready supply for when you need them, but you can get along without it,
you are just more susceptible to infections, since the spleen houses many white
blood cells just waiting to recognize a pathogen that needs to be taught a
lesson.</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGQzkX5aepL5lrJ4ZxJqiyYm8LY3utZ3aPiyJ39pQqC6Ufv-LjybPS-TRBgDgOkOgiW3lktODLJcyxCGuhKR-zLHkgFq7GwJh3WMvnNGBOQL-hsKq4RyN3Z5UBb4FbuGiSdjrVceJu8n27/s1600/blood+cells.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="154" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGQzkX5aepL5lrJ4ZxJqiyYm8LY3utZ3aPiyJ39pQqC6Ufv-LjybPS-TRBgDgOkOgiW3lktODLJcyxCGuhKR-zLHkgFq7GwJh3WMvnNGBOQL-hsKq4RyN3Z5UBb4FbuGiSdjrVceJu8n27/s320/blood+cells.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 10pt;">Human
red blood cells (left) are round and biconcave, </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">but
the camel RBCs are oval. You can see why so many </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">people
believe they have a nucleus, but what you are seeing </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">is
their biconcave side staining darker. The large cell in the </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">middle is an immune cell.</span>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><b>A</b><b>nucleate</b> (a = without, and nucleate = pertaining to a nucleus) erythrocytes</span> are the norm for mammals. Many people think that
camels are the exception, that they have nucleated RBCs, but this is not so.
But they do have ovoid RBCs. When they run low on water, camels can remove
water from their blood and use it in their cells. This leaves their blood
thicker and harder to push through the small capillaries. Round RBCs would be
impossible to squeeze through when the blood is viscous, so the camel has
evolved RBCs that are longer in one direction and smaller in the other, to help
blood flow in times of dehydration.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
On the other hand, almost all non-mammalian vertebrates do
have erythrocytes that do have nuclei. The only exceptions are a few salamander species
that have some anucleate erythrocytes. For example, 95% of the <i>Batrachoseps attenuatus</i> salamander’s RBCs
are anucleate. There is also the pearlside fish which is known to have
non-nucleated red blood cells.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
However, the crocodile icefish is even a bigger exception;
it is the only vertebrate animal that has gotten rid of its RBCs altogether.
This species lives in cold, highly oxygenated waters. The oxygen it needs just travels
in the blood as a dissolved gas and is carried to every cell. These fish have even
lost the DNA for making hemoglobin – now that is efficiency!</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKsg4VAz8HVaIwXkfHHjs5R_lN5zoLtxJpXp3meIm8wYGa_twGP7zpqe1kDrOi8EnKPAclKTxYbaY5Dzj5b2PoxKMhTiAYGrW2tjU-j8LxaiollggxZxHaYsQXBqC1Y6Of46__9fQI-CQT/s1600/number+of+genes.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="233" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKsg4VAz8HVaIwXkfHHjs5R_lN5zoLtxJpXp3meIm8wYGa_twGP7zpqe1kDrOi8EnKPAclKTxYbaY5Dzj5b2PoxKMhTiAYGrW2tjU-j8LxaiollggxZxHaYsQXBqC1Y6Of46__9fQI-CQT/s320/number+of+genes.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 10pt;">Given
our apparent complexity, it is amazing </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">just
how few genes humans have; the grape </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">has almost 30% more. The chicken doesn’t have </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">many fewer than us,
and we don’t have to worry </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">about laying
eggs. What is more amazing is that nine </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">years
after the completion of the human genome </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">project,
we still aren't exactly sure how many </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">genes we
have.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Or is it?</span>
We have recently discovered that the majority of proteins have more than one
function. Scientists gave this idea more thought when the results of the human
genome project started to role in and we discovered far fewer genes than we
expected. It is now accepted that humans have about 22,000 genes, not even as
many as the grape, which has 31,000. Even the lowly fruit fly has 15,000 genes!
How do we get so many functions out of so few gene products? Multitasking! </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Take hemoglobin for example, it doesn’t just carry oxygen in
the blood. It also acts as an antioxidant in several types of immune cells, and
in certain neurons. It is a regulator of iron uptake and metabolism,
since it carries iron at its core. It destroys nitric oxide, which is one
reason why the little blue pill doesn’t work forever. You have to wonder what
else the crocodile icefish has lost by giving up its hemoglobin and how it has
made up for these losses. One change probably requires many more to be made as well.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
We have seen how some organisms get along without
mitochondria. What about the other end of the energy equation? Plants can make
their own carbohydrate in the chloroplast – but is that what makes it a plant?
Let’s look at this next time.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=BMC+Biology&rft_id=info%3Adoi%2F10.1186%2F1741-7007-8-30&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=The+first+metazoa+living+in+permanently+anoxic+conditions.&rft.issn=&rft.date=2010&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Roberto+Danovaro%2C+Antonio+Dell%27Anno1%2C+Antonio+Pusceddu%2C+Cristina+Gambi1%2C+Iben+Heiner+and+Reinhardt+M%C3%B8bjerg&rft.au=Kristensen&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Evolutionary+Biology%2C+Cell+Biology%2C+Biochemistry%2C+Structural+Biology">Roberto Danovaro, Antonio Dell'Anno1, Antonio Pusceddu, Cristina Gambi1, Iben Heiner and Reinhardt Møbjerg, & Kristensen (2010). The first metazoa living in permanently anoxic conditions. <span style="font-style: italic;">BMC Biology</span> DOI: <a href="http://dx.doi.org/10.1186/1741-7007-8-30" rev="review">10.1186/1741-7007-8-30</a></span>
<br />
<div class="MsoNormal">
<br /></div>
<span style="font-size: 10pt;">For
more information or classroom activities on hydrogenosome, FeS cluster protein,
loricifera, erythrocyte, see:</span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Hydrogenosome
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://dna.kdna.ucla.edu/parasite_course-old/trichomonas/subchapters/hydrogenosome.htm">http://dna.kdna.ucla.edu/parasite_course-old/trichomonas/subchapters/hydrogenosome.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://web.natur.cuni.cz/~parazit/tachezy_web/hydrogenosome.htm">http://web.natur.cuni.cz/~parazit/tachezy_web/hydrogenosome.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.wired.com/wiredscience/tag/hydrogenosome/">http://www.wired.com/wiredscience/tag/hydrogenosome/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.talkingscience.org/2010/12/the-hydrogenosome-an-anaerobic-powerhouse/">http://www.talkingscience.org/2010/12/the-hydrogenosome-an-anaerobic-powerhouse/</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">FeS
cluster protein – </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://udel.edu/~forbescr/General_Iron_Sulfur_Reactions.htm">http://udel.edu/~forbescr/General_Iron_Sulfur_Reactions.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.trinity.edu/lhunsick/ironsulfur_cluster_proteins.htm">http://www.trinity.edu/lhunsick/ironsulfur_cluster_proteins.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.biochem.wisc.edu/faculty/craig/lab/iron.aspx">http://www.biochem.wisc.edu/faculty/craig/lab/iron.aspx</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://ghr.nlm.nih.gov/condition/myopathy-with-deficiency-of-iron-sulfur-cluster-assembly-enzyme">http://ghr.nlm.nih.gov/condition/myopathy-with-deficiency-of-iron-sulfur-cluster-assembly-enzyme</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://guweb2.gonzaga.edu/faculty/cronk/biochem/I-index.cfm?definition=iron-sulfur">http://guweb2.gonzaga.edu/faculty/cronk/biochem/I-index.cfm?definition=iron-sulfur</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.impactaging.com/papers/v2/n11/full/100238.html">http://www.impactaging.com/papers/v2/n11/full/100238.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www-ssrl.slac.stanford.edu/research/iron-sulfur_clusters_summary.html">http://www-ssrl.slac.stanford.edu/research/iron-sulfur_clusters_summary.html</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Loricifera
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://icb.oxfordjournals.org/content/42/3/641.full">http://icb.oxfordjournals.org/content/42/3/641.full</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://scitechstory.com/2010/04/07/loricifera-larger-life-without-oxygen/">http://scitechstory.com/2010/04/07/loricifera-larger-life-without-oxygen/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.earthlife.net/inverts/loricifera.html">http://www.earthlife.net/inverts/loricifera.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.nature.com/news/2010/100406/full/464825b.html">http://www.nature.com/news/2010/100406/full/464825b.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://comenius.susqu.edu/biol/202/animals/protostomes/ecdysozoa/loricifera/default.htm">http://comenius.susqu.edu/biol/202/animals/protostomes/ecdysozoa/loricifera/default.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://schaechter.asmblog.org/schaechter/2010/04/true-or-false-all-metazoans-need-o2.html">http://schaechter.asmblog.org/schaechter/2010/04/true-or-false-all-metazoans-need-o2.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://accessscience.com/content/Loricifera/757448">http://accessscience.com/content/Loricifera/757448</a></span></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Erythrocytes
– </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.thirteen.org/edonline/lessons/redgold/b.html">http://www.thirteen.org/edonline/lessons/redgold/b.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/nova/teachers/activities/0305_03_nsn.html">http://www.pbs.org/wgbh/nova/teachers/activities/0305_03_nsn.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://alex.state.al.us/lesson_view.php?id=23816">http://alex.state.al.us/lesson_view.php?id=23816</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_human/cub_human_lesson05_activity1.xml">http://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_human/cub_human_lesson05_activity1.xml</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.wisc-online.com/objects/ViewObject.aspx?ID=ap14604">http://www.wisc-online.com/objects/ViewObject.aspx?ID=ap14604</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://library.thinkquest.org/3564/lessons/lesson3/lesson3.html">http://library.thinkquest.org/3564/lessons/lesson3/lesson3.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://teachhealthk-12.uthscsa.edu/curriculum/blood/blood03.asp">http://teachhealthk-12.uthscsa.edu/curriculum/blood/blood03.asp</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://education-portal.com/academy/lesson/circulatory-system-iv-red-blood-cells.html">http://education-portal.com/academy/lesson/circulatory-system-iv-red-blood-cells.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.lessoncorner.com/Science/Biology/Cardiovascular_System/Blood_Cells">http://www.lessoncorner.com/Science/Biology/Cardiovascular_System/Blood_Cells</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.funsci.com/fun3_en/blood/blood.htm">http://www.funsci.com/fun3_en/blood/blood.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://faculty.ucc.edu/biology-potter/life_cycle_of_the_erythrocyte.htm">http://faculty.ucc.edu/biology-potter/life_cycle_of_the_erythrocyte.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.fi.edu/learn/heart/blood/red.html">http://www.fi.edu/learn/heart/blood/red.html</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://faculty.stcc.edu/AandP/AP/AP2pages/Units18to20/blood/redblood.htm">http://faculty.stcc.edu/AandP/AP/AP2pages/Units18to20/blood/redblood.htm</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com5tag:blogger.com,1999:blog-8136765635696545893.post-47167453828324145272017-11-30T06:00:00.000-05:002017-11-30T06:00:05.463-05:00A Biological Energy Crisis<div class="MsoNormal">
Biology concepts – mitochondria, aerobic respiration, anaerobic respiration, glycolysis, fermentation, mitosome</div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPt7ndnMfW1AYaU6luQnnCXQFvSQZcHH3FJA70K9sOiFKgPlaEwO2kenjjMjciuWGNLfDx2eE1sy4jV51UDlo5dTjAN4fn3iUvkotbDxJeUE8AgBf9xWHHXGKtyLDu9T6Kfw_sUIbx1EFB/s1600/bee+hummingbird.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="243" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPt7ndnMfW1AYaU6luQnnCXQFvSQZcHH3FJA70K9sOiFKgPlaEwO2kenjjMjciuWGNLfDx2eE1sy4jV51UDlo5dTjAN4fn3iUvkotbDxJeUE8AgBf9xWHHXGKtyLDu9T6Kfw_sUIbx1EFB/s320/bee+hummingbird.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><style>
@font-face {
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<div class="MsoNormal">
<span style="font-size: 10pt;">The bee hummingbird is the smallest bird in the world. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Living on the 2 largest islands of Cuba, this little </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">guy is only 5 cm (1.9 in) long and weighs just a bit more </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">than a paperclip. The males and females live in separate </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">nests and never see each other again after mating.</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Birds</span> in flight use an astounding amount of energy, and the smallest birds use the most energy. Hovering hummingbirds must flap their wings 50-80 times a second, which requires a lot of energy. To meet this demand, they use 10x the amount of oxygen that a person uses (per gram of body weight)! To move this much oxygen in their blood when flying, their hearts must beat over 1200 times per minute. At that rate, a red blood cell can traverse the bird’s entire circulatory system in less than one second!</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
It is a vicious circle; the hummingbird must eat constantly in order to have the energy to hover, and it must hover in order to eat constantly. Hummingbirds convert their carbohydrate intake into cellular energy (<b>ATP</b>) on the fly, using the sugars ingested only a few minutes earlier to support up to 90% of their need. Contrast that to humans; elite athletes can draw only about 15% of their needed energy from the sugars they ate recently. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
So how is all this energy made? Since we have been talking about the mitochondria on and off for several weeks, you would be right to guess that this organelle is involved, but it doesn’t start there. </div>
<div class="MsoNormal">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPg6w46NULj4cFChubRgcg55JAYt5ZEFv6DeE8ALlwXxhNHFBYONM1zCp-DTBZ8LeCHJh_mWeGgIVDOt0hS-RzwFPgnEmrnAkHj4Hkreoq-PpxF3qPWCfsVFRzaPPuof4-2mU-U44Y51eT/s1600/glycolysis.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="196" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhPg6w46NULj4cFChubRgcg55JAYt5ZEFv6DeE8ALlwXxhNHFBYONM1zCp-DTBZ8LeCHJh_mWeGgIVDOt0hS-RzwFPgnEmrnAkHj4Hkreoq-PpxF3qPWCfsVFRzaPPuof4-2mU-U44Y51eT/s320/glycolysis.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">br />
<br />
<div class="MsoNormal">
<span style="font-size: 10pt;">This is an extremely simple cartoon of glycolysis.</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">If you want more detail, like which step calls for </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">glyceraldehyde phosphate dehydrogenase, then </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">look <a href="http://www.johnkyrk.com/glycolysis.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">here</span></a>.</span> </td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Dietary</span> glucose ends up in the cytoplasm after it is eaten and transported through the blood to each and every cell in the body. In the cytoplasm, the sugar is broken down in a process called <b>glycolysis</b> (gly = glucose and lysis = splitting). This process takes the carbohydrate from a six-carbon sugar down to two three-carbon sugars (pyruvate). In the process, there is a net gain of two ATP molecules (four are actually made per glucose but you have to invest 2 ATPs to get the process rolling). That isn’t much of a payoff. There must be something more, and this is where the mitochondria figure in the process.</div>
<div class="MsoNormal">
<br /></div>
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The pyruvates are taken into the mitochondria and a second process begins to consume them. First there is a carbon and two oxygens removed from each pyruvate to form acetyl-CoA in what is called a <b>linking reaction</b>, since it links glycolysis to the next step - the <b>citric acid cycle</b> (Kreb’s cycle). In this cycle, a series of reactions takes place to sequentially remove carbons from the sugar, leaving a four-carbon molecule (oxaloacetate) that then joins to the acetyl-CoA produced from another pyruvate. The series of reactions results in 2 ATPs and 6 NADH’s formed. This latter molecule (long name = <b>n</b>icotinomide <b>a</b>denine <b>d</b>inucleotide + <b>h</b>ydrogen) will become important in the final step. </div>
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Remember that the mitochondrion has two membranes, and the inner membrane is folded into many <b>cristae</b>, in order to increase its surface area. The NADH’s produced during the Krebs cycle work with a series of proteins embedded in the inner mitochondrial membrane (called the <b>electron transport chain</b>) to create a proton gradient. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjfaLNRsqgMQFFOmOkROezinH_HKwimh0tJt3gT5jyGYOmqy_n2HACwhO25J2OljLmfjX0lu5juZy-cr90G9DXErEjNY_j1FMa6SaW6I8eB7KhCandSgPbmoqtPVRMC4kWM7Z0IhYa7u2s/s1600/electron+transport.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="245" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjfaLNRsqgMQFFOmOkROezinH_HKwimh0tJt3gT5jyGYOmqy_n2HACwhO25J2OljLmfjX0lu5juZy-cr90G9DXErEjNY_j1FMa6SaW6I8eB7KhCandSgPbmoqtPVRMC4kWM7Z0IhYa7u2s/s400/electron+transport.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="font-size: 10pt;">This is a Goldilocks version of the electron transport chain; the level </span></div>
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<span style="font-size: 10pt;">of detail is juust right. Keep an eye out for the NADH, the water, and </span></div>
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<span style="font-size: 10pt;">the protons moving in and out. They are important, as is the flow of </span></div>
<span style="font-size: 10pt;">the </span><span style="font-family: "cambria"; font-size: 10pt;">electron, hence the name; the electron transport chain.</span> </td></tr>
</tbody></table>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">When the</span> NADH is broken down, a hydrogen ion (the same thing as a proton) is pushed into the inner membrane space. This is against its gradient and creates a high-energy situation, since it wants to move back into the matrix (the space inside the inner membrane). The ATP synthase allows the proton to move back in, but uses the energy of the gradient to convert ADP into ATP<b>.</b> One ATP is made for every proton that is pushed out and then allowed back into the matrix by <b>oxidative phosphorylation</b>. </div>
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The driving force behind NADH’s release of an electron and a proton (hydrogen atom) is that some atom must be waiting to scoop the extra electron, and this something is oxygen (this is why it is called <u>oxidative</u> phophorylation). This is why we have to breathe, the oxygen is a big magnet (metaphorically speaking) for the electron. The oxygen plus the electron plus two hydrogens bind together to form water. This is the metabolic water that is so important to many <a href="http://biologicalexceptions.blogspot.com/2012/01/sorry-i-dont-drink.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">animals that don’t drink water</span></a>. </div>
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All told, the electron transport chain produces 36 ATP molecules per glucose, much more than the paltry 2 resulting from glycolysis (called <b>substrate level phosphorylation</b> as opposed to oxidative phosphorylation). It is a good thing that hummingbirds have mitochondria to wring so much energy out of their food (not so bad for us either). </div>
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And herein lies the exception, some eukaryotes have decided to try to live without mitochondria. It isn’t as though they just never underwent endosymbiosis; recent evidence is showing us that all eukaryotes had mitochondria at some point in their evolution. These exceptional organisms just worked out another way to produce energy, and allowed their mitochondria to disappear or change over time. </div>
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<br />
The human gut pathogen <i>Giardia</i> <i>intestinalis </i>(or <i>lamblia</i>) is a good example. Look as long as you like, but you won’t find a mitochondrion in this protozoan. Until 2003, scientists hypothesized that the lack of mitochondria in <i>G. lamblia</i> meant that it was a very early eukaryote, diverging from other eukaryotes before the <a href="http://biologicalexceptions.blogspot.com/2012/04/evolution-of-cooperation.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">endosymbiotic event</span></a> that created mitochondria. But, then we discovered it was an even bigger exception. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgBut0mCm3LAE559jdPPVOHorXoZ5HLeGyDVHZjnagzHoRo5ZgyXmSjXtPG0NDayGOUCZ-p1Nw5s_bGmSDgVejBw9m8FFOJkfwMIW6I8buQ3Cnh1fB-uThyphenhyphen5MmwXkf5Lt6FksZjXCXFOPL/s1600/giardia.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgBut0mCm3LAE559jdPPVOHorXoZ5HLeGyDVHZjnagzHoRo5ZgyXmSjXtPG0NDayGOUCZ-p1Nw5s_bGmSDgVejBw9m8FFOJkfwMIW6I8buQ3Cnh1fB-uThyphenhyphen5MmwXkf5Lt6FksZjXCXFOPL/s1600/giardia.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="font-size: 10pt;">Meet <i>Giardia intestinalis</i>; he looks happy to see you.</span></div>
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<span style="font-size: 10pt;">The blue probe binds to DNA, those are the two nuclei.</span></div>
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<span style="font-size: 10pt;">The green probe binds to the mitosomes. Just like the</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">duck in A Christmas Story – “it’s smiling at us!”</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Instead</span> of mitochondria, Giardia has 2-50 <b>cryptons</b>, also called <b>mitosomes</b>. These are mitochondrial remnant organelles (crypton = cryptic mitochondrion), with no genome of their own. They are completely reduced; all of their DNA has been transferred to the nucleus or lost, so mitosomes do not replicate on their own. </div>
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In Giardia, the mitosomes line up and down the sides of the organism’s two nuclei, with some between the nuclei. Yes, you're right - Giardia doesn’t have any mitcohondria, but it has two nuclei – go figure. This specific and repeated arrangement suggests a specific function for these organellar remants. We aren’t sure what the functions might be, but it is not energy production. <i>G. intestinalis</i> produces its energy by glycolysis and by <b>fermentation</b> – the same process that yeast use to produce alcohol. </div>
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In alcohol fermentation of yeast, the 3-carbon pyruvates from glycolysis are converted to 2-carbon ethanol and some NADH is converted back to NAD+. This prevents a critical shortage of NAD+ in the cell. The amount of NAD+ in the cell is limited, so if glycolysis is to continue there must be NAD+ must be recycled from NADH. The conversion of NADH back to NAD+ is the main purpose behind fermentation; it doesn’t produce any more energy than glycolysis alone.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKCkpc7sydHJ9c9UBRJyLBKs_K53aMCcrqH42zOVXY9hEWTldWBh4u18atD7DoTbmq3fbZTIeqz01khT6A33njXa_5hGjjGyxiZc-fDLWIuhyphenhyphentoQB4pXOQjkt4ZFUnl7xILrbIQCwrPqCM/s1600/better+ferment.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKCkpc7sydHJ9c9UBRJyLBKs_K53aMCcrqH42zOVXY9hEWTldWBh4u18atD7DoTbmq3fbZTIeqz01khT6A33njXa_5hGjjGyxiZc-fDLWIuhyphenhyphentoQB4pXOQjkt4ZFUnl7xILrbIQCwrPqCM/s400/better+ferment.jpg" width="253" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="font-size: 10pt;">Notice how fermentation doesn’t make more</span></div>
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<span style="font-size: 10pt;">ATP than glycolyis alone. In both lactic acid </span></div>
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<span style="font-size: 10pt;">fermentation and alcohol fermentation change</span></div>
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<span style="font-size: 10pt;">NADH to NAD+. This is the purpose behind </span></div>
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<span style="font-size: 10pt;">fermentation. Lots of energy is left on the </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">table -you can power a car engine on ethanol.</span> </td></tr>
</tbody></table>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">By the way</span> - you ferment too. Yes, you. When oxygen is scarce, mammals will resort to fermentation, we just don’t produce alcohol. Instead, our waste product is lactic acid. In 1929, Nobel laureate Archibald Hill stated that it was the buildup of lactic acid in the muscles that caused muscle soreness after exercise, but his experiment was flawed. It wasn’t until just a few years ago that we discovered that lactic acid is crucial in keeping the muscles working (and brain) working when they are taxed. Lactic acid isn’t the problem, it is part of the solution.</div>
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<br /></div>
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But back to Giardia. Unlike yeast, <i>G. lamblia</i> doesn’t have a choice, it undergoes alcohol fermentation all the time. Make that <u>almost</u> all the time. Without oxygen (even though it doesn’t use it to make ATP) most of the pyruvate is converted to alanine, an amino acid, during fermentation. With even a little bit of oxygen, this switches over to alcohol production. But there is another way Giardia can make some energy.</div>
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A mechanism called the <b>arginine dihydrolase pathway</b> has been seen only in prokaryotes and two eukaryotic anaerobes (Giardia and <i>Trichomonas vaginalis</i>). This speaks to the primitive nature of Giardia; no wonder scientists thought that it didn’t ever have mitochondria, like prokaryotes. In the arginine dihydrolase pathway, a whole bunch of steps lead to a little bit of ATP formation. It must make a difference for the organism’s survival, otherwise they wouldn't invest the energy in maintaining the pathway.</div>
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Giardia isn’t the only eukaryote to choose mitosomes over mitochondria. <i>Entamoeba histolytica</i> also causes diarrhea when it takes up residence in your gastrointestinal tract. I think this suggests that we are providing them with all the carbohydrates they need so that glycolysis and fermentation pay off. Was there less diarrhea before twinkies and french fires? Could be – there is probably grant money available for that study.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVuqMXr4wgy1oFRWJac5humxduJOgvOIw3AgJcp1hQQxY2DwDHSqz8fxxCVJJ5hSoV72G21ijf6uja_rh7J2cQQfq7cBSKztERTgSVQumrMK_Go2Bf59kMHdNrrpOPZFJwVI59Jlh49TXG/s1600/histolytica.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVuqMXr4wgy1oFRWJac5humxduJOgvOIw3AgJcp1hQQxY2DwDHSqz8fxxCVJJ5hSoV72G21ijf6uja_rh7J2cQQfq7cBSKztERTgSVQumrMK_Go2Bf59kMHdNrrpOPZFJwVI59Jlh49TXG/s320/histolytica.JPG" width="274" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<i><span style="font-size: 10pt;">Entamoeba histolytica</span></i><span style="font-size: 11pt;"> and <i>Giardia intestinalis </i></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">are not closely related, they are very different </span></div>
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<span style="font-size: 10pt;">types of protozoa. For instance, <i>Giardia</i> is a </span></div>
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<span style="font-size: 10pt;">flagellete (moves by flagella), but <i>E. histolytica</i> </span></div>
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<span style="font-size: 10pt;">is an amoeboid (moves by body movement). </span></div>
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<span style="font-size: 10pt;">But they both cause diarrhea, and Giardia has </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">two nuclei and <i>E. histolytica</i> has four!</span> </td></tr>
</tbody></table>
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<i style="background-color: white;"><span style="-moz-background-clip: border; -moz-background-origin: padding; -moz-background-size: auto auto; background-attachment: scroll; background-image: none; background-position: 0% 0%; background-repeat: repeat;">E. histolytica</span></i> was also thought to be an ancient eukaryote that never had a mitochondrion, but mitosomes were discovered in this pathogen way back in 1999; the good old days. Another pathogen, <i>Cryptosporidium parvum</i> is also a mitosome-containing amitochondriate. Again, this is an intestinal parasite that causes diarrhea. I think that living in the gut must have turned these organisms into mutants, like the 1950’s animals exposed to radiation in great old movies like Them! and Godzilla.</div>
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<i>C. parvum</i> is closely related to the organism that causes malaria (<i>Plasmodium falciparum</i>), but they make ATP in different ways. <i>P. falciparum </i> has mitochondria and can carry out oxidative phosphorylation via the electron transport chain. So how can they be related? </div>
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Here’s how: <i>P. falciparum </i>might have mitochondria, but they look like they are on their way out. They only have a few genes, and at least one principal enzyme is completely missing. In one stage of the infection, Plasmodium survives only by fermentation (although it goes to lactate, not alcohol), so maybe these two parasites are not so different after all. They have another similarity, but we will talk about that in a couple of weeks when we discuss plants without chloroplasts.</div>
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<span style="font-family: "cambria"; font-size: 12pt;">Fermentation is one way eukaryotic organisms get along without mitochondria, but there are many paths to the top of the mountain. Next time we will look at organisms that found another path.</span><br />
<br />
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Biochimie&rft_id=info%3Apmid%2F24316280&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Highly+divergent+mitochondrion-related+organelles+in+anaerobic+parasitic+protozoa.&rft.issn=0300-9084&rft.date=2014&rft.volume=100&rft.issue=&rft.spage=3&rft.epage=17&rft.artnum=&rft.au=Makiuchi+T&rft.au=Nozaki+T&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CEvolutionary+Biology%2C+Microbiology+%2C+Biochemistry%2C+Cell+Biology%2C+Genetics+%2C+Reproduction%2C+Structural+Biology">Makiuchi T, & Nozaki T (2014). Highly divergent mitochondrion-related organelles in anaerobic parasitic protozoa. <span style="font-style: italic;">Biochimie, 100</span>, 3-17 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/24316280" rev="review">24316280</a></span>
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Gene&rft_id=info%3Apmid%2F24321693&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Differential+gene+expression+in+Giardia+lamblia+under+oxidative+stress%3A+significance+in+eukaryotic+evolution.&rft.issn=0378-1119&rft.date=2014&rft.volume=535&rft.issue=2&rft.spage=131&rft.epage=9&rft.artnum=&rft.au=Raj+D&rft.au=Ghosh+E&rft.au=Mukherjee+AK&rft.au=Nozaki+T&rft.au=Ganguly+S&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Molecular+Biology%2C+Evolutionary+Biology%2C+Genetics+%2C+Biochemistry%2C+Cell+Biology%2C+Chemical+Biology">Raj D, Ghosh E, Mukherjee AK, Nozaki T, & Ganguly S (2014). Differential gene expression in Giardia lamblia under oxidative stress: significance in eukaryotic evolution. <span style="font-style: italic;">Gene, 535</span> (2), 131-9 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/24321693" rev="review">24321693</a></span>
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<span style="font-size: 10pt;">For more information or classroom activities on glycolysis, oxidative phosphorylation, or fermentation, see:</span></div>
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<span style="font-size: 10pt;">Glycolysis – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.nclark.net/PhotoRespiration">http://www.nclark.net/PhotoRespiration</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ehow.com/how_5552502_teach-glycolysis-children.html">http://www.ehow.com/how_5552502_teach-glycolysis-children.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://findarticles.com/p/articles/mi_6958/is_3_70/ai_n28524398/">http://findarticles.com/p/articles/mi_6958/is_3_70/ai_n28524398/</a></span></div>
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<span style="font-size: 10pt;"><a href="https://www.bio.cmu.edu/courses/03231/LecF04/Lec29/lec29.html">https://www.bio.cmu.edu/courses/03231/LecF04/Lec29/lec29.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://resources.educ.queensu.ca/science/main/concept/biol/b02/B02LACG5.htm">http://resources.educ.queensu.ca/science/main/concept/biol/b02/B02LACG5.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.science.smith.edu/departments/Biology/Bio231/">http://www.science.smith.edu/departments/Biology/Bio231/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://biology.about.com/od/cellularprocesses/a/aa082704a.htm">http://biology.about.com/od/cellularprocesses/a/aa082704a.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://biology.clc.uc.edu/fankhauser/Labs/Cell_Biology/glycolysis/Glycolysis.htm">http://biology.clc.uc.edu/fankhauser/Labs/Cell_Biology/glycolysis/Glycolysis.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html">http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.johnkyrk.com/glycolysis.html">http://www.johnkyrk.com/glycolysis.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/glycolysis.htm">http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/glycolysis.htm</a></span></div>
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<br /></div>
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<span style="font-size: 10pt;">oxidative phosphorylation – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.woodrow.org/teachers/bi/1998/presentations/huffman/">http://www.woodrow.org/teachers/bi/1998/presentations/huffman/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch08expl.htm">http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch08expl.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellularRespiration.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellularRespiration.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.qcc.cuny.edu/BiologicalSciences/Faculty/DMeyer/respiration.html">http://www.qcc.cuny.edu/BiologicalSciences/Faculty/DMeyer/respiration.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://staff.jccc.net/pdecell/cellresp/respoverview.html">http://staff.jccc.net/pdecell/cellresp/respoverview.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://resources.educ.queensu.ca/science/main/concept/biol/b02/B02LACG5.htm">http://resources.educ.queensu.ca/science/main/concept/biol/b02/B02LACG5.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=se8apr_qDqE">http://www.youtube.com/watch?v=se8apr_qDqE</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.phschool.com/science/biology_place/labbench/lab5/intro.html">http://www.phschool.com/science/biology_place/labbench/lab5/intro.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.youtube.com/watch?v=eizHVQfeMwo">http://www.youtube.com/watch?v=eizHVQfeMwo</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.wiley.com/legacy/college/boyer/0470003790/animations/electron_transport/electron_transport.htm">http://www.wiley.com/legacy/college/boyer/0470003790/animations/electron_transport/electron_transport.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.chem.purdue.edu/courses/chm333/oxidative_phosphorylation.swf">http://www.chem.purdue.edu/courses/chm333/oxidative_phosphorylation.swf</a></span></div>
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<span style="font-size: 10pt;"><a href="http://student.ccbcmd.edu/~gkaiser/biotutorials/energy/oxphos.html">http://student.ccbcmd.edu/~gkaiser/biotutorials/energy/oxphos.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.phschool.com/science/biology_place/biocoach/cellresp/intro.html">http://www.phschool.com/science/biology_place/biocoach/cellresp/intro.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.scienceprofonline.org/metabolism/electron-transport-chain-classroom-activity.html">http://www.scienceprofonline.org/metabolism/electron-transport-chain-classroom-activity.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.sci.uidaho.edu/bionet/biol115/t4_energy/flash/etc.htm">http://www.sci.uidaho.edu/bionet/biol115/t4_energy/flash/etc.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=xbJ0nbzt5Kw">http://www.youtube.com/watch?v=xbJ0nbzt5Kw</a></span></div>
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<span style="font-size: 10pt;">fermentation – </span></div>
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<span style="font-size: 10pt;"><a href="http://biology.clc.uc.edu/courses/bio104/cellresp.htm">http://biology.clc.uc.edu/courses/bio104/cellresp.htm</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.csub.edu/~kszick_miranda/Fermentation.doc"><span style="font-style: normal;">www.csub.edu/~kszick_miranda/Fermentation.doc</span></a></span></cite><cite><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"></span></cite></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"><a href="http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/glycolysis.htm">http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/glycolysis.htm</a></span></cite></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt; font-style: normal;"><a href="http://serendip.brynmawr.edu/sci_edu/waldron/">http://serendip.brynmawr.edu/sci_edu/waldron/</a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.umsl.edu/~microbes/activities.html">http://www.umsl.edu/~microbes/activities.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.exploratorium.edu/cooking/bread/activity-yeast.html">http://www.exploratorium.edu/cooking/bread/activity-yeast.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://kenpitts.net/bio/energy/yeast_fermentation_lab.htm">http://kenpitts.net/bio/energy/yeast_fermentation_lab.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://teachers.net/lessons/posts/1229.html">http://teachers.net/lessons/posts/1229.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.thefreshloaf.com/keyword/lactic-acid-fermentation">http://www.thefreshloaf.com/keyword/lactic-acid-fermentation</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.phschool.com/science/biology_place/biocoach/cellresp/review5a.html">http://www.phschool.com/science/biology_place/biocoach/cellresp/review5a.html</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com16tag:blogger.com,1999:blog-8136765635696545893.post-68272583245833237162017-11-23T06:00:00.000-05:002017-11-23T06:00:04.598-05:00Life Outside The Chromosome<div class="MsoNormal">
Biology concepts – plasmid, linear organelle genomes, extrachromosomal circular DNAs, conjugation, </div>
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<span style="font-size: 10pt;">Planet of the Apes (1968) – a good movie, but not a great movie.</span></div>
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<span style="font-size: 10pt;">Every ape was a ventriloquist; you never saw their lips move. </span></div>
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<span style="font-size: 10pt;">But it did have the first reciprocal interspecies kiss. The pan and</span></div>
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<span style="font-size: 10pt;">scan version loses the, see no evil, hear no evil, speak no evil joke; </span></div>
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<span style="font-size: 10pt;">you only see what is in the red box.</span></div>
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I love older movies, but only if shown in full aspect (wide screen or letterbox format). So much of old cinema had interesting things going on outside the field of focus. Take Charlton Heston testifying before the panel of apes in Planet of the Apes. In the pan and scan version, you see one ape covering his ears when he doesn’t like what Heston is saying, but you miss the other two apes – one is covering his eyes and one is covering his mouth! You only get the joke in wide <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">screen</span>.</div>
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Biology can be the same. So much emphasis is placed on chromosomal DNA that we sometimes miss interesting things going on elsewhere, or we start to investigate years later than we might have if we would just look at the whole picture.</div>
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Last week we focused on the big DNA in prokaryotes, the <a href="http://biologicalexceptions.blogspot.com/2012/04/on-geometry-and-genomes.html">chromosome(s)</a>. But this doesn’t mean prokaryotes don’t have other DNA. Most prokaryotes have extrachromosomal DNA in the form of <b>plasmids</b> (plasma = shape, and id = belonging to). These are smaller loops of DNA that have fewer genes than a chromosome, and the genes are not essential for survival.<br />
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However, "smaller than chromosomes" doesn't mean they have to be small. The "megaplasmids" are over 100,000 nucleotides, and can be more than 2 million nucleotides in length, but even these are smaller than the chromosome. The exception might be in bacteria that have multiple chromosomes. Often one chromosome is much smaller; a megaplasmid could be larger than the secondary chromosome.<br />
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Plasmids replicate on their own, so sometimes they are called <b>autonomously replicating elements</b>. As such, they do not depend on the chromosome for their existence. Plasmids have internal control features that keep the number of a certain plasmid within limits in any one bacterium. <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Some plasmids</span> have other controls that keep certain plasmid types from surviving in cells that have other types of plasmids. But this doesn’t mean that a cell may have only one type of plasmid. Our lyme disease-causing example of last week, <i>B. burgdorferi</i>, has 21 different plasmids. What is more, some are linear and some are circular. It just can’t help but be an exception in all things molecular.</div>
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<span style="font-size: 10pt;">The plasmid is different from the chromosome. It is </span></div>
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<span style="font-size: 10pt;">smaller and is not tethered to the cell membrane.</span></div>
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<span style="font-size: 10pt;">New data is showing that eukaryotes also possess</span></div>
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<span style="font-size: 10pt;">plasmids, especially yeast. They are being used to</span></div>
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Even though plasmids do not carry genes essential for survival, they can still have an influence on the life of the cell. For instance, most antibacterial resistance genes are carried on plasmids. These <b>extrachromosomal elements</b> can be transferred from bacterium to bacterium, and can be passed on to the daughter cells, producing populations of bacteria that can laugh at our puny efforts to kill them. </div>
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Plasmids may also transfer metabolic genes, allowing the recipient cell to degrade other sources of food, or virulence genes, allowing them to colonize different portions of the body. This is sometimes what happens with <i>E. coli. </i> Species that live in the large bowel pick up a plasmid that codes for a system that lets them cling to the wall of the small intestine, higher in the gastrointestinal tract. Having them live here can cause diarrhea in several different ways, but it all depends on the presence or absence of that plasmid.</div>
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One type of plasmid, called the F plasmid, has a role in bacterial sex determination. O.K., it isn’t like the sexes we think usually think of; bacteria with the F plasmid are considered F<sup>+</sup> or “male” and those without are considered F<sup>-</sup> or “female.” The F plasmid codes for proteins that will create a tube (<b>pilus</b>) that can link one bacterium to another and permit the replicated F plasmid to be transferred to the F<sup>-</sup> cell, thereby turning a female in to a male. Tada – sex change the easy way.</div>
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<span style="font-size: 10pt;">The F plasmid contains <i>tra</i> genes that build the pilus</span></div>
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<span style="font-size: 10pt;">and control the integration of the DNA into the</span></div>
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<span style="font-size: 10pt;">chromosome. Helicase, the enzyme that unwinds </span></div>
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<span style="font-size: 10pt;">DNA for replication or insertion, was first identified </span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Most of the time this is not</span> such a big deal, but sometimes the F plasmid sequences can integrate into the chromosome of the bacterium, and when it cuts itself back out and becomes circular again, it may bring piece of the chromosome as well. This is now a F’ plasmid. When the F’ gets transferred to a F<sup>-</sup> cell, it takes those chromosomal sequences with it. This is one important source of genetic diversity in bacteria, called <b>conjugation</b>.</div>
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Plasmids are an integral part of the prokaryotic genome, so I have never considered them exceptions. What is more, you and I both know that there are circular DNAs in eukaryotic cells. Remember that the mitochondrion and chloroplast have their own chromosomes, although significantly reduced from what they had when captured by our ancestor cells underwent <a href="http://biologicalexceptions.blogspot.com/2012/04/evolution-of-cooperation.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">endosymbiosis</span></a>. </div>
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Since the organelles were derived from prokaryotes, it would follow that their DNA is kept in a single, circular chromosome. In most cases this is true, but there are those organisms that demonstrate linear organelle DNA or multiple chromosomes in their organelles.</div>
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For example, the human blood sucking louse <i>Pediculus humanus</i> doesn’t have a single mitochondrial chromosome. Its 34 remaining mitochondrial genes are housed on 18 separate minichromosomes. Why ? – IDK (with a nod to my texting children). Even stranger, the fungus <i>Candida parapsilosis</i> has a linear mitochondrial genome, while its very close relative, the human pathogen <i>C. albicans</i>, has a conventional mitochondrial genome geometry. </div>
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<span style="font-size: 10pt;">The moon jellyfish is a cnidarian. Cnidarins are named </span></div>
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<span style="font-size: 10pt;">for cnidocytes, the stingers that allow them to defend</span></div>
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<span style="font-size: 10pt;">themselves or catch food. However, the sea turtle is</span></div>
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<span style="font-size: 10pt;">immune to the toxin of the moon jelly, so they are</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Many</span> other examples of linear organelle chromosomes exist, especially in the <b>cnidarians</b> (animals like corals and jellyfish). The relationships between these groups, phylogenetically speaking, have been hard to work out. The evidence that the <b>hydrozoans</b> (like the fire coral and the Portugese man-o-war) and <b>scyphozoans</b> (like moon jellyfish) have linear mitochondrial genomes indicate that they are probably closely related to each other and are younger than the other groups of cnidarians, like <b>anthozoans</b> (most corals and sea anemones). </div>
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Finally, corn (maize, species name <i>Zea mays</i>) cells have been show to have linear, complex, and circular forms of the chloroplast genome. In seedlings, the areas of high cellular division seem to be more active in the linear copies of the chloroplast chromosome. This may indicate that while the circular form is still present, it is the linear form that is functional in the <i>Z. mays</i> cells. Maybe we are catching a peak at evolution in action.</div>
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Most prokaryotes have circular chromosomes, and most eukaryotic species have organelles with circular chromosomes. It would follow that the instances of linearization of mitochondrial or chloroplasts sequences occurred after endosymbiosis was established, but why? What is their advantage? What would the text abbreviation be for “nobody knows?”</div>
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The above examples indicate that extrachromosomal DNA in eukaryotes can be more dynamic than previously surmised. But we haven’t touched on the interesting part. Eukaryotic linear chromosomes can sometimes give rise to circular pieces of DNA that then replicate on their own and stick around for varying lengths of time, just like plasmids.</div>
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Probably for reasons of "species prejudice" we don’t use the term plasmid for circular DNA in higher organisms; it makes us sound too similar to our prokaryotic ancestors. Circular DNA in plants and animals is called <b>extrachromosomal circular DNA</b> (eccDNA) or <b>small poly-dispersed circular DNA</b> (spcDNA) – and the scientists are right, these sound much more advanced: a plasmid that a eukaryote can be proud of.</div>
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The sources of these eccDNA sequences are several. They can be formed from non-coding DNA (sequences that don’t lead to the production of a particular RNA or protein), or they can be derived from tandem repeat (two copies of the same gene) DNA that are plentiful in the eukaryotic genome. <a href="http://www.sciencemag.org/content/336/6077/82.abstract?sid=f190e97f-ef0d-40d7-90a4-36b4a0f9af97">A June, 2012 study</a> identified a new type of eccDNA in mice and humans that actually has coding sequences that are non-repetitive.</div>
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eccDNA has been found in every species in which it has been looked for, so its presence is not unusual. What is unusual is that eccDNA can come and go, and can be formed from normal intrachromosomal recombination (the crossing over of sequences within one chromosome) or by the looping out of sequences from a chromosome and then being cut out. As of now, we don’t know what controls their occurrence or why they form.</div>
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Importantly, they do seem to have a function. Small numbers are seen in normal cells, but the number is increased in cancer cells or normal cells that have been exposed to cancer-causing or DNA-damaging agents. This was first demonstrated using a cancer cell line called HeLa, named for the mother from whom they were isolated, <b>He</b>nrietta <b>La</b>cks. I highly recommend the biography of her tumor cells called, <u>The Immortal Life of Henrietta Lacks</u>, authored by Rebecca Skloot.</div>
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<i><span style="font-size: 10pt;">Xenopus laevis</span></i><span style="font-size: 11pt;"> is a good model organism for</span></div>
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<span style="font-size: 10pt;">Studying development. Notice how the tadpole</span></div>
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<span style="font-size: 10pt;">Only takes 3 days to develop into a tadpole, and </span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The function</span> of eccDNA in normal tissues is suggested by a study in <i>Xenopus laevis</i>, the African clawed frog. This animal is a much used model for studies of development because the eggs and embryos are big, the frogs can be induced to mate year round, and the embryos develop outside the body.</div>
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During development of the embryo, different levels of eccDNA are seen. Some sequences are seen early, while different sequences are seen later, and most of the eccDNA is gone by the time the embryos mature to tadpoles. This suggests specific functions for eccDNA in normal development. We wish we knew what the specific functions are – again, your opportunity for a Nobel Prize. </div>
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The type of eccDNA in <i>X. laevis</i> is called a <b>t-loop circle</b>. The “t” stands for <b>telomeres</b>, like we mentioned <a href="http://biologicalexceptions.blogspot.com/2012/04/on-geometry-and-genomes.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">last week</span></a>. Telomeres have many units of a repeated sequence and are used to help replicate the ends of linear chromosomes. We have talked about how each replication of the chromosome leads to a slightly shorter telomere and how some scientists hypothesize that telomere shortening has something to do with aging defects.</div>
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Early in development, embryonic cells are dividing rapidly; in the 4-week human embryo, new cells are produced at a rate of 1 million/second! All this cell division requires replication, and replication shortens the telomeres. Could it be that the t-loop circle eccDNA has a function in preserving telomere length? </div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkqOAM8AWphfYjpmpyN5R48m6G4sq4PBM9OoLLR_oGkiEIliVnkBlTEC16lghCeSTY8eHw70gFAt1yAc76VOgFrpIzRAqWh567jjUe7m3wNW7HaBYCEnUqGkcNe6hU3YbhthRWGulpEuND/s1600/telomere.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="267" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkqOAM8AWphfYjpmpyN5R48m6G4sq4PBM9OoLLR_oGkiEIliVnkBlTEC16lghCeSTY8eHw70gFAt1yAc76VOgFrpIzRAqWh567jjUe7m3wNW7HaBYCEnUqGkcNe6hU3YbhthRWGulpEuND/s320/telomere.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">The telomere has many copies of a repeat sequence. Each repeat </span><br />
<span style="font-size: 10pt;">is recognized by an enzyme that helps to replicate that end of </span><br />
<span style="font-size: 10pt;">the chromosome. The enzyme called <b>telomerase</b> contains </span><br />
<span style="font-size: 10pt;">an RNA primer that can’t be converted to DNA, so the last </span></div>
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<span style="font-family: "cambria"; font-size: 10pt;">repeat is always lost. The telomere gets shorter with every </span><br />
<span style="font-family: "cambria"; font-size: 10pt;">replication. Sooner or later, this is going to cause a problem.</span> </div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">A study</span> in 2002 suggested just that, these eccDNA telomere sequences might serve as a reserve of long telomeric sequences. These repeats could later be added back on to the telomeres through recombination events, thus preserving telomere length despite high levels of chromosome replication. </div>
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One the other hand, eccDNA is more plentiful in ageing cells and damaged cells. This might be an attempt to save the cell from the defects induced by telomere shortening or by damaging agents, or it may have a completely different function, perhaps even to induce cell suicide (<b>apoptosis</b>), so as to prevent damage to other cells. Once again, the small DNAs that are so easy to ignore may very well be the ones that allow us to live.</div>
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We have talked directly and indirectly about the mitochondria for the past few weeks; a crucial structure for energy production. Next time lets talk about the organisms that think they can do without this organelle.</div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Science&rft_id=info%3Adoi%2F10.1126%2Fscience.1213307&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Extrachromosomal+MicroDNAs+and+Chromosomal+Microdeletions+in+Normal+Tissues&rft.issn=0036-8075&rft.date=2012&rft.volume=336&rft.issue=6077&rft.spage=82&rft.epage=86&rft.artnum=http%3A%2F%2Fwww.sciencemag.org%2Fcgi%2Fdoi%2F10.1126%2Fscience.1213307&rft.au=Shibata%2C+Y.&rft.au=Kumar%2C+P.&rft.au=Layer%2C+R.&rft.au=Willcox%2C+S.&rft.au=Gagan%2C+J.&rft.au=Griffith%2C+J.&rft.au=Dutta%2C+A.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CBiochemistry%2C+Cell+Biology%2C+Molecular+Biology">Shibata, Y., Kumar, P., Layer, R., Willcox, S., Gagan, J., Griffith, J., & Dutta, A. (2012). Extrachromosomal MicroDNAs and Chromosomal Microdeletions in Normal Tissues <span style="font-style: italic;">Science, 336</span> (6077), 82-86 DOI: <a href="http://dx.doi.org/10.1126/science.1213307" rev="review">10.1126/science.1213307</a></span>
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<span style="font-size: 10pt;">For additional information or classroom activities about plasmids, extrachromosomal DNA, or telomeres, see:</span></div>
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<span style="font-size: 10pt;">Plasmids – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.plasmid.org/">http://www.plasmid.org/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://askabiologist.asu.edu/plasmids">http://askabiologist.asu.edu/plasmids</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.csun.edu/~hcbio027/biotechnology/lec2/PL/pl.htm">http://www.csun.edu/~hcbio027/biotechnology/lec2/PL/pl.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://histmicro.yale.edu/mainfram.htm">http://histmicro.yale.edu/mainfram.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/RecombinantDNA.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/RecombinantDNA.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.carolina.com/category/teacher%20resources/classroom%20activities/plasmid%20mapping%20exercises.do">http://www.carolina.com/category/teacher%20resources/classroom%20activities/plasmid%20mapping%20exercises.do</a></span></div>
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<span style="font-size: 10pt;"><a href="https://sites.google.com/site/macclassroom/student-of-the-month/plasmidmappingproblem">https://sites.google.com/site/macclassroom/student-of-the-month/plasmidmappingproblem</a></span></div>
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<span style="font-size: 10pt;"><a href="http://education.llnl.gov/bep/science/10/tLect.html">http://education.llnl.gov/bep/science/10/tLect.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/nova/teachers/activities/0303_04_nsn.html">http://www.pbs.org/wgbh/nova/teachers/activities/0303_04_nsn.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.accessexcellence.org/MTC/96PT/Share/clark.php">http://www.accessexcellence.org/MTC/96PT/Share/clark.php</a></span></div>
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<span style="font-size: 10pt;"><a href="http://agsci.oregonstate.edu/aquatic-bt/book/export/html/81">http://agsci.oregonstate.edu/aquatic-bt/book/export/html/81</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.scienceprofonline.com/microbiology/bacterial-genetics-plasmid-dna-conjugation-gene-transfer.html">http://www.scienceprofonline.com/microbiology/bacterial-genetics-plasmid-dna-conjugation-gene-transfer.html</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.biologyjunction.com/ecoli%20insulin%20factory.pdf"><span style="font-style: normal;">www.biologyjunction.com/ecoli%20insulin%20factory.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.explorebiology.com/regentsbiology/labs/">http://www.explorebiology.com/regentsbiology/labs/</a></span></div>
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<span style="font-size: 10pt;">Extrachromosomal DNA – </span></div>
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<span style="font-size: 10pt;"><a href="http://phys.org/news/2012-03-extra-chromosomal-dna.html">http://phys.org/news/2012-03-extra-chromosomal-dna.html</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.pnas.org/content/81/22/7212.full.pdf"><span style="font-style: normal;">www.pnas.org/content/81/22/7212.full.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/embor/journal/v3/n12/full/embor018.html">http://www.nature.com/embor/journal/v3/n12/full/embor018.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.bio.net/bionet/mm/ageing/2001-April/004400.html">http://www.bio.net/bionet/mm/ageing/2001-April/004400.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/plasmids/yeast-plasmid.html">http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/plasmids/yeast-plasmid.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/onc/journal/v14/n8/abs/1200917a.html">http://www.nature.com/onc/journal/v14/n8/abs/1200917a.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/onc/journal/v17/n26/abs/1202250a.html">http://www.nature.com/onc/journal/v17/n26/abs/1202250a.html</a></span></div>
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<span style="font-size: 10pt;">Telomeres - </span></div>
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<span style="font-size: 10pt;"><a href="http://www.juliantrubin.com/encyclopedia/genetics/telomere_length.html">http://www.juliantrubin.com/encyclopedia/genetics/telomere_length.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Telomeres.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Telomeres.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.sciencedaily.com/releases/2012/03/120312101437.htm">http://www.sciencedaily.com/releases/2012/03/120312101437.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.healthiertalk.com/telomere-biology-anti-aging-comes-age-2623">http://www.healthiertalk.com/telomere-biology-anti-aging-comes-age-2623</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.news-medical.net/health/Telomere-What-are-Telomeres.aspx">http://www.news-medical.net/health/Telomere-What-are-Telomeres.aspx</a></span></div>
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<span style="font-size: 10pt;"><a href="http://learn.genetics.utah.edu/content/begin/traits/telomeres/">http://learn.genetics.utah.edu/content/begin/traits/telomeres/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://telomeres.net/">http://telomeres.net/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nobelprize.org/nobel_prizes/medicine/laureates/2009/press.html">http://www.nobelprize.org/nobel_prizes/medicine/laureates/2009/press.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://mcb.berkeley.edu/courses/mcb135k/telomeres.html">http://mcb.berkeley.edu/courses/mcb135k/telomeres.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://longevity.about.com/od/whyweage/a/telomere_shortening.htm">http://longevity.about.com/od/whyweage/a/telomere_shortening.htm</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.terraternal.com/Files/TelomereShorteningAndAging.pdf"><span style="font-style: normal;">www.terraternal.com/Files/</span><b><span style="font-style: normal;">TelomereShortening</span></b><span style="font-style: normal;">AndAging.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.slideshare.net/kb62591b/telomere-shortening-implications-11163257">http://www.slideshare.net/kb62591b/telomere-shortening-implications-11163257</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1tag:blogger.com,1999:blog-8136765635696545893.post-70640333867121899802017-11-16T06:00:00.000-05:002017-11-16T06:00:05.843-05:00On Geometry And Genomes<div class="MsoNormal">
Biology concepts – <u>linear chromosomes</u>, <u>circular chromosomes</u>, <u>taxonomy</u>, <u>replication</u>, <u>telomere</u></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9Oe1HnuP1efBKu41B20DgAk8QownQR_R-XS34Yz6_kCd-Ft0ktp-UtERjcP7EqKcluwcaNn5oSGZ8KazYmN27e_tBA3I-hDbYnzYHDq9QwUyEZRN6l7xLD3dGRJlc81lyrwoiy_-v0c_9/s1600/1-organization.JPG" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9Oe1HnuP1efBKu41B20DgAk8QownQR_R-XS34Yz6_kCd-Ft0ktp-UtERjcP7EqKcluwcaNn5oSGZ8KazYmN27e_tBA3I-hDbYnzYHDq9QwUyEZRN6l7xLD3dGRJlc81lyrwoiy_-v0c_9/s1600/1-organization.JPG" /></a></td></tr>
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<span style="font-size: 10pt;">Organization is helpful in learning and work, </span></div>
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<span style="font-size: 10pt;">and apparently in crafts. But there is a fine </span></div>
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<span style="font-size: 10pt;">line between organization and obsessive </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">compulsive disorder.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Everyone</span> (teenagers excepted) knows that getting organized helps you to learn and work. When you group tasks, items, or facts, it helps in remembering or working with them. In biology, grouping organisms has a history as old as language. </div>
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In the older grouping systems, the name of an organism was a phrase that described some characteristic of the organism. When a new relative was identified, the name phrase had to be lengthened to separate this new organism from those similar to it. As you can imagine, the names got very long very fast.</div>
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In the 1750’s, Carolus Linnaeus developed a much easier system of naming. In his “trivial system,” each organism had two descriptors in its name; a binary naming system. Linnaeus’ system (and others) of <b>taxonomy</b> (taxis is Greek for “arrangement”) is based on shared characteristics. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_R4hT4It89Ln3G7ZM3AAPDt9TEJHN8Zj4kjf2OBf0G57Uv7RxUc4Vx36YFdu5GKZiatXzEc5o1CdFItG6HuyfHOgN0TWk4W9WhVsWJS8zdq3JuyENY6klpDYJhfwQ_5pjYV4n5ZbGJUKT/s1600/2-Linnaeus.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_R4hT4It89Ln3G7ZM3AAPDt9TEJHN8Zj4kjf2OBf0G57Uv7RxUc4Vx36YFdu5GKZiatXzEc5o1CdFItG6HuyfHOgN0TWk4W9WhVsWJS8zdq3JuyENY6klpDYJhfwQ_5pjYV4n5ZbGJUKT/s320/2-Linnaeus.jpg" width="265" /></a></td></tr>
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<span style="font-size: 10pt;">Carolus Linnaeus (he let me call him Carl) had many </span></div>
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<span style="font-size: 10pt;">names. His knighthood name was Carl von Linne, his </span></div>
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<span style="font-size: 10pt;">born name was Carl Nilsson Linnaeus. In his naming </span></div>
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<span style="font-size: 10pt;">system Linne came up with the name mammal, so I guess </span></div>
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<span style="font-size: 10pt;">he named himself again.</span></div>
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At first, it was the characteristics people could see that were used to group organisms. Then it was the characteristics on the macroscopic and the microscopic levels. Now it is based on molecular characteristics, forming both a taxonomic classification and an evolutionary tree; this is now called the science of <b style="background-color: white;"><span style="-moz-background-clip: border; -moz-background-origin: padding; -moz-background-size: auto auto; background-attachment: scroll; background-image: none; background-position: 0% 0%; background-repeat: repeat;">phylogenetics</span></b>.<b> </b></div>
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Molecular characteristics usually mean DNA. Differences in DNA sequence and in the number of mutations that have occurred provide a relationship between organisms. Using these factors, a time line for their divergence can be estimated. We changed the ways we determine similarity, and that changed the rules. With new rules come new exceptions.</div>
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Many of the DNA rules start with <b>chromosomes</b> (chromo = color and soma = body, this comes from the dark and light banding pattern of stained DNA). Cellular DNA is very long and very thin, perhaps only 12-22 nanometers wide (about 1/5000 the width of a human hair). In this form, it can only be seen with an electron microscope. </div>
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In eukaryotes, this DNA becomes complexed with many proteins during cell division so that all the DNA can be packed up and moved more easily to the daughter cells. Called <b>chromosomal packaging</b>, the DNA is wound around proteins called histones, then folded many times over, so that the finished chromosome is packed 10,000 times more compact than the original DNA helix. This is the packed DNA that we see as dark and light bands and gives it its name.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLkIQfKBhF45bBmAEd4qrL5lwEkdoc6HBdeRGTXxpD37MLLp6_oSA8YlB48FDyc44QTYfcgRaqeFhAS4ZzrSZoMbgROzMPI_3y9sShJe2Lr1lRB9ufo-jDXPuqfhVICO_GR5TaEUp6m1Nr/s1600/3-packing.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLkIQfKBhF45bBmAEd4qrL5lwEkdoc6HBdeRGTXxpD37MLLp6_oSA8YlB48FDyc44QTYfcgRaqeFhAS4ZzrSZoMbgROzMPI_3y9sShJe2Lr1lRB9ufo-jDXPuqfhVICO_GR5TaEUp6m1Nr/s400/3-packing.gif" width="393" /></a></td></tr>
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<span style="font-size: 10pt;">DNA packaging with proteins is a eukaryotic characteristic, unless </span></div>
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<span style="font-size: 10pt;">I find an exception! The DNA wraps around the histones, then the </span></div>
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<span style="font-size: 10pt;">histones line up into a coil, then the coils fold up into the </span></div>
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<span style="font-size: 10pt;">chromatid. Total packing – about 10,000 fold; it takes a piece of </span></div>
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<span style="font-size: 10pt;">DNA 1.5 cm long and makes it 0.0000002 cm long!</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">By definition</span>, a chromosome is a piece of DNA that contains genes that are essential for the survival and function of the organism. This implies that there may be other pieces of DNA that contain genes that are not necessary for survival. </div>
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The molecular rules of biology state that prokaryotes have one chromosome, a single piece of double stranded DNA that contains all the genes that the prokaryote (archaea or bacteria) needs. This is efficient for the organism; it is one stop shopping for replication of all its instructions and only two chromosomes (after replication) need to be segregated to the two daughter cells that are being made. </div>
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And here begins our exceptions. There are several prokaryotic organisms that have more than one chromosome. That is to say, their essential genes are located on more than one piece of DNA.</div>
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The first identified example of multiple chromosomes in a prokaryote was <i>Rhodobacter sphaeroides</i>, a photosynthetic species of true bacteria that can also break down carbohydrates it takes up. This bacterium was found to have two chromosomes, although one was more than three times the size of the other. </div>
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Genes encoding essential products for making proteins and carrying out day-to-day functions are located on each of the two <i>R. sphaeroides </i>circular chromosomes. There are other genes that exist on both of the chromosomes, but appear to be turned on and off via different signals. This implies that the same gene may serve its function at different times in the organism's life, or under different environmental conditions.</div>
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<i>R. sphaeroides</i> is by no means the only prokaryote that possesses multiple chromosomes. More than a dozen different groups of bacteria have at least some members with more than one chromosome. This includes <i>Vibrio cholerae</i>, the causative organism of the disease cholera. <i>V. cholerae</i> is responsible for a diarrheal infection that affects more than 3-5 million people per year and causes 130,000 deaths each year. </div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYMMiflFtzT8Ntu5iGFkv4QlUjKZtHJm6elo2hvmZQz5h3qPOZZ7ObdKld8UGjmimpHrwPwnFw-AUVal0xbMxJ7oF2Yn8di46B5LL1EyGYExWI3He5f4mHGJEB9sGuGu1tdchH-4aIIpNV/s1600/4-crown+gall.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYMMiflFtzT8Ntu5iGFkv4QlUjKZtHJm6elo2hvmZQz5h3qPOZZ7ObdKld8UGjmimpHrwPwnFw-AUVal0xbMxJ7oF2Yn8di46B5LL1EyGYExWI3He5f4mHGJEB9sGuGu1tdchH-4aIIpNV/s320/4-crown+gall.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="font-size: 10pt;">This is a crown gall in a birch tree caused by <i>R. radiobacter</i>. </span></div>
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<span style="font-size: 10pt;">Like in cancer tumor in animal tissues, a gallis unregulated </span><br />
<span style="font-size: 10pt;">growth. In grape vines, it has been responsible for the ruin </span><br />
<span style="font-size: 10pt;">of entire Kentucky vineyards. Kentucky makes wine?</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">In addition</span> to these organisms there is <i>Agrobacterium tumefaciens</i>, whose name was recently changed to <i>Rhizobium radiobacter</i>. This is a very interesting two chromosome bacterium. It usually is a pathogen of plants, forming galls (tumors) on several cash crops, such as nut trees and grape vines. This is an important tool in the molecular biologist’s toolbox, since it has been found that <i>R. radiobacter </i>easily transfers DNA between itself and the plants it infects, via lateral gene transfer (a subject we have discussed in depth, <a href="http://biologicalexceptions.blogspot.com/2011/08/when-amazing-isnt-enough-sea-slug.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">When Amazing Isn’t Enough</span></a> and <a href="http://biologicalexceptions.blogspot.com/2012/04/evolution-of-cooperation.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Evolution of Cooperation</span></a>). But <i>R. radiobacter</i> goes further, it can also cause disease in humans who have poorly functioning immune systems. For folks battling cancers, HIV, or other diseases that wreak havoc with their ability to fight off infections, <i>R. radiobacter</i> can cause bacteremia (bacteria colonizing the blood) or endopthalmitis (infection of the two hollow cavities of the eye). </div>
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The second molecular rule of biology is that prokaryotic chromosomes take the shape of a circle; the DNA forms a single loop. This shape is helpful in terms of replicating the prokaryotic chromosome prior to cell division. Start anywhere, and you can keep going to replicate the entire thing. In point of fact, they don’t start just anywhere, but one start point (called an <b>origin of replication</b>) leads to complete replication.</div>
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There are advantages to having a circular chromosome. Prokaryotic chromosomes do not complex with proteins to become more densely packed, so it remains as a thin, long molecule. This means that fewer proteins are needed to maintain a circular, prokaryotic chromosome. In addition, since replication requires the doubling of just one piece of DNA from one origin of replication, this takes less time and fewer proteins to accomplish. Together, these features of a circular chromosome result in a more efficient and simpler process, with fewer chances for mistakes to be made.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixLz1L-IgTyaWltajoCCnKSAjYxuuf5RND_xiHd6hxRTe6zbleZgQ7w2olAuKkxWSQkQXzMInFxHYWNsgAyDSfcqcPaKmcgLCa8tvMiWha0vgshVLeP6rSxQVF8nq_CKH-mKS1-yhKPjpp/s1600/5-borrelia.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixLz1L-IgTyaWltajoCCnKSAjYxuuf5RND_xiHd6hxRTe6zbleZgQ7w2olAuKkxWSQkQXzMInFxHYWNsgAyDSfcqcPaKmcgLCa8tvMiWha0vgshVLeP6rSxQVF8nq_CKH-mKS1-yhKPjpp/s320/5-borrelia.gif" width="314" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<i><span style="font-size: 10pt;">Borrelia burgdorferi</span></i><span style="font-size: 11pt;">, a spirochete (spiral) bacterium was</span></div>
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<span style="font-size: 10pt;">Named for the researcher who discovered, it in 1982, Willy</span></div>
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<span style="font-size: 10pt;">Burgdorfer. It is one of the few pathogens that can function</span></div>
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<span style="font-size: 10pt;">without iron; it uses manganese instead. The ways this bug</span></div>
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<span style="font-size: 10pt;">gets around the rules is astounding.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">However</span>, there are exceptions in which prokaryotes have linear chromosomes. The <i>Borrelia burgdorferi</i> bacterium has a single chromosome, but it has the geometry of eukaryotic chromosomes, a line segment with two ends. This was the first prokaryote found to have a linear genome, way back in 1989. This <b>lyme disease</b> pathogen has one major linear chromosome and other pieces of smaller DNA that are circular or linear (which we will discuss in the next post); you just can’t trust a pathogen to follow the rules. Other prokaryotes that have linear chromosomes include our friend <i>R. radiobacter</i>. Even more interesting, while this pathogen has two chromosomes; one is circular and one is linear. How does that happen?</div>
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The previous discussions do not mean that all prokaryotes with multiple chromosomes or linear chromosomes are disease-causing agents, just the interesting ones. Since they cause pathology in animals or crops, they hit us in the wallet. It makes sense that we have studied them in more detail and have discovered their hidden exceptions. There are probably thousands of innocuous prokaryotes that have more than one chromosome or have linear chromosomes, we just don’t have a reason to look at them in that much detail.</div>
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There may be more than one way that prokaryotes end up with linear chromosomes. In some cases, the linear chromosomes still have bacterial origins of replication, indicating that they may have evolved from circular chromosomes. There is also evidence that some linear chromosomes might have developed from other linear DNAs in the cell, something we will talk about next time.</div>
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The rules of defining prokaryotes and eukaryotes also state that eukaryotes have linear chromosomes. The essential genes are stored on more than one piece of DNA, and these pieces have two ends apiece, like a line segment in geometry.<span style="font-family: "times"; font-size: 10pt;"></span></div>
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Linear chromosomes are a disadvantage because it is hard to replicate the ends. Because of the way that DNA replicates, the ends of the chromosomes, called <b>telomeres</b>, end up being shortened every time the DNA is replicated. Over time, this leads to shorter chromosomes that might lose DNA sequences that the cell needs in order to function. </div>
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<br /></div>
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Some lines of evidence suggest that telomere shortening is a direct cause of ageing. The loss of important sequences at the ends of chromosomes cases cells to perform at less than optimal levels, and mistakes and toxic products then build up and lead to larger dysfunctions of cells, organs, and systems, ie. getting old. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEonjL61NmIi7I9HLctkj8DZLmUNA_-KXiZmjw9nXh5qVtbUIg0WSrDgrOznWtC-aUDYUnmX0Zq6eZ3G0doAsBQfCKGGZ9dSN_16gqbV1Ub908fFIYiVniDkADmX_inxHi1CsE-xQTmxKZ/s1600/6-recomb.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="166" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEonjL61NmIi7I9HLctkj8DZLmUNA_-KXiZmjw9nXh5qVtbUIg0WSrDgrOznWtC-aUDYUnmX0Zq6eZ3G0doAsBQfCKGGZ9dSN_16gqbV1Ub908fFIYiVniDkADmX_inxHi1CsE-xQTmxKZ/s400/6-recomb.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 10pt;">This is a very simple cartoon depicting recombination. When</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">sequences are exchanged, it isn’t necessarily a 1:1 exchange. </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">Sometimes parts of genes are sent one way but not the other,</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">So new genetic sequences can result. Some help, some hurt, and</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">some have no effect until the environmental conditions show</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">them for what they are. Most exchanges do not increase diversity</span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;">to any great degree, but the fact that some do has helped move</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">evolution along.</span> </td></tr>
</tbody></table>
<div class="MsoNormal">
On the other hand, linear chromosomes may promote genetic diversity. In eukaryotes, the division of the cell requires each chromosome to be replicated, then the matching chromosomes of a pair (one from mom and one from dad) line up together. This is a prime opportunity for the chromosome to exchange some sequences in a process called <b>homologous recombination</b>; a mixing of genes beyond just getting one from each <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">parent</span>.</div>
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<br /></div>
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However, a study published in 2010 indicates that the geometry of the chromosome doesn’t matter when it comes to recombination rates. Scientists took a circular chromosome organism and linearized its genome (they cut it so it had ends). They also did the reverse experiment, taking a linear chromosome organism and circularizing its DNA. </div>
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<br /></div>
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In both cases, there was no change in the rate that its DNA recombined and produced slightly different offspring (the two circular chromosomes after replication can swap some pieces). So geometry does not appear to affect genetic diversity – so why did each type evolve? Good question – that can be your Nobel Prize project. </div>
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<br /></div>
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Next week we will continue the discussion of exceptions in DNA structures, including DNA that isn’t part of a chromosome, and mitochondrial and chloroplast genomes that don’t look like they should.</div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=PloS+one&rft_id=info%3Apmid%2F22432010&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Genome+stability+of+Lyme+disease+spirochetes%3A+comparative+genomics+of+Borrelia+burgdorferi+plasmids.&rft.issn=&rft.date=2012&rft.volume=7&rft.issue=3&rft.spage=&rft.epage=&rft.artnum=&rft.au=Casjens+SR&rft.au=Mongodin+EF&rft.au=Qiu+WG&rft.au=Luft+BJ&rft.au=Schutzer+SE&rft.au=Gilcrease+EB&rft.au=Huang+WM&rft.au=Vujadinovic+M&rft.au=Aron+JK&rft.au=Vargas+LC&rft.au=Freeman+S&rft.au=Radune+D&rft.au=Weidman+JF&rft.au=Dimitrov+GI&rft.au=Khouri+HM&rft.au=Sosa+JE&rft.au=Halpin+RA&rft.au=Dunn+JJ&rft.au=Fraser+CM&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CMicrobiology+%2C+Genetics+%2C+Molecular+Biology%2C+Taxonomy%2C+Pathology">Casjens SR, Mongodin EF, Qiu WG, Luft BJ, Schutzer SE, Gilcrease EB, Huang WM, Vujadinovic M, Aron JK, Vargas LC, Freeman S, Radune D, Weidman JF, Dimitrov GI, Khouri HM, Sosa JE, Halpin RA, Dunn JJ, & Fraser CM (2012). Genome stability of Lyme disease spirochetes: comparative genomics of Borrelia burgdorferi plasmids. <span style="font-style: italic;">PloS one, 7</span> (3) PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/22432010" rev="review">22432010</a></span><br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Molecular+phylogenetics+and+evolution&rft_id=info%3Apmid%2F24440816&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Single+acquisition+of+protelomerase+gave+rise+to+speciation+of+a+large+and+diverse+clade+within+the+Agrobacterium%2FRhizobium+supercluster+characterized+by+the+presence+of+a+linear+chromid.&rft.issn=1055-7903&rft.date=2014&rft.volume=73&rft.issue=&rft.spage=202&rft.epage=7&rft.artnum=&rft.au=Ram%C3%ADrez-Bahena+MH&rft.au=Vial+L&rft.au=Lassalle+F&rft.au=Diel+B&rft.au=Chapulliot+D&rft.au=Daubin+V&rft.au=Nesme+X&rft.au=Muller+D&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Biochemistry%2C+Cell+Biology%2C+Evolutionary+Biology%2C+Genetics"><br /></span>
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Molecular+phylogenetics+and+evolution&rft_id=info%3Apmid%2F24440816&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Single+acquisition+of+protelomerase+gave+rise+to+speciation+of+a+large+and+diverse+clade+within+the+Agrobacterium%2FRhizobium+supercluster+characterized+by+the+presence+of+a+linear+chromid.&rft.issn=1055-7903&rft.date=2014&rft.volume=73&rft.issue=&rft.spage=202&rft.epage=7&rft.artnum=&rft.au=Ram%C3%ADrez-Bahena+MH&rft.au=Vial+L&rft.au=Lassalle+F&rft.au=Diel+B&rft.au=Chapulliot+D&rft.au=Daubin+V&rft.au=Nesme+X&rft.au=Muller+D&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Biochemistry%2C+Cell+Biology%2C+Evolutionary+Biology%2C+Genetics">Ramírez-Bahena MH, Vial L, Lassalle F, Diel B, Chapulliot D, Daubin V, Nesme X, & Muller D (2014). Single acquisition of protelomerase gave rise to speciation of a large and diverse clade within the Agrobacterium/Rhizobium supercluster characterized by the presence of a linear chromid. <span style="font-style: italic;">Molecular phylogenetics and evolution, 73</span>, 202-7 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/24440816" rev="review">24440816</a></span><br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+bacteriology&rft_id=info%3Apmid%2F2808300&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Physical+and+genetic+mapping+of+the+Rhodobacter+sphaeroides+2.4.1+genome%3A+presence+of+two+unique+circular+chromosomes.&rft.issn=0021-9193&rft.date=1989&rft.volume=171&rft.issue=11&rft.spage=5850&rft.epage=9&rft.artnum=&rft.au=Suwanto+A&rft.au=Kaplan+S&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Evolutionary+Biology%2C+Biochemistry%2C+Cell+Biology%2C+Molecular+Biology%2C+Genetics"><br /></span>
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+bacteriology&rft_id=info%3Apmid%2F2808300&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Physical+and+genetic+mapping+of+the+Rhodobacter+sphaeroides+2.4.1+genome%3A+presence+of+two+unique+circular+chromosomes.&rft.issn=0021-9193&rft.date=1989&rft.volume=171&rft.issue=11&rft.spage=5850&rft.epage=9&rft.artnum=&rft.au=Suwanto+A&rft.au=Kaplan+S&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Evolutionary+Biology%2C+Biochemistry%2C+Cell+Biology%2C+Molecular+Biology%2C+Genetics">Suwanto A, & Kaplan S (1989). Physical and genetic mapping of the Rhodobacter sphaeroides 2.4.1 genome: presence of two unique circular chromosomes. <span style="font-style: italic;">Journal of bacteriology, 171</span> (11), 5850-9 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/2808300" rev="review">2808300</a></span>
<br />
<br />
<br />
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<span style="font-size: 10pt;">For more information or classroom activities on prokaryotic chromosomes or eukaryotic chromosomes, see:</span></div>
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<span style="font-size: 10pt;">Prokaryotic chromosomes – </span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/chroms-genes-prots/chromosomes.html">http://www.sci.sdsu.edu/~smaloy/MicrobialGenetics/topics/chroms-genes-prots/chromosomes.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.news-medical.net/health/Chromosomes-in-Prokaryotes.aspx">http://www.news-medical.net/health/Chromosomes-in-Prokaryotes.aspx</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.biog1105-1106.org/demos/106/unit01/17b.eukchroms.html">http://www.biog1105-1106.org/demos/106/unit01/17b.eukchroms.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/scitable/topicpage/genome-packaging-in-prokaryotes-the-circular-chromosome-9113">http://www.nature.com/scitable/topicpage/genome-packaging-in-prokaryotes-the-circular-chromosome-9113</a></span></div>
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<span style="font-size: 10pt;"><a href="http://biology.kenyon.edu/courses/biol114/Chap01/chrom_struct.html">http://biology.kenyon.edu/courses/biol114/Chap01/chrom_struct.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.tusculum.edu/faculty/home/ivanlare/html/genetics/chromosome1-master.html">http://www.tusculum.edu/faculty/home/ivanlare/html/genetics/chromosome1-master.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://en.wikipedia.org/wiki/Nucleoid">http://en.wikipedia.org/wiki/Nucleoid</a></span></div>
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<span style="font-size: 10pt;"><a href="http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/bacterial_chromosome_compaction.html">http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/bacterial_chromosome_compaction.html</a></span></div>
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<span style="font-size: 10pt;">Eukaryotic chromosomes – </span></div>
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<span style="font-size: 10pt;"><a href="http://biology.kenyon.edu/courses/biol114/Chap01/chrom_struct.html">http://biology.kenyon.edu/courses/biol114/Chap01/chrom_struct.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ndsu.edu/pubweb/~mcclean/plsc431/eukarychrom/eukaryo3.htm">http://www.ndsu.edu/pubweb/~mcclean/plsc431/eukarychrom/eukaryo3.htm</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://ocw.mit.edu/high-school/biology/heredity/eukaryotic-chromosomes/">http://ocw.mit.edu/high-school/biology/heredity/eukaryotic-chromosomes/</a></span></div>
<div class="MsoNormal">
<span style="font-size: 10pt;"><a href="http://studentreader.com/eukaryotic-chromosome/">http://studentreader.com/eukaryotic-chromosome/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ndsu.edu/pubweb/~mcclean/plsc431/eukarychrom/eukaryo3.htm">http://www.ndsu.edu/pubweb/~mcclean/plsc431/eukarychrom/eukaryo3.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/scitable/topicpage/chromosomes-14121320">http://www.nature.com/scitable/topicpage/chromosomes-14121320</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.emunix.emich.edu/~rwinning/genetics/chrom.htm">http://www.emunix.emich.edu/~rwinning/genetics/chrom.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/nova/teachers/activities/2809_genome_04.html">http://www.pbs.org/wgbh/nova/teachers/activities/2809_genome_04.html</a></span></div>
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<cite><span style="font-size: 10pt;"><a href="http://www.indiana.edu/~ensiweb/lessons/chr.con2.tchr.pdf"><span style="font-style: normal;">www.indiana.edu/~ensiweb/</span><b><span style="font-style: normal;">lesson</span></b><span style="font-style: normal;">s/chr.con2.tchr.pdf</span></a></span></cite></div>
<span style="font-size: 10pt;"><a href="http://www.windows2universe.org/earth/Life/genetics_intro.html">http://www.windows2universe.org/earth/Life/genetics_intro.html</a></span>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com3tag:blogger.com,1999:blog-8136765635696545893.post-47950093908459176482017-11-09T06:00:00.000-05:002017-11-09T06:00:00.173-05:00The Evolution Of Cooperation<div class="MsoNormal">
Biology concepts – <u>biological timeline</u>, <u>serial endosymbiosis</u>, <u>endocystosis</u>, <u>evolution</u></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6sy6Z_ihGOUCNtK8o5Ogpv04fzAlohKZ7GLGMYbKRJMfJC1RbHdCBg97dS83nXSHqByvexkD4TTmvyCvGyDar7jIJQVyEf7iPsu2KBVoVx_zgyQjKaAEQlDHPDoDvL5gl5jkfgNAmBHs2/s1600/tree+of+life+tattoo.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6sy6Z_ihGOUCNtK8o5Ogpv04fzAlohKZ7GLGMYbKRJMfJC1RbHdCBg97dS83nXSHqByvexkD4TTmvyCvGyDar7jIJQVyEf7iPsu2KBVoVx_zgyQjKaAEQlDHPDoDvL5gl5jkfgNAmBHs2/s320/tree+of+life+tattoo.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">Taxonomy, the placing of species in different </span></div>
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<span style="font-size: 10pt;">groups based on their characteristics, changes</span></div>
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<span style="font-size: 10pt;">everyday – literally everyday – organisms are </span></div>
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<span style="font-size: 10pt;">placed in different groups and groups are created</span></div>
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<span style="font-size: 10pt;">and eliminated. That better be a temporary tattoo!</span></div>
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If we look at the 3.5 billion year history of life on Earth, we see that out planet was lifeless for almost a quarter of its span, and animals have been around just a short blip of time, a mere 760 million years. Often, it seems that the big numbers to get in the way of understanding the time line as a <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">whole.</span></div>
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If we treat the entire history of earth as one year, we might get a clearer picture. Earth coalesces from space dust on January 1<sup>st</sup>, but it isn’t until March 22nd that we find the first evidence of life. These most primitive fossils are of the prokaryotes called Archaea (Greek for “ancient”). Not long after this, maybe a week or so, the eubacteria and Archaea separate from one another. </div>
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Then we have to wait until August 7<sup>th</sup> to find a big change; the first eukaryotic organisms are seen. These represent a fundamental change in the organisms, having nuclei and membrane bound organelles. It's amazing that we must travel 3/4 through our one year time line before we see a cell that looks somewhat like ours!</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHeZDcXyRB_pQ_eXf6jGjcAwbCkBZzLeO867bKHn8IF_etdC9bCZd4kmEeCg2YECrDFjvj6i2zjpRm7iZU0G3K-cvzeRHC69cS75gk6p8ha1U49aUdjnxTT6J4xZ5Q2EJhaG7nmh3RJtMr/s1600/Namibia-fossils_02.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="236" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHeZDcXyRB_pQ_eXf6jGjcAwbCkBZzLeO867bKHn8IF_etdC9bCZd4kmEeCg2YECrDFjvj6i2zjpRm7iZU0G3K-cvzeRHC69cS75gk6p8ha1U49aUdjnxTT6J4xZ5Q2EJhaG7nmh3RJtMr/s320/Namibia-fossils_02.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">Here is one of the Namibia sponge fossils recently</span></div>
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<span style="font-size: 10pt;">discovered in Africa. It represents the oldest animal</span></div>
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<span style="font-size: 10pt;">in the fossil record. Just how that was recognized as a</span></div>
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<span style="font-size: 10pt;">fossil is beyond me – I think I have six of those in my</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">garden!</span> </td></tr>
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Later in the year, around October 30<sup>th</sup> at noon, we see the first animals. Fossils of Namibia sponges in Africa were first reported in February of 2012. This fossils are 100 million years older than the previously oldest animal remains, so our new data means that animals have been around for an additional week in our time line of a <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">year</span>.</div>
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Insects appear about Nov. 26<sup>th</sup>, while mammals first show up around Dec. 8<sup>th</sup>. The dinosaurs became extinct sometime in the afternoon of Dec. 26<sup>th</sup>, so they had very little time to play with their Christmas presents. <i>Homo sapiens</i> (us) didn’t appear on the doorstep looking for holiday cheer until 11:40 pm on New Years Eve, Dec. 31<sup>st</sup>!</div>
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Our time line analogy shows us that prokaryotes are the wise old ancestors; we aren’t even old enough to be rebellious teenagers, although we still think we know everything. The key question is: how did we progress to analogy-makers from single celled Archaea? If we put together several of the topics we have been discussing in the past three weeks, we may come up with an interesting step in the process. Our clues include:</div>
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1) <a href="http://biologicalexceptions.blogspot.com/2012/03/simple-aint-so-simple-anymore.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Microcompartments</span></a> exist in bacteria, like organelles, and they also exist in eukaryotic cells, especially in nucleus' function. This links eukaryotes to prokaryotes.</div>
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2) Sometimes cells will engulf objects, parts of other cells, or other cells. Depending on the size of the particle or cell, we may call this endocytosis or phagocytosis, and is similar to how we saw keratinocytes take up <a href="http://biologicalexceptions.blogspot.com/2012/03/cell-to-cell-tanning.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">melanosomes</span></a>.</div>
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3) Three eukaryotic organelles, the nucleus, the mitochondria, and the chloroplast have <a href="http://biologicalexceptions.blogspot.com/2012/03/cells-are-great-multitaskers.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">double membranes</span></a>, and they each have their own DNA.</div>
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4) There are two different types of prokaryotes, <a href="http://biologicalexceptions.blogspot.com/2012/04/extremophiles-are-key-or-archaea.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">archaea</span></a> and bacteria.</div>
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Bacterial microcompartments give prokaryotes some compartmentalization in order to carry out necessary chemical reactions. Eukaryotes also have some prokaryotic microcompartment remnants, like the nuclear vault complex. This shows crossover between prokaryotes and eukaryotes, and gives us clues about eukaryotic origins. In fact, the currently accepted theory about the evolution of organelles - the very thing that makes cells eukaryotic - has to do with both types of prokaryotes - archaea and bacteria.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmssvNjKYTnnYml1cgqaiWiktF1WLyH8YjD77IjR9JMToSEsaLsNX3LR_9ysdopyWBnVokkzVb8XWbTGLsSRyh5sPJR0Rx3SROjUDUheQ1736DK_cj3iUaUoJ6NsACtUn4hJ7aArJFTsvk/s1600/Endocytosis_types.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmssvNjKYTnnYml1cgqaiWiktF1WLyH8YjD77IjR9JMToSEsaLsNX3LR_9ysdopyWBnVokkzVb8XWbTGLsSRyh5sPJR0Rx3SROjUDUheQ1736DK_cj3iUaUoJ6NsACtUn4hJ7aArJFTsvk/s400/Endocytosis_types.png" width="400" /></a></td></tr>
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<span style="font-size: 10pt;">There are three types of endocytosis (with exceptions).</span></div>
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<span style="font-size: 10pt;">Endocystosis of large objects and cells is called <b>phagocytosis</b>.</span></div>
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<span style="font-size: 10pt;">Internalization of very small molecules and fluid is called</span></div>
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<span style="font-size: 10pt;"><b>pinocytosis</b>. Other molecules of various sizes have specific</span></div>
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<span style="font-size: 10pt;">receptors that recognize them on the cell surface. They are </span></div>
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<span style="font-size: 10pt;">brought in by <b>receptor-mediated endocytosis</b>. Notice that no</span></div>
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<span style="font-size: 10pt;">matter what method is used, the internalized particle ends up</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">surrounded by part of the cell membrane.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The key</span> to their interrelationship has to do with <b>endocytosis </b>(endo = into, cyto = cell). Most prokaryotic and eukaryotic cells eat other cells; they do it all the time – it is how <b>heterotrophic</b> <b>organisms</b> (those that can't make their own carbohydrates, ie. non-plants) gain their nutrients. We do it too, just on a larger scale; we eat millions of cells at a time; often these millions of cells can take the shape of a steak or a carrot.</div>
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When a cell, protein, other molecule is engulfed by another cell, it is wrapped in a portion of the aggressor cell’s membrane. The naked molecule is now contained in a <b>vesicle</b>, a membrane bound sac, like the melanosome. If the endocytosed material is an entire cell, something that has its own membrane, then it ends up with two membranes, just like the mitochondrion, chloroplast, and nucleus.</div>
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Most often, when one prokaryote phagocytoses another, the story is over….gulp, yum, digest. But scientists believe that long ago (sometime in the first week of August in our time line) an endocytosed cell did not go gentle into that good night. Instead, it took up residence in the cell that ate it. In this rare case, it turned out that both cells gained from the situation. </div>
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The endocytosed cell was protected from other predators and had a ready supply of nutrients from the parent cell. The captured cell made lots of ATP, but it didn’t need much because it was being supplied with everything it needed; it didn't need to make energy to move or hunt or escape. Most of its ATP production went unused. Perhaps it moved this excess ATP out into the parent cell. So the parent cell gained a source of ATP production. This was <b>mutualism</b>, a type of symbiosis in which both parties benefit. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDDv4pLob3lW8vxsYajp9FjMw_CUfehD8M7Yq56pd0NscDWO0i5ckLJcLCm1h1v4cITWuVXTpubIU25vMctCkcQKHY5IN9TerpYquYVj-NMzIZEqJfsFZhces_Zo5DL4elpalI2QlGMkhyphenhyphen/s1600/clown+mutualism.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="214" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDDv4pLob3lW8vxsYajp9FjMw_CUfehD8M7Yq56pd0NscDWO0i5ckLJcLCm1h1v4cITWuVXTpubIU25vMctCkcQKHY5IN9TerpYquYVj-NMzIZEqJfsFZhces_Zo5DL4elpalI2QlGMkhyphenhyphen/s320/clown+mutualism.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">Clownfish clean the sea anemone and keep it </span></div>
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<span style="font-size: 10pt;">parasite free. The poisonous anemone provides </span></div>
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<span style="font-size: 10pt;">a safe environment for the clown fish; no </span></div>
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<span style="font-size: 10pt;">unwanted house guests! This is a good example of</span></div>
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<span style="font-size: 10pt;">mutualistic symbiosis. Bet you didn’t know you</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">learned things from Finding Nemo.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Imagine</span> if the same thing happened with a cyanobacterium, a cell that could perform photosynthesis. The same sort of symbiosis might be set up, with the endocystosed cell providing carbohydrates and the parent cell providing protection.<br />
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Now imagine that these captured cells, the photosynthesizer and the ATP maker, replicated themselves inside their parent cells just as they would if they were outside, living on their own. They could easily do this since they still retained their own DNA and cell division mechanisms.<br />
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This is in fact what scientists believe happened. The endocytosed cells that produced extra ATP evolved into our mitochondria. Endocytosed cells that could do photosynthesis became the chloroplasts of plants. Not all cells are plants because not all cells with an ancestral mitochondria also ate a cyanobacterium. The fact that plants cells have mitochondria as well as chloroplasts tells us that plant cells developed AFTER cells with mitochondrial ancestors.<br />
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But the nucleus may be a tougher nut to crack. It may be that an endocytosed cell good at keeping DNA safe and producing ribosomes became the nucleus, by endocytosis. The data suggests that our DNA is closer to archaeal DNA than bacterial DNA, so it would have been a eubacteria endocytosing an archaea. Or perhaps the archaea invaded the bacterium rather than being endocytosed. The nucleus does have a double membrane and uses some prokaryotic microcompartments to this day, so this could make sense.</div>
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But other theories also exist, including one that says an intermediate eukaryotic cell, theoretically called a <b>chronocyte</b>, had developed some organelles on its own or by endocytosis, including a cytoskeleton. This internal structure allowed the cell become bigger, and engulf a cell large enough to evolve into the nucleus.</div>
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Another theory uses an evolutionary exception as its basis. Some aquatic bacteria, called <b>planctomycetes</b> (planktos = drifting and mycete = fungus-like), have an organized interior, with something that looks like a nucleus with pores, called a <b>nucleoid</b>. In fact, when they were first discovered, planctomycetes were mistaken for small fungal cells. However, we know they are prokaryotes by DNA sequencing. I thought prokaryotes didn’t have nuclei! Remember that in biology, there is almost always an exception. <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span> planctomycete nucleoid structure suggests that the nucleus may have evolved on its own, without endocytosis. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhy9juqyV8L5f2rx3I_cFmj3tVZGv0E9-BkcLoqqx1xzppfkboIxznq2mTonUaUqUC3iZaVTcAUuKhL2eDBQmZZ34FNgjya4wJJ8uCs0nCFVYs6wjss_RTcwYkMGHpAfSvU1ve-ih8Urz4L/s1600/planctomycete.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhy9juqyV8L5f2rx3I_cFmj3tVZGv0E9-BkcLoqqx1xzppfkboIxznq2mTonUaUqUC3iZaVTcAUuKhL2eDBQmZZ34FNgjya4wJJ8uCs0nCFVYs6wjss_RTcwYkMGHpAfSvU1ve-ih8Urz4L/s400/planctomycete.jpg" width="368" /></a></td></tr>
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<span style="font-size: 10pt;">The planctomycete species, <i>Pirellula</i> (latin for small pear),</span></div>
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<span style="font-size: 10pt;">is an exceptional bacterium. It has a primitive nucleus</span></div>
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<span style="font-size: 10pt;">and a stalk that makes it look like a eukaryotic</span></div>
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<span style="font-size: 10pt;">fungal cell. It was misidentified for a long time, and is </span></div>
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<span style="font-size: 10pt;">a prime example of why the tattoo above was a bad</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">idea!</span> </td></tr>
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Finally, another theory posits that the nucleus originated from a virus infecting a primitive prokaryote, and this internalized virus forming a nucleus or causing the cell to be predated by another cell. Even though there are different theories for the nucleus, we can see that the three organelles that have double membranes look like they could have been endocytosed cells, that then evolved into the organelles we see today. Endocytosis resulted in symbiosis, so the theory of organelle development is called <b>endosymbiosis</b>. </div>
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Endosymbiosis is a cool idea and has lots of support. Besides the double membrane evidence, lets look at how dividing cells get more mitochondria and chloroplasts. These organelles replicate on their own by binary fission, just like bacteria. They can replicate on their own because they have their own DNA. Mitochondrial DNA (mtDNA) and chloroplast DNA (chDNA) are smaller pieces of DNA than nuclear chromosomes, mtDNA and chDNA look much like the small genomes of bacteria. They are also circular pieces of DNA, not linear like our nuclear chromosomes.</div>
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By replicating through binary fission, they can be portioned in the dividing cell so that each daughter gets some of these crucial organelles. But it isn’t as if mitochondria and chloroplasts of today look just like the engulfed ancestors. Mitochondrial and chloroplast genomes are greatly reduced from what they used to be. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7jfqjmN0B8u1kFlPCmPzS39Ah0r9buosylVRBTdFPnB5jhg8h8yVQISjI9THEjz4sEA9WpEZNcGCzHBcuPq4epNraiAofs8o6m5emIH2wv-COikLD4Y0JheA5hFc-SdpeHMyCgWVAt5Ot/s1600/serial+endosymbiosis.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="163" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7jfqjmN0B8u1kFlPCmPzS39Ah0r9buosylVRBTdFPnB5jhg8h8yVQISjI9THEjz4sEA9WpEZNcGCzHBcuPq4epNraiAofs8o6m5emIH2wv-COikLD4Y0JheA5hFc-SdpeHMyCgWVAt5Ot/s400/serial+endosymbiosis.jpg" width="400" /></a></td></tr>
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<span style="font-size: 10pt;">Serial endocytosis is also called secondary (2˚) endocytosis.</span></div>
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<span style="font-size: 10pt;">This refers to the movement of DNA from internalized</span></div>
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<span style="font-size: 10pt;">cells to the nucleus of the endocytosing cell by lateral</span></div>
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<span style="font-size: 10pt;">gene transfer. This strengthens the symbiotic relationship</span></div>
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<span style="font-size: 10pt;">between the two organisms until they can be considered</span></div>
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<span style="font-size: 10pt;">one total organism.</span></div>
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<span style="background: none repeat scroll 0% 0% lime;"></span><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span> mitochondria only codes for about thirteen proteins, just enough for it to replicate on its own. The DNA that codes for the rest of the 1500 or so proteins needed for mitochondrial function have been transferred to the nucleus over time. For a discussion of the chloroplast and its horizontal gene transfer to the nucleus, see the posts on <a href="http://biologicalexceptions.blogspot.com/2011/08/biological-hybrids-diet-to-end-all.html"><i style="background-color: white;"><span style="-moz-background-clip: border; -moz-background-origin: padding; -moz-background-size: auto auto; background-attachment: scroll; background-image: none; background-position: 0% 0%; background-repeat: repeat;">C. litorea</span></i></a>, the photosynthetic sea slug.</div>
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We know that these gene transfers were actual events based on the structure and nucleotide ordering of the mitochondrial and photosynthetic sequences in the eukaryotic chromosomes; they are structured and coded in ways that are typically bacterial. Because of this slow transfer of DNA to the nucleus, endosymbiosis has evolved over time, changing again and again until we got today’s organelles. Therefore, our idea of organelle development is sometimes called <b>serial endosymbiosis theory</b> (SET), because it must have had several different changes through evolution.</div>
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Now that we have laid out the evidence and sense for the serial endosymbiosis theory, next week we can talk about some exceptions that show us that that some organisms just can't stick with something that seems to work. Some life just has to take the road less traveled.</div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Proceedings.+Biological+sciences+%2F+The+Royal+Society&rft_id=info%3Apmid%2F27194700&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Major+evolutionary+transitions+of+life%2C+metabolic+scaling+and+the+number+and+size+of+mitochondria+and+chloroplasts.&rft.issn=0962-8452&rft.date=2016&rft.volume=283&rft.issue=1831&rft.spage=&rft.epage=&rft.artnum=&rft.au=Okie+JG&rft.au=Smith+VH&rft.au=Martin-Cereceda+M&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CEvolutionary+Biology%2C+Biochemistry%2C+Genetics+%2C+Zoology%2C+Microbiology">Okie JG, Smith VH, & Martin-Cereceda M (2016). Major evolutionary transitions of life, metabolic scaling and the number and size of mitochondria and chloroplasts. <span style="font-style: italic;">Proceedings. Biological sciences / The Royal Society, 283</span> (1831) PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/27194700" rev="review">27194700</a></span><br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=mBio&rft_id=info%3Apmid%2F26980834&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Novel+Trypanosomatid-Bacterium+Association%3A+Evolution+of+Endosymbiosis+in+Action.&rft.issn=&rft.date=2016&rft.volume=7&rft.issue=2&rft.spage=&rft.epage=&rft.artnum=&rft.au=Kostygov+AY&rft.au=Dob%C3%A1kov%C3%A1+E&rft.au=Grybchuk-Ieremenko+A&rft.au=V%C3%A1hala+D&rft.au=Maslov+DA&rft.au=Vot%C3%BDpka+J&rft.au=Luke%C5%A1+J&rft.au=Yurchenko+V&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMicrobiology+%2C+Biochemistry%2C+Cell+Biology%2C+Zoology%2C+Reproduction%2C+Structural+Biology%2C+Evolutionary+Biology">Kostygov AY, Dobáková E, Grybchuk-Ieremenko A, Váhala D, Maslov DA, Votýpka J, Lukeš J, & Yurchenko V (2016). Novel Trypanosomatid-Bacterium Association: Evolution of Endosymbiosis in Action. <span style="font-style: italic;">mBio, 7</span> (2) PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/26980834" rev="review">26980834</a></span><br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Applied+and+environmental+microbiology&rft_id=info%3Apmid%2F24487526&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Characterization+of+a+planctomycetal+organelle%3A+a+novel+bacterial+microcompartment+for+the+aerobic+degradation+of+plant+saccharides.&rft.issn=0099-2240&rft.date=2014&rft.volume=80&rft.issue=7&rft.spage=2193&rft.epage=205&rft.artnum=&rft.au=Erbilgin+O&rft.au=McDonald+KL&rft.au=Kerfeld+CA&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CBiochemistry%2C+Botany%2C+Cell+Biology%2C+Chemical+Biology%2C+Evolutionary+Biology%2C+Microbiology+%2C+Molecular+Biology%2C+Zoology"><br /></span>
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Applied+and+environmental+microbiology&rft_id=info%3Apmid%2F24487526&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Characterization+of+a+planctomycetal+organelle%3A+a+novel+bacterial+microcompartment+for+the+aerobic+degradation+of+plant+saccharides.&rft.issn=0099-2240&rft.date=2014&rft.volume=80&rft.issue=7&rft.spage=2193&rft.epage=205&rft.artnum=&rft.au=Erbilgin+O&rft.au=McDonald+KL&rft.au=Kerfeld+CA&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CBiochemistry%2C+Botany%2C+Cell+Biology%2C+Chemical+Biology%2C+Evolutionary+Biology%2C+Microbiology+%2C+Molecular+Biology%2C+Zoology">Erbilgin O, McDonald KL, & Kerfeld CA (2014). Characterization of a planctomycetal organelle: a novel bacterial microcompartment for the aerobic degradation of plant saccharides. <span style="font-style: italic;">Applied and environmental microbiology, 80</span> (7), 2193-205 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/24487526" rev="review">24487526</a></span>
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<span style="font-size: 10pt;">For more information or classroom activities on history of life time lines, endocytosis, serial endosymbiosis theory, evolution of eukaryotes, or planctomycetes, see:</span></div>
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<span style="font-size: 10pt;">History of life on Earth timelines - </span></div>
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<span style="font-size: 10pt;"><a href="http://exploringorigins.org/timeline.html">http://exploringorigins.org/timeline.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.bbc.co.uk/nature/history_of_the_earth">http://www.bbc.co.uk/nature/history_of_the_earth</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.scientificpsychic.com/etc/timeline/timeline.html">http://www.scientificpsychic.com/etc/timeline/timeline.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lifethroughtime.com/experience.html">http://www.lifethroughtime.com/experience.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://dsc.discovery.com/earth/wide-angle/mass-extinctions-timeline.html">http://dsc.discovery.com/earth/wide-angle/mass-extinctions-timeline.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.acad.carleton.edu/curricular/BIOL/classes/bio302/pages/IntTimeline.html">http://www.acad.carleton.edu/curricular/BIOL/classes/bio302/pages/IntTimeline.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://serc.carleton.edu/quantskills/activities/calculatortape.html">http://serc.carleton.edu/quantskills/activities/calculatortape.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.mysciencebox.org/timelines">http://www.mysciencebox.org/timelines</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.saskschools.ca/.../timeline/biologicaltimeline/teachernotes.rtf"><span style="font-style: normal;">www.saskschools.ca/.../</span><b><span style="font-style: normal;">timeline</span></b><span style="font-style: normal;">/</span><b><span style="font-style: normal;">biologicaltimeline</span></b><span style="font-style: normal;">/teachernotes.rtf</span></a></span></cite></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.jessb.org/blog/.../Timeline%20description%20and%20setup.pd"><span style="font-style: normal;">www.jessb.org/blog/.../</span><b><span style="font-style: normal;">Timeline</span></b><span style="font-style: normal;">%20description%20and%20setup.pd</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.nclark.net/HistoryLife">http://www.nclark.net/HistoryLife</a></span></div>
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<span style="font-size: 10pt;"><a href="http://faculty.ccri.edu/lmfrolich/Microbiology/toilet_paper_history_of_life.htm">http://faculty.ccri.edu/lmfrolich/Microbiology/toilet_paper_history_of_life.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/evolution/library/03/index.html">http://www.pbs.org/wgbh/evolution/library/03/index.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://evolution.berkeley.edu/evolibrary/article/evo_03">http://evolution.berkeley.edu/evolibrary/article/evo_03</a></span></div>
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<span style="font-size: 10pt;">Endocytosis – </span></div>
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<span style="font-size: 10pt;"><a href="http://academic.brooklyn.cuny.edu/biology/bio4fv/page/endocyta.htm">http://academic.brooklyn.cuny.edu/biology/bio4fv/page/endocyta.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=4gLtk8Yc1Zc">http://www.youtube.com/watch?v=4gLtk8Yc1Zc</a></span></div>
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<span style="font-size: 10pt;"><a href="http://bcs.whfreeman.com/thelifewire/content/chp05/0502003.html">http://bcs.whfreeman.com/thelifewire/content/chp05/0502003.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.maxanim.com/physiology/Endocytosis%20and%20Exocytosis/Endocytosis%20and%20Exocytosis.htm">http://www.maxanim.com/physiology/Endocytosis%20and%20Exocytosis/Endocytosis%20and%20Exocytosis.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.susanahalpine.com/anim/Life/endo.htm">http://www.susanahalpine.com/anim/Life/endo.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.physorg.com/news/2011-07-endocytosis-simpler.html">http://www.physorg.com/news/2011-07-endocytosis-simpler.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lessonplanet.com/search?keywords=endocytosis+activity&media=lesson">http://www.lessonplanet.com/search?keywords=endocytosis+activity&media=lesson</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.accessexcellence.org/AE/ATG/data/released/0520-MichaelJVLazaroff/index.php">http://www.accessexcellence.org/AE/ATG/data/released/0520-MichaelJVLazaroff/index.php</a></span></div>
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<span style="font-size: 10pt;"><a href="http://peer.tamu.edu/LessonPlan.asp?id=128&file=activity">http://peer.tamu.edu/LessonPlan.asp?id=128&file=activity</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ehow.com/list_6942012_team-building-activities-science-teachers.html">http://www.ehow.com/list_6942012_team-building-activities-science-teachers.html</a></span></div>
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<br /></div>
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<span style="font-size: 10pt;">Serial endosymbiosis theory – </span></div>
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<span style="font-size: 10pt;"><a href="http://evolution.berkeley.edu/evolibrary/article/_0/endosymbiosis_01">http://evolution.berkeley.edu/evolibrary/article/_0/endosymbiosis_01</a></span></div>
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<span style="font-size: 10pt;"><a href="http://instructorexchange.pearsoncmg.com/category/activities/diversity-activities/endosymbiosis/">http://instructorexchange.pearsoncmg.com/category/activities/diversity-activities/endosymbiosis/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.biology.iupui.edu/biocourses/N100/2k2endosymb.html">http://www.biology.iupui.edu/biocourses/N100/2k2endosymb.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lessonplanet.com/search?keywords=endosymbiotic+theory&media=lesson">http://www.lessonplanet.com/search?keywords=endosymbiotic+theory&media=lesson</a></span></div>
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<span style="font-size: 10pt;"><a href="http://kenanfellows.org/kfp-cp-sites/cp20/cp20/lives-cell-lewis-thomas/index.html">http://kenanfellows.org/kfp-cp-sites/cp20/cp20/lives-cell-lewis-thomas/index.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://serialendosymbiosis.blogspot.com/2007/12/serial-endosymbiosis-theory-set.html">http://serialendosymbiosis.blogspot.com/2007/12/serial-endosymbiosis-theory-set.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lionden.com/set_and_organelles.htm">http://www.lionden.com/set_and_organelles.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://endosymbionts.blogspot.com/2006/12/serial-endosymbiosis-theory-set.html">http://endosymbionts.blogspot.com/2006/12/serial-endosymbiosis-theory-set.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://invader-xan.pbworks.com/w/page/8696780/Serial%20Endosymbiosis%20Theory">http://invader-xan.pbworks.com/w/page/8696780/Serial%20Endosymbiosis%20Theory</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.dummies.com/how-to/content/endosymbiotic-theory.html">http://www.dummies.com/how-to/content/endosymbiotic-theory.html</a></span></div>
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<span style="font-size: 10pt;"><a href="https://www.msu.edu/course/lbs/145/luckie/margulis.html">https://www.msu.edu/course/lbs/145/luckie/margulis.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.fossilmuseum.net/Evolution/Endosymbiosis.htm">http://www.fossilmuseum.net/Evolution/Endosymbiosis.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.youtube.com/watch?v=RaAM8qQcs6E">http://www.youtube.com/watch?v=RaAM8qQcs6E</a></span></div>
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<br /></div>
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<span style="font-size: 10pt;">Evolution of eukaryotes – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.infoplease.com/cig/biology/eukaryote-evolution.html">http://www.infoplease.com/cig/biology/eukaryote-evolution.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://evolution.berkeley.edu/evolibrary/article/_0/endosymbiosis_03">http://evolution.berkeley.edu/evolibrary/article/_0/endosymbiosis_03</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.bacterialphylogeny.info/eukaryotes.html">http://www.bacterialphylogeny.info/eukaryotes.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endosymbiosis.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endosymbiosis.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://anthropogeny.com/Evolution%20of%20Eukaryotes,%20Crossing%20Over%20and%20Sex.htm">http://anthropogeny.com/Evolution%20of%20Eukaryotes,%20Crossing%20Over%20and%20Sex.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.gwu.edu/~darwin/BiSc151/Eukaryotes/Eukaryotes.html">http://www.gwu.edu/~darwin/BiSc151/Eukaryotes/Eukaryotes.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.world-builders.org/lessons/less/les4/eukaryotes.html">http://www.world-builders.org/lessons/less/les4/eukaryotes.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.sumanasinc.com/webcontent/animations/content/organelles.html">http://www.sumanasinc.com/webcontent/animations/content/organelles.html</a></span></div>
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<span style="font-size: 10pt;">Planctomycetes – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/scitable/topicpage/beyond-prokaryotes-and-eukaryotes-planctomycetes-and-cell-14158971">http://www.nature.com/scitable/topicpage/beyond-prokaryotes-and-eukaryotes-planctomycetes-and-cell-14158971</a></span></div>
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<span style="font-size: 10pt;"><a href="http://en.wikipedia.org/wiki/Planctomycetes">http://en.wikipedia.org/wiki/Planctomycetes</a></span></div>
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<span style="font-size: 10pt;"><a href="http://schaechter.asmblog.org/schaechter/2007/06/planctomycetes_.html">http://schaechter.asmblog.org/schaechter/2007/06/planctomycetes_.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&ved=0CJ0BEBYwDg&url=http%3A%2F%2Fwww.nick-lane.net%2FMcInerney%20et%20al%20planctomycetes%20vs%20eukaryotes.pdf&ei=1x13T5ymN8Gtgwfrl4WiDw&usg=AFQjCNGndtkUYkLWpDshDQdQu-kfgpL91w">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&ved=0CJ0BEBYwDg&url=http%3A%2F%2Fwww.nick-lane.net%2FMcInerney%2520et%2520al%2520planctomycetes%2520vs%2520eukaryotes.pdf&ei=1x13T5ymN8Gtgwfrl4WiDw&usg=AFQjCNGndtkUYkLWpDshDQdQu-kfgpL91w</a></span></div>
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<span style="font-size: 10pt;"><a href="http://bioinf.nuim.ie/2011/10/planctomycetes-and-eukaryotes-are-both-interesting-but-not-specifically-related/">http://bioinf.nuim.ie/2011/10/planctomycetes-and-eukaryotes-are-both-interesting-but-not-specifically-related/</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com2tag:blogger.com,1999:blog-8136765635696545893.post-64637697573826221982017-11-02T06:00:00.000-04:002017-11-02T06:00:09.334-04:00Extremophiles Are Key, Or Archaea<div style="text-align: right;">
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Biology concepts – <u>archaea</u>, <u>bacteria</u>, <u>domains of life</u>, <u>hydrothermal vent ecosystem</u>, <u>chemosynthesis</u></div>
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What is a bigger mistake – to overestimate or to underestimate? If you overestimate someone, you may be disappointed with the result. If you underestimate, you may never realize what they are capable of accomplishing. What is more, your underestimation may cause you to miss incredible things already taking place.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE7R4pltDKzwtcyPcTbEuAk3Ss3b5rsj5tw_OFFiP9fUJiXCz0Clf2KMc3RTEIJAffuwzKQjlIWOBp2VbOHeqwT3QWfhKgLlQl6YXeBiFLR3QT_L2gCxlQaMCTW933OOGVpeEbrQ8o202a/s1600/1-Underestimating.JPG" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="256" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE7R4pltDKzwtcyPcTbEuAk3Ss3b5rsj5tw_OFFiP9fUJiXCz0Clf2KMc3RTEIJAffuwzKQjlIWOBp2VbOHeqwT3QWfhKgLlQl6YXeBiFLR3QT_L2gCxlQaMCTW933OOGVpeEbrQ8o202a/s320/1-Underestimating.JPG" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">Underestimate the power and importance of </span></div>
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<span style="font-size: 10pt;">wee small things at your peril. The atom holds </span></div>
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<span style="font-size: 10pt;">extreme amounts of energy, and we depend on </span></div>
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<span style="font-size: 10pt;">the tiniest of prokaryotes for our survival on Earth.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">It</span><span style="background-color: white;"> </span>would be a mistake to underestimate the grit and power of some of nature’s smallest organisms. We could talk about this for months, but why don’t we stick to the discussion of prokaryotes and their ability to get along without conventional organelles that we began last week.</div>
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We can go farther in praise of the prokaryote by looking at how some of them manage to live in the most inhospitable environments; places that would kill us in seconds, or at least we hope they would. These are the “extremophiles;” the name makes them sound like Saturday morning cartoon superheroes. For example, <i>Thermococcus gammatolerans</i> is the most radiation tolerant organism on Earth. It can laugh at gamma radiation levels 100x higher than other resistant organisms, even though it lives at the bottom of the sea.</div>
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As a result of the molecular biology revolution, many of the extremophiles are now called <b>Archaea</b> (Greek for “ancient”) or archaeabacteria, a completely group of organisms. Archaea are older than bacteria, and but they have some similarities to bacteria. Archaea are generally smaller than bacteria, but the cell wall of most archaea looks just like that of Gram<sup>+</sup> bacteria. This is a thicker cell wall than that of Gram<sup>-</sup> bacteria, and takes up the Gram stain, hence the name Gram<sup>+</sup>. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhi-8_926Blsqb1eW5DeofpSVmAUbvCjX1ryzw-UFqe9kELMV-WgOKTuzMua24jvmpPCqqg9Bx6gm7gPyRAHO9jAkXF-l1Fe4jTDIJbjHw4zz4_g3CNeXBHS4i4w10OdK4-5Gf3IZx6y9WT/s1600/2-archaea+wall.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="135" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhi-8_926Blsqb1eW5DeofpSVmAUbvCjX1ryzw-UFqe9kELMV-WgOKTuzMua24jvmpPCqqg9Bx6gm7gPyRAHO9jAkXF-l1Fe4jTDIJbjHw4zz4_g3CNeXBHS4i4w10OdK4-5Gf3IZx6y9WT/s400/2-archaea+wall.jpg" width="400" /></a></td></tr>
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<span style="font-size: 10pt;">The archaea cell wall is thick, and is contiguous with the cell membrane, </span></div>
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<span style="font-size: 10pt;">like that of Gram<sup>+</sup> bacteria. Gram<sup>-</sup> bacteria have thinner walls and </span></div>
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<span style="font-size: 10pt;">they have a periplasmic space between the wall and the membrane.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Just</span> looking at archaea and bacteria through a microscope makes it hard to tell the difference between these two distant relatives. It is at the molecular level that most of their differences become apparent. The way that archaea make RNAs is more eukaryotic than bacterial and while they both have cell walls, the lipids that make up archaeal membranes are quite different. Archaea lipids are hydrocarbon based, not fatty acid based like those of eukaryotes and bacteria. Also, archaeal cell walls lack the peptidoglycan that is characteristic of bacterial cell walls. Peptidoglycan synthesis is a common target of antibiotics, like penicillins, cephalosporines, and vancomycin.</div>
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This last difference might work out O.K. for us as humans. Not a single disease can be attributed to an archaea – yet. This is a big exception. Every other group of organisms on Earth has at least some members that can do humans harm, even if only inadvertently. Fungi, protozoa, bacteria, even plants can all cause us harm. One study says it is unlikely that we have just missed disease-causing archaea. About 0.38% of bacterial species cause disease, so if diversity in archaea is similar to that in bacteria, we should have found about 20 disease causing archaea by now. </div>
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Gum disease (periodontitis) has an outside chance of having an archaeal cause, but the evidence is sketchy. In a couple of studies, the presence of archaea in the mouth has correlated with gum disease; if archaea were present, then there was disease. Also, higher archaea number correlated to more severe disease. But archaea were only present in 1/3 of all cases of periodontitis – this is not good evidence to say archaea are the cause of periodontitis. This is the closest we have come to finding an archaeon with an anti-human bent. </div>
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Some archaea are <b>thermophiles</b> (heat loving); they don’t just like it hot, some require it really hot. Many thermophiles live in near undersea hydrothermal vents, where heat from the Earth’s mantle and core escapes into the ocean; basically ocean volcanoes.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOdlbtcA_iPB3O5PMM6-KlSkxoqsBjstoW8Ih29LOtsbbKQ9eRemWuPFT29fi3t3FDnAFt_BOv0R46YWNtRfJOOgc0Pi3SwsR7c5jI2t-N74qlja5WRCwWpLKuAdhb2QbLjrOEQ6v-oB2U/s1600/3-hydrothermal-vent.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="257" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOdlbtcA_iPB3O5PMM6-KlSkxoqsBjstoW8Ih29LOtsbbKQ9eRemWuPFT29fi3t3FDnAFt_BOv0R46YWNtRfJOOgc0Pi3SwsR7c5jI2t-N74qlja5WRCwWpLKuAdhb2QbLjrOEQ6v-oB2U/s400/3-hydrothermal-vent.jpg" width="400" /></a></td></tr>
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<span style="font-size: 10pt;">The hydrothermal vent is an ecosystem that one</span></div>
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<span style="font-size: 10pt;">would be hard pressed to call home. Varies from 700˚C</span></div>
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<span style="font-size: 10pt;">to 4˚C, it is acidic, toxic, and radioactive. Yet many unique</span></div>
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<span style="font-size: 10pt;">prokaryotic and eukaryotic organisms live nowhere else.</span></div>
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<span style="font-size: 10pt;">To each his own.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Near</span> a thermal vent, the temperature can reach 400-410˚C (700-720˚F) . The water doesn’t boil because of the great pressure exerted on it by all the water above it. No eukaryotic organism can survive at these temperatures, but thermophiles like <i>T. gammatolerans</i> do just fine. The hydrothermal vents pour out high levels of gamma type ionizing radiation from deep in the Earth, so it is handy that this archaeon is a multi-extremophile.</div>
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Only a few feet away from the vent the temperature of the ocean bottom will remain near freezing, about 4.5˚C. Other archaea (and some true bacteria) thrive in this cold environment. Called <b>psychrophiles</b>, cold tolerant archaea have cell walls that resist stiffening in water that is even below freezing temperature, and can fill there cytoplasm with <b>anti-freeze proteins</b> (AFPs; they create a difference between a solution melting point and its freezing point, called <b>thermal hysteresis</b>).</div>
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Between these two extreme environments, you can find quasi-conventional animals. As the hydrothermal vent water gives up its heat to the surrounding ocean, it creates an area that holds a temperature of about 10-15˚C. Many interesting animals have been found in this area, including the yeti crab and tube worms. <a href="http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001234">Data from January 2012</a> describes a pure white octopus found at a depth of 2,394 meters. At this depth there is no light, so the octopus has no need for the elaborate camouflage mechanisms of color and texture. This octopod may represent a new species, but other white, vent-dwelling octopuses have been described previously, just not this far south. </div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7SmKkR5yioVTwD_Aw86jG8O_OTq5pm_G0rdW0eIawA_aTegSqr0cF-DrL1HS6FF9D54yO_rWaSGOUmXDQhyg3xzTfEgu496TgzuPN22SYd3qA1mDiKthaA-PzE51bD1Pr8E4dl5iN04lU/s1600/4-yeti_crab.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="182" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7SmKkR5yioVTwD_Aw86jG8O_OTq5pm_G0rdW0eIawA_aTegSqr0cF-DrL1HS6FF9D54yO_rWaSGOUmXDQhyg3xzTfEgu496TgzuPN22SYd3qA1mDiKthaA-PzE51bD1Pr8E4dl5iN04lU/s320/4-yeti_crab.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">This is the yeti crab (<i>Kiwa hirsute</i>). It is white because it lives </span></div>
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<span style="font-size: 10pt;">in the dark. It is furry because……..well, it makes the name </span></div>
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<span style="font-size: 10pt;">appropriate. Actually, the setae (hairs) contain bacteria that</span></div>
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<span style="font-size: 10pt;">may act to detoxify the water from the hydrothermal vents</span></div>
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<span style="font-size: 10pt;">where it lives. And it isn’t really a crab either, but I’m not</span></div>
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<span style="font-size: 10pt;">going to tell it so.</span></div>
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Ultimately, even these animals depend on the archaea for survival. No photosynthetic producers can survive at these depths, so the food chain starts with the <a href="http://biologicalexceptions.blogspot.com/2012/03/simple-aint-so-simple-anymore.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">chemosynthesizing</span></a> prokaryotes, particularly those that use hydrogen sulfide to produce energy. Hydrogen sulfide is a major constituent in the hydrothermal vent output…. and would kill us quickly by binding to the enzymes in our mitochondria that perform ATP synthesis.</div>
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Some animals, like snails, eat the chemosynthesizing prokaryotes directly, while others predate the snails, etc. On the other hand, tube worms (<span class="st"><i>Riftia pachyptila</i>)</span> get their energy directly from thermophilic proteobacterium that live inside the worm in a symbiotic relationship.</div>
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Other archaea live in high salt environments, like in the Dead Sea or the Great Salt Lake. They must be lonely, because given the high salinity, they are the only things living there (<a href="http://biologicalexceptions.blogspot.com/2012/02/water-water-everywhere-but.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Water, Water Everywhere, But….</span></a>). On the grosser end of the scale, some archaea thrive in human sewage plants, working well in environments without oxygen and high nitrogen contents.</div>
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Archaea have also been found in natural asphalt lakes, like near the La Brea region of Trinidad and Tobago. With toxic gases, high temperature, and practically no water at all, it was surprising that scientists found so many different kinds of prokaryotes, including several types of archaea. These 2010 findings suggest that life on other planets might not necessarily depend on water – that would be one heck of an exception!</div>
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But not all archaea are extremophiles, and they turn out to be much more common than we had thought. This isn’t just a numbers game, it turns out that we have been underestimating their effects on our lives all along. For instance, nitrogen fixation is crucial for crop production. A 2006 study by Schleper et al. in Norway suggests that there are many more ammonia oxidizing archaea in the soil than there are nitrogen fixing bacteria. </div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-TNub04WJJHYvbkNuAY9mYXUY5hBPULE4TXGpKfs-lO0JKugZwqU3JeUCGtgb3ctDLJ-S7Kj9ShsAwFkIc_XB-X0G-pLKxkwsuH5bRO_eqsEhYfItqPaE-ueH5NTCWPv0PDZPSixMwxbJ/s1600/5-primary+production.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-TNub04WJJHYvbkNuAY9mYXUY5hBPULE4TXGpKfs-lO0JKugZwqU3JeUCGtgb3ctDLJ-S7Kj9ShsAwFkIc_XB-X0G-pLKxkwsuH5bRO_eqsEhYfItqPaE-ueH5NTCWPv0PDZPSixMwxbJ/s400/5-primary+production.jpg" width="400" /></a></td></tr>
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<span style="font-size: 10pt;">Archaea are responsible for much of the primary production that </span></div>
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<span style="font-size: 10pt;">occurs in the soil and in the water. Just the methanogenic </span></div>
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<span style="font-size: 10pt;">archaea alone are responsible for nearly 2% of all the carbohydrates </span></div>
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<span style="font-size: 10pt;">produced on Earth. Archaea contribute to the primary production </span></div>
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<span style="font-size: 10pt;">of every ecosytem.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Further</span>, current evidence suggests that archaea may represent 25-84% of all <b>primary production</b> (creation of carbohydrates and other organic compounds from inorganic carbon sources, whether by photosynthesis or chemosynthesis) in the upper layers of seawater. Primary production is the beginning of every food chain, so ultimately all of our food depends on archaea as well. To bad that we have been underestimating our dependence on these oldest of life forms. Who knows what our effects our life choices have been having on them all these years.</div>
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On the other hand, not all extremophiles are archaea either. <i>Thermus aquaticus</i> is a bacterium that lives in hot sulfur springs and geysers. It is a chemosynthesizing bacterium that has become important in molecular biology. Since its enzymes can tolerate high temperatures, it is useful for replicating DNA sequences in the lab using the <b>polymerase chain reaction</b>. One step in this reaction requires high temperature and would kill most other enzymes. </div>
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Amazingly, this PCR technology and <i>T. aquaticus </i>polymerase has been crucial for helping us see how important the archaea have been in our evolution. In 1977, scientists Carl Woese and George Fox began DNA sequencing of some the extremophiles. They recognized that archaea were very different from eubacteria. The two groups must have diverged long long ago. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkIQ4_GWhukytls0-w2ROSZz231Kv0COeOrDqJZ5gn1Rj3-yQGgJZoSQIYWQlccoyQnVTBgZfjEdHEFFrDdedJbBaXP1YNARVdVw-lBj8X2y0zSEYg8LTdWBt6xKJ7-6W-kcRqBdLiMMEm/s1600/6-threedomains.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="357" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkIQ4_GWhukytls0-w2ROSZz231Kv0COeOrDqJZ5gn1Rj3-yQGgJZoSQIYWQlccoyQnVTBgZfjEdHEFFrDdedJbBaXP1YNARVdVw-lBj8X2y0zSEYg8LTdWBt6xKJ7-6W-kcRqBdLiMMEm/s400/6-threedomains.gif" width="400" /></a></td></tr>
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<span style="font-size: 10pt;">The three domains of life are shown here. The length of line shows </span></div>
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<span style="font-size: 10pt;">the evolutionary distance between domains. You can see that </span></div>
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<span style="font-size: 10pt;">Archaea are more like us than are the bacteria. You can’t tell from </span></div>
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<span style="font-size: 10pt;">this chart, but Archaea are older too. They are the roots</span></div>
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<span style="font-size: 10pt;">of our family tree.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">It</span> turns out that Archaea are as closely related to eukaryotes as they are to eubacteria. This stood science on its ear. Up to this point, scientists had been arguing as to whether there were four, or five, or six kingdoms. Now they had to impose a higher classification which superseded all the kingdoms.</div>
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Woese’s evidence has led us define to the three domains of life. One domain is the eukaroytes, all the cells with a nucleus (with exceptions, but we can talk about those later), with linear chromosomes instead of one circular piece of DNA (again with exceptions), and with organelles. The second domain is the archaea and the third domain is the bacteria. Six kingdoms follow from these domains; archaea, bacteria, protista, fungi, plantae, and animalia.</div>
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Archaea, bacteria, and eukaryotes; we have shown that they are all different, and yet they all developed from some single precursor cell. Next time we will see if our discussion to this point gives us a roadmap to get from that ancient first cell to us.</div>
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<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=PLoS+Biology&rft_id=info%3Adoi%2F10.1371%2Fjournal.pbio.1001234&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=The+Discovery+of+New+Deep-Sea+Hydrothermal+Vent+Communities+in+the+Southern+Ocean+and+Implications+for+Biogeography&rft.issn=1545-7885&rft.date=2012&rft.volume=10&rft.issue=1&rft.spage=0&rft.epage=&rft.artnum=http%3A%2F%2Fdx.plos.org%2F10.1371%2Fjournal.pbio.1001234&rft.au=Rogers%2C+A.&rft.au=Tyler%2C+P.&rft.au=Connelly%2C+D.&rft.au=Copley%2C+J.&rft.au=James%2C+R.&rft.au=Larter%2C+R.&rft.au=Linse%2C+K.&rft.au=Mills%2C+R.&rft.au=Garabato%2C+A.&rft.au=Pancost%2C+R.&rft.au=Pearce%2C+D.&rft.au=Polunin%2C+N.&rft.au=German%2C+C.&rft.au=Shank%2C+T.&rft.au=Boersch-Supan%2C+P.&rft.au=Alker%2C+B.&rft.au=Aquilina%2C+A.&rft.au=Bennett%2C+S.&rft.au=Clarke%2C+A.&rft.au=Dinley%2C+R.&rft.au=Graham%2C+A.&rft.au=Green%2C+D.&rft.au=Hawkes%2C+J.&rft.au=Hepburn%2C+L.&rft.au=Hilario%2C+A.&rft.au=Huvenne%2C+V.&rft.au=Marsh%2C+L.&rft.au=Ramirez-Llodra%2C+E.&rft.au=Reid%2C+W.&rft.au=Roterman%2C+C.&rft.au=Sweeting%2C+C.&rft.au=Thatje%2C+S.&rft.au=Zwirglmaier%2C+K.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CAnatomy%2C+Cell+Biology%2C+Microbiology+%2C+Evolutionary+Biology%2C+Zoology">Rogers, A., Tyler, P., Connelly, D., Copley, J., James, R., Larter, R., Linse, K., Mills, R., Garabato, A., Pancost, R., Pearce, D., Polunin, N., German, C., Shank, T., Boersch-Supan, P., Alker, B., Aquilina, A., Bennett, S., Clarke, A., Dinley, R., Graham, A., Green, D., Hawkes, J., Hepburn, L., Hilario, A., Huvenne, V., Marsh, L., Ramirez-Llodra, E., Reid, W., Roterman, C., Sweeting, C., Thatje, S., & Zwirglmaier, K. (2012). The Discovery of New Deep-Sea Hydrothermal Vent Communities in the Southern Ocean and Implications for Biogeography <span style="font-style: italic;">PLoS Biology, 10</span> (1) DOI: <a href="http://dx.doi.org/10.1371/journal.pbio.1001234" rev="review">10.1371/journal.pbio.1001234</a></span>
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<span style="font-size: 10pt;">For more information and classroom activities on archaea, hydrothermal vents, chemosynthesis, and domain/kingdoms, see:</span></div>
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<br /></div>
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<span style="font-size: 10pt;">Archaea and extremophile bacteria – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.ucmp.berkeley.edu/archaea/archaea.html">http://www.ucmp.berkeley.edu/archaea/archaea.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lessonsnips.com/lesson/extremophile">http://www.lessonsnips.com/lesson/extremophile</a></span></div>
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<span style="font-size: 10pt;"><a href="http://euarch.blogspot.com/">http://euarch.blogspot.com/</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.sinauer.com/pdf/Staley2e_Ch17.pdf"><span style="font-style: normal;">www.sinauer.com/pdf/Staley2e_Ch17.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.windows2universe.org/earth/Life/archaea.html">http://www.windows2universe.org/earth/Life/archaea.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Archaea.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Archaea.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ucmp.berkeley.edu/archaea/archaeamm.html">http://www.ucmp.berkeley.edu/archaea/archaeamm.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://serc.carleton.edu/microbelife/extreme/extremophiles.html">http://serc.carleton.edu/microbelife/extreme/extremophiles.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://science.nasa.gov/science-news/science-at-nasa/2008/07feb_cloroxlake/">http://science.nasa.gov/science-news/science-at-nasa/2008/07feb_cloroxlake/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.bath.ac.uk/cer/">http://www.bath.ac.uk/cer/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.physorg.com/news203835088.html">http://www.physorg.com/news203835088.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.eoearth.org/article/Extremophile?topic=74530">http://www.eoearth.org/article/Extremophile?topic=74530</a></span></div>
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<span style="font-size: 10pt;"><a href="http://baliga.systemsbiology.net/drupal/education/?q=content/lesson-3-introduction-extremophiles">http://baliga.systemsbiology.net/drupal/education/?q=content/lesson-3-introduction-extremophiles</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lpi.usra.edu/education/fieldtrips/2007/activities/">http://www.lpi.usra.edu/education/fieldtrips/2007/activities/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.lpi.usra.edu/education/fieldtrips/2007/resources.shtml">http://www.lpi.usra.edu/education/fieldtrips/2007/resources.shtml</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/nova/nature/lives-of-extremophiles.html">http://www.pbs.org/wgbh/nova/nature/lives-of-extremophiles.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.tes.co.uk/teaching-resource/Extremophile-lesson-6069543/">http://www.tes.co.uk/teaching-resource/Extremophile-lesson-6069543/</a></span></div>
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<span style="font-size: 10pt;">Hydrothermal vents – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.dlese.org/library/query.do?q=hydrothermal%20vents&s=0&setVocabState=re&setVocabState=gr&setVocabState=ky&setVocabState=cs&setVocabState=su&gr=&re=&cs=&ky=&su">http://www.dlese.org/library/query.do?q=hydrothermal%20vents&s=0&setVocabState=re&setVocabState=gr&setVocabState=ky&setVocabState=cs&setVocabState=su&gr=&re=&cs=&ky=&su</a>=</span></div>
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<span style="font-size: 10pt;"><a href="http://www2.vims.edu/bridge/search/bridge1output_menu.cfm?q=expedition">http://www2.vims.edu/bridge/search/bridge1output_menu.cfm?q=expedition</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.pbs.org/wgbh/nova/teachers/activities/2609_abyss.html">http://www.pbs.org/wgbh/nova/teachers/activities/2609_abyss.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://oceanexplorer.noaa.gov/explorations/06fire/background/edu/lessonplans.html">http://oceanexplorer.noaa.gov/explorations/06fire/background/edu/lessonplans.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.thirteen.org/edonline/ntti/resources/lessons/s_dive/index.html">http://www.thirteen.org/edonline/ntti/resources/lessons/s_dive/index.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nationalgeographic.com/xpeditions/lessons/07/g35/seasvents.html">http://www.nationalgeographic.com/xpeditions/lessons/07/g35/seasvents.html</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.msc.ucla.edu/oceanglobe/pdf/Deep.../Deep_6_Vent_Web.pdf"><span style="font-style: normal;">www.msc.ucla.edu/oceanglobe/pdf/Deep.../Deep_6_</span><b><span style="font-style: normal;">Vent</span></b><span style="font-style: normal;">_Web.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.montereyinstitute.org/noaa/lesson05.html">http://www.montereyinstitute.org/noaa/lesson05.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.botos.com/marine/vents01.html">http://www.botos.com/marine/vents01.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://2011.polarhusky.com/logistics/oceans/geology/hydrothermal-vents/">http://2011.polarhusky.com/logistics/oceans/geology/hydrothermal-vents/</a></span></div>
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<span style="font-size: 10pt;">Chemosynthesis – </span></div>
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<span style="font-size: 10pt;"><a href="http://2011.polarhusky.com/logistics/oceans/geology/hydrothermal-vents/">http://2011.polarhusky.com/logistics/oceans/geology/hydrothermal-vents/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ceoe.udel.edu/deepsea/level-2/chemistry/chemo.html">http://www.ceoe.udel.edu/deepsea/level-2/chemistry/chemo.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.divediscover.whoi.edu/vents/light.html">http://www.divediscover.whoi.edu/vents/light.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.montereyinstitute.org/noaa/lesson05.html">http://www.montereyinstitute.org/noaa/lesson05.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.bigelow.org/foodweb/chain4.html">http://www.bigelow.org/foodweb/chain4.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://oceanexplorer.noaa.gov/edu/learning/player/lesson05/l5ex1.htm">http://oceanexplorer.noaa.gov/edu/learning/player/lesson05/l5ex1.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ehow.com/info_8060311_primary-production-activities.html">http://www.ehow.com/info_8060311_primary-production-activities.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.thegateway.org/browse/38643">http://www.thegateway.org/browse/38643</a></span></div>
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<span style="font-size: 10pt;"><a href="http://serc.carleton.edu/sp/erese/activities/carbon-cycle-femo.html">http://serc.carleton.edu/sp/erese/activities/carbon-cycle-femo.html</a></span></div>
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<span style="font-size: 10pt;">Domains/kingdoms - </span></div>
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<span style="font-size: 10pt;"><a href="http://biology.about.com/od/evolution/a/aa041708a.htm">http://biology.about.com/od/evolution/a/aa041708a.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://faculty.plattsburgh.edu/neil.buckley/concepts%20in%20biology/lecture6domainsandkingdoms.htm">http://faculty.plattsburgh.edu/neil.buckley/concepts%20in%20biology/lecture6domainsandkingdoms.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.fossilmall.com/Science/Domains.htm">http://www.fossilmall.com/Science/Domains.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ucmp.berkeley.edu/alllife/threedomains.html">http://www.ucmp.berkeley.edu/alllife/threedomains.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://sciencespot.net/Pages/kdzbioclass.html">http://sciencespot.net/Pages/kdzbioclass.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.kidsbiology.com/biology_basics/classification/classification1.php">http://www.kidsbiology.com/biology_basics/classification/classification1.php</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.wisegeek.com/what-is-biological-classification.htm">http://www.wisegeek.com/what-is-biological-classification.htm</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.lessonsnips.com/docs/pdf/taxonomy.pdf"><span style="font-style: normal;">www.lessonsnips.com/docs/pdf/taxonomy.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www.windows2universe.org/earth/Life/classification_intro.html">http://www.windows2universe.org/earth/Life/classification_intro.html</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1tag:blogger.com,1999:blog-8136765635696545893.post-62637031553994368772017-10-26T06:00:00.000-04:002017-10-26T06:00:08.665-04:00Simple Ain’t So Simple Anymore<div class="MsoNormal">
Biology Concepts – <u>prokaryotes</u>, <u>simplicity</u>, <u>complexity</u>, <u>organelles</u>, <u>microcompartments</u></div>
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<span style="font-size: 10pt;">Not everything new is better; new doesn’t </span></div>
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<span style="font-size: 10pt;">necessarily mean improved. Remember the <br />
“New” Coke debacle?</span></div>
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Newer is better, right? Everything old is simple and plain. Back in the good old days, you had to read a book, but today you can browse the internet and pick from 8000 songs while you drive to the superstore to pick up a Kindle. Today is faster. Better. More complex?</div>
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How about living in 1800. Could you catch and kill your dinner with a trap of your own making, followed by gutting and dressing it on the back porch of a house you built with your own hands, while you try to keep your entire family from being eaten or dying from an infected scratch? Now whose world seems complex!</div>
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This same belief has been applied to forms of life. Bacteria are old and simple; we are new and complex. Plants and animals can do millions of things that bacteria can’t, because they are so simple and primitive and we are so high tech, biologically speaking.</div>
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But it is a mistake to call bacteria simple or primitive. They may not have all the bells and whistles that <b>eukaryotic</b> (eu - true and karyo = nucleus) cells have, but they have survived much longer than other life forms, and they outnumber us by billions. There are more bacteria in a handful of rich soil than people who have ever lived on Earth. So don’t confuse complexity with success. </div>
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A cursory look at bacteria would suggest that they are indeed simple. They are bags of chemicals, without the complex organelles that mark eukaryotic cells. Plus, they're small; the whole organism is just one cell. They have just one chromosome and fewer genes than eukaryotic cells. It would be easy to see them as simple. </div>
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Even at the biochemical level <b>prokaryotes</b> (pro = primitive) appear simple compared to eukaryotic cells. Our more modern cells aren’t satisfied with just making more proteins, they also modify many of these proteins, adding carbohydrates, acetyl groups, phosphate groups, sulfur groups, etc. These <b>post-translational modifications</b> (after peptides are translated from mRNA messages) are crucial for different functions and for interactions with messengers and DNA. </div>
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<span style="font-size: 10pt;">Histones are protein complexes that help DNA to coil up into tight </span><br />
<span style="font-size: 10pt;">configurations. But DNA it is tightly packaged, it is hard for </span><br />
<span style="font-size: 10pt;">individual genes to be transcribed and made into protein. Histone </span><br />
<span style="font-size: 10pt;">acetyltransferases are enzymes that add acetyl groups to the histones </span><br />
<span style="font-size: 10pt;">and open DNA to be read. Histone deacteylases do the </span><br />
<span style="font-family: "cambria"; font-size: 10pt;">opposite, they add acetyl groups and cause the DNA </span><br />
<span style="font-family: "cambria"; font-size: 10pt;">to tightly coil.</span> </div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span> exception here is that less than a decade ago scientists found that many prokaryotes also do some kinds of post-translational modifications, includingphosphorylation and acetylation. Acetylation, the addition of a -COCH<sub>3</sub> group to a molecule, is important in eukaryotic cells for several reasons, not the least of which is in determining which DNA is open to be replicated or <b>transcribed</b> (copied to mRNA). </div>
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Data from 2004 was the first to show that prokaryotes can carry out phosphorylation (addition of PO<sub>3</sub> groups) to proteins. What is more, acetylation and phosphorylation are reversible modifications, so an additional layer of complexity is added. Prokaryotic proteins have one function when modified and another when not modified, just like modification of eukaryotic proteins. Sounds like prokaryotes have more going on than we thought.</div>
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Prokaryotes are the real success stories of life on Earth. They can do things some things eukaryotes can’t do (more on this next time). Even more amazing, every deficit we have said they have - they can’t do this, they don’t have those – can be seen as a reason they are more amazing. </div>
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Prokaryotes are single celled organisms, so they have less specialization. But this means that the cell has to carry out every function that the organism needs. Could your fat cells produce antibodies and kill off protozoan invaders? I think not. We also poke fun at prokaryotes because they don’t have organelles; but this means they have to find a way to do all their chemistry in one big open environment, much more difficult .……….or maybe not. </div>
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That classic rule of biology, "eukaryotic cells have organelles and prokaryotic cells don’t," may not be completely true. This would be a big exception. Evidence shows that many kinds of prokaryotes do have local environments, called <b>microcompartments</b>. We have all been living a lie!</div>
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The most studied of the microcompartments is the <b>carboxysome</b>. This hollow shell, first described as far back as 1956, holds enzymes (RuBisCo, see <a href="http://biologicalexceptions.blogspot.com/2011/08/when-amazing-isnt-enough-sea-slug.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">When Amazing Isn’t Enough</span></a>) that many prokaryotes use for <b>carbon fixation</b>. Photosynthesis is the most obvious type of carbon fixation, where carbon in a gas form (CO<sub>2</sub>) is converted to carbon in an organic, solid form (carbohydrates). </div>
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<span style="font-size: 10pt;">Carboxysomes as seen by electron microscopy. They really</span></div>
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<span style="font-size: 10pt;">do look geometric. The faces and corners are specific groups </span></div>
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<span style="font-size: 10pt;">of proteins, and hold the enzymes inside the microcompartment. </span></div>
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<span style="font-size: 10pt;">There are minute pores where the proteins come together </span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">RuBisCo</span> is a fairly inefficient enzyme, so sequestering it with its substrate inside a microcompartment works to increase the production of energy. Doesn’t this sound a lot like one of the key reasons for the development of organelles – the bringing together of reagents for increased efficiency of reactions? </div>
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But it is not just photosynthetic bacteria (cyanobacteria) that use carboxysomes. Many other <b>autotrophic</b> bacteria (auto = own and troph = food) use carboxysomes to fix carbon during <b>chemosynthesis</b>. Chemoautotrophs, for instance, are organisms that use chemical energy rather than sunlight energy to fix carbon. </div>
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In many prokaryotes, the oxidation of hydrogen sulfide or ammonia (a nitrogen containing compound) provides the energy for producing organic carbon; <i>Thiomargarita namibinesis</i> from our posts on <a href="http://biologicalexceptions.blogspot.com/2011/08/breaking-size-barrier-giant-bacteria.html" style="background-color: white;"><span style="-moz-background-clip: border; -moz-background-origin: padding; -moz-background-size: auto auto; background-attachment: scroll; background-image: none; background-position: 0% 0%; background-repeat: repeat;">giant bacteria</span></a> uses sulfur for chemosynthesis. But there are also organisms that use the energy from the production of methane to drive carbon fixation. You have undoubtedly had experience with intestinal prokaryotes that produce methane gas (methanogens) – don’t try to say you haven’t.</div>
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The carboxysome (as a model of many microcompartments) is not a membrane bound bag as organelles are in eukaryotes. Carboxysomes are more like soccer balls made of protein, but in this case they hold a rigid polyhedral form and don’t get bicycle kicked into a prokaryotic net by Pele. </div>
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Each face of the shell is made up of a two dimensional polymer of protein hexagons. However, as architects will tell you, this is a difficult shape to close using only hexagons, even with 10,000 of them, like the typical carboxysome has. Soccer balls and the dome at the Epcot Center use strategically placed pentagonal faces that allow for the turning of the hexagonal faces and a closing of the compartment (see cartoon above). </div>
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<span style="font-size: 10pt;">These are cartoons showing the structure of a</span></div>
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<span style="font-size: 10pt;">carbon fullerene (right) and a carbon nanotube</span></div>
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<span style="font-size: 10pt;">(left). Each green sphere represents a carbon atom.</span></div>
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<span style="font-size: 10pt;">These structures are very strong, like for making </span></div>
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<span style="font-size: 10pt;">bicycle helmets. They may also become useful for</span></div>
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<span style="font-size: 10pt;">things like space elevators, nanoelectrical circuits, </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">and solid lubricants.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">We have</span> used this hexagonal and pentagonal combination for decades, but it was identified in bacteria less than five years ago. This arrangement is also seen in viral protein coats, as well as in carbon <b>fullerenes</b>, which are superstable carbon nanostructures described in 1985 and named for the inventor of the geodesic dome, Buckminster Fuller. </div>
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Could this be the exception – nature stealing an idea from humans? Probably not, I’m guessing Dr. Fuller independently happened upon the same solution that nature had worked out millions of years ago – but it took a heck of an intellect to recognize a good thing. </div>
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It might be lucky for us that Fuller’s domes had us looking for this combination in other areas. Carboxysomes are present in up to 25% prokaryotic <b>pathogens</b> (disease causing organisms), and current research is aiming to disrupt the formation of the hexagonal/pentagonal compartments as a way to kill, or at least slow down, the microbes. So many prokaryotic pathogens are developing resistance to traditional antibiotics that a new approach will be heartily welcomed.</div>
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There are other microcompartments besides the carboxysome. The bacterium <i>Clostridium kluyveri</i> is proposed to have a <b>metabolosome</b> compartment for the conversion of ethanol into carbohydrates. Furthermore, <i>Salmonella enterica</i>, is capable of producing two different metabolosomes; one for propane-1,2-diol and one for ethanolamine, for conversion of these substrates into energy-containing carbon sources.<br />
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The evidence of these additional microcompartments makes one wonder just how many different species of protein shelled microcompartments there may be. To investigate this question, a group from UCLA recently published a study using comparative genomics (comparing genes of similar and dissimilar organisms to find groups of genes of similar function) to point out possible enzyme pathways that may be sequestered in microcompartments.<br />
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<a href="http://onlinelibrary.wiley.com/doi/10.1002/pro.2196/abstract?systemMessage=Wiley+Online+Library+will+be+disrupted+on+15+December+from+10%3A00-13%3A00+GMT+%2805%3A00-08%3A00+EST%29+for+essential+maintenance">Their late 2012 study</a> suggests that new types of microcompartments for different types of propanediol metabolism, and the identification of microcompartments in organisms for which they were previously unknown, like mycobacteria. The genomic evidence also suggests new types of protein shells, differing compartments being used for differing variants of enzyme function.</div>
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It is in these final examples that we see a more concrete purpose for the microcompartment. During the metabolism of alcohol, propane-1,2-diol, or ethanolamine, a compound called acetaldehyde is formed. This is a toxic product that needs to be converted to acetic acid in rapid order to avoid toxicity to the cell. By isolating the acetaldehyde in the metabolosome, <i>S. enterica</i> improves its own living conditions. This is also important to us humans. </div>
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<span style="font-size: 10pt;">This is not a before and after picture for an embarrassing</span></div>
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<span style="font-size: 10pt;">karaoke incident. This is a demonstration of the facial </span></div>
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<span style="font-size: 10pt;">flushing reaction when a person has an ALDH2 mutation, and </span><br />
<span style="font-size: 10pt;">can’t metabolize alcohol efficiently.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Many</span> Asians and Ashkenazi Jews have a mutation of the acetaldehyde dehydrogenase (ALDH<sub>2</sub>) gene that produces the enzyme that rids the body of acetaldehyde after the consumption of alcohol. The mutation produces a poorly functioning enzyme, so acetaldehyde builds up in their systems and causes a facial flushing reaction. If both ALDH<sub>2</sub> genes (one from mom, one from dad) are mutated, the person gets violently ill from consuming ethanol. As you might imagine, populations in which this mutation is prevalent have very low rates of alcoholism.</div>
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So we have the exception that prokaryotes are not really without organelles; theirs just look different. Could you guess that the exception goes the other way too? Well, it does. The nucleus of eukaryotic cells works with microcompartments that allow certain things in and out, but keep your DNA inside the nucleus. </div>
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The pores of the nucleus <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">(<a href="http://biologicalexceptions.blogspot.com/2012/03/cells-are-great-multitaskers.html">Cells Are Great Multitaskers</a>) </span>are complex openings made up of many proteins. Why? Nuclei could just use receptors to allows certain things in or out, similar to the system used by the cell plasma membrane. But evolution went with a more complex solution.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjo68oolUdNgN5RD7EZNPyE9T_fRXWtzJsg-HAYyutPdZMlKetk2-bpVAMOFE0s5CGmhb2PKoJwGbLBMGaE9L-alHp-6YVmK2a_ipncY2KMKlYroC3oDbt80v_fHE3CwOVQ8T4FKjDRFfTc/s1600/6-vault_jmol.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjo68oolUdNgN5RD7EZNPyE9T_fRXWtzJsg-HAYyutPdZMlKetk2-bpVAMOFE0s5CGmhb2PKoJwGbLBMGaE9L-alHp-6YVmK2a_ipncY2KMKlYroC3oDbt80v_fHE3CwOVQ8T4FKjDRFfTc/s320/6-vault_jmol.jpg" width="319" /></a></td></tr>
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<span style="font-size: 10pt;">The vault complex is made of 78 identical protein chains.</span></div>
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<span style="font-size: 10pt;">One chain is shown in white. Together, they form a</span></div>
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<span style="font-size: 10pt;">microcompartment that is crucial for our nucleus function.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">There</span> is a protein microcompartment called a <b>vault complex</b> that works with the pore complex. This is a highly regulated way of moving RNAs and ribosomes (made in the nucleolus which is inside the nucleus) out of the nucleus, while keeping your DNA inside. I don’t think it is a hard concept to grasp that you cells are happier when your DNA stays inside the nucleus; do you keep your valuables on your front lawn?</div>
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Next time we will see how the nucleus, its pore complex, and its microcompartment carriers helped us make the jump from prokaryote to eukaryote. The nucleus is a later evolutionary development, but it still uses a prokaryotic system. This is clue that helps us investigate our cellular family tree. </div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Protein+Science&rft_id=info%3Adoi%2F10.1002%2Fpro.2196&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Using+comparative+genomics+to+uncover+new+kinds+of+protein-based+metabolic+organelles+in+bacteria&rft.issn=09618368&rft.date=2012&rft.volume=&rft.issue=&rft.spage=0&rft.epage=0&rft.artnum=http%3A%2F%2Fdoi.wiley.com%2F10.1002%2Fpro.2196&rft.au=Jorda%2C+J.&rft.au=Lopez%2C+D.&rft.au=Wheatley%2C+N.&rft.au=Yeates%2C+T.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Microbiology+%2C+Biochemistry%2C+Evolutionary+Biology">Jorda, J., Lopez, D., Wheatley, N., & Yeates, T. (2012). Using comparative genomics to uncover new kinds of protein-based metabolic organelles in bacteria <span style="font-style: italic;">Protein Science</span> DOI: <a href="http://dx.doi.org/10.1002/pro.2196" rev="review">10.1002/pro.2196</a></span>
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<span style="font-size: 10pt;">For more information or classroom activities on bacterial microcomponents, post-translational modification of proteins, alcohol metabolism, or the vault complex, see:</span></div>
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<span style="font-size: 10pt;">Bacterial microcomponents – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.sciencedaily.com/releases/2008/02/080221152009.htm">http://www.sciencedaily.com/releases/2008/02/080221152009.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://schaechter.asmblog.org/schaechter/2011/04/beyond-the-bacterial-microcompartment.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+schaechter+%28Small+Things+Considered%29">http://schaechter.asmblog.org/schaechter/2011/04/beyond-the-bacterial-microcompartment.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+schaechter+%28Small+Things+Considered%29</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.microbemagazine.org/index.php/06-2010-home/1863-the-carboxysome-and-other-bacterial-microcompartments">http://www.microbemagazine.org/index.php/06-2010-home/1863-the-carboxysome-and-other-bacterial-microcompartments</a></span></div>
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<cite><span style="font-family: "cambria";"><a href="http://www.asm.org/ccLibraryFiles/Filename/.../znw00107000025.pdf"><span style="font-style: normal;">www.asm.org/ccLibraryFiles/Filename/.../znw00107000025.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://www1.cnsi.ucla.edu/arr/paper?paper_id=196039">http://www1.cnsi.ucla.edu/arr/paper?paper_id=196039</a></span></div>
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<span style="font-size: 10pt;"><a href="http://scienceblogs.com/oscillator/2010/03/bacterial_organelles.php">http://scienceblogs.com/oscillator/2010/03/bacterial_organelles.php</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.microbialcellfactories.com/content/10/1/92">http://www.microbialcellfactories.com/content/10/1/92</a></span></div>
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<span style="font-size: 10pt;">Protein post-translational modification – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.piercenet.com/browse.cfm?fldID=7CE3FCF5-0DA0-4378-A513-2E35E5E3B49B">http://www.piercenet.com/browse.cfm?fldID=7CE3FCF5-0DA0-4378-A513-2E35E5E3B49B</a></span></div>
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<span style="font-size: 10pt;"><a href="http://themedicalbiochemistrypage.org/protein-modifications.php">http://themedicalbiochemistrypage.org/protein-modifications.php</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.premierbiosoft.com/glycan/glossary/post-translational-modifications.html">http://www.premierbiosoft.com/glycan/glossary/post-translational-modifications.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.cook.rutgers.edu/~dbm/posttrans.html">http://www.cook.rutgers.edu/~dbm/posttrans.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.juliantrubin.com/encyclopedia/bioinformatics/proteomics.html">http://www.juliantrubin.com/encyclopedia/bioinformatics/proteomics.html</a></span></div>
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<span style="font-size: 10pt;">Alcohol metabolism – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.elmhurst.edu/~chm/vchembook/642alcoholmet.html">http://www.elmhurst.edu/~chm/vchembook/642alcoholmet.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CGMQFjAI&url=http%3A%2F%2Fjournals.cambridge.org%2Fproduction%2Faction%2FcjoGetFulltext%3Ffulltextid%3D980664&ei=v4lvT-KgBci-gAfuwonpBw&usg=AFQjCNEf-W1CVy-a75h8Z1s1HVLbtVhkSA">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CGMQFjAI&url=http%3A%2F%2Fjournals.cambridge.org%2Fproduction%2Faction%2FcjoGetFulltext%3Ffulltextid%3D980664&ei=v4lvT-KgBci-gAfuwonpBw&usg=AFQjCNEf-W1CVy-a75h8Z1s1HVLbtVhkSA</a></span></div>
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<span style="font-size: 10pt;"><a href="http://science.howstuffworks.com/environmental/life/human-biology/hangover4.htm">http://science.howstuffworks.com/environmental/life/human-biology/hangover4.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://hamsnetwork.org/metabolism/">http://hamsnetwork.org/metabolism/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://en.wikipedia.org/wiki/Alcohol_flush_reaction">http://en.wikipedia.org/wiki/Alcohol_flush_reaction</a></span></div>
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<span style="font-size: 10pt;"><a href="http://ethemes.missouri.edu/themes/315">http://ethemes.missouri.edu/themes/315</a></span></div>
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<span style="font-size: 10pt;">Nuclear vault complex – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.vaults.arc.ucla.edu/pages/sci-pores">http://www.vaults.arc.ucla.edu/pages/sci-pores</a></span></div>
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<span style="font-size: 10pt;"><a href="http://micro.magnet.fsu.edu/cells/nucleus/nuclearpores.html">http://micro.magnet.fsu.edu/cells/nucleus/nuclearpores.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.ks.uiuc.edu/Research/npc/">http://www.ks.uiuc.edu/Research/npc/</a></span></div>
<span style="font-family: "cambria"; font-size: 10pt;"><a href="http://en.wikipedia.org/wiki/Vault_%28organelle%29">http://en.wikipedia.org/wiki/Vault_%28organelle%29</a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com0tag:blogger.com,1999:blog-8136765635696545893.post-3206717200684056482017-10-19T06:00:00.000-04:002017-10-19T06:00:01.865-04:00Cell To Cell Tanning<div class="MsoNormal">
Biology Concepts – <u>vacuoles</u>, <u>phagocytosis</u>, <u>melanin</u>, <u>cephalopod camouflage</u></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHpkHgkkMunsHUHPI7ElbpubJv9K5J_Pu5uhNYuOlt5Yia4509fP5OR0lEumutLWlOxqu2AZ6zWPSeuhyphenhyphenXmdwgztfHdAxxC8ff4WG_N87pAChjfSBhaZPLwZVlDQO8qQDfmbzNYgrhHQpl/s1600/1-kleenex.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHpkHgkkMunsHUHPI7ElbpubJv9K5J_Pu5uhNYuOlt5Yia4509fP5OR0lEumutLWlOxqu2AZ6zWPSeuhyphenhyphenXmdwgztfHdAxxC8ff4WG_N87pAChjfSBhaZPLwZVlDQO8qQDfmbzNYgrhHQpl/s1600/1-kleenex.jpg" /></a></td></tr>
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<span style="font-size: 10pt;">Sometimes, the name of an item becomes the same</span></div>
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<span style="font-size: 10pt;">as its function. Have you ever asked for a Puff when you</span></div>
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<span style="font-size: 10pt;">needed a facial tissue? But we all ask for a Kleenex.</span></div>
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<span style="font-size: 10pt;">Vacuoles are the same, but in reverse, they are all</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">very similar, but are named based on their function.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">L</span>ast week we discussed the specific characteristics of organelles that allow them and the cells in which they work to specialize their activities. But being specific is not always more accurate. We ask for a Kleenex no matter what brand of facial tissue is handy. Many people ask for a Coke, when they really mean any soda at all.</div>
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There is an organelle that gets the same treatment. The <b>vacuole</b> is a generic membrane bound compartment; its function and name brand is usually defined by what it is carrying. Lysosomes are vacuoles, named for the lysosomal enzymes they carry. Peroxisomes are vacuoles, named for the peroxidase enzymes they carry. Branding can be important, even in biology.</div>
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<span style="font-size: 10pt;">The vacuole is a membrane bound compartment inside </span></div>
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<span style="font-size: 10pt;">the cell. The central vacuole of the plant cell is shown above,</span></div>
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<span style="font-size: 10pt;">and can occupy a huge percentage of the cell volume. It can</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">store water or carbohydrates, and can change size very rapidly.</span> </td></tr>
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Most cell types have many vacuoles or <b>vesicles</b> (small vacuoles), but there are exceptions. Plant cells generally just have one vacuole - not one type - but a total number of 1. This is called the <b>central vacuole</b>, and can occupy up to 90% of the cell volume. We have discussed its functions several times; the central vacuole is the part of the cell that fills and empties in order to induce movement of plant components, like flowers blooming and leaves folding (<a href="http://biologicalexceptions.blogspot.com/2011/11/plants-that-dont-sleep-will-take-dirt.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Plants That Don’t Sleep</span></a>). Vacuole functions seem to be quite <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">varied, from digestion to structure.</span></div>
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The <b>melanosome</b> is another type of vacuole. Take a guess how it got its name…… O.K., it’s because it carries melanin. <b>Melanin</b> (melas in Greek means black) is the pigment that gives color to your skin, hair, iris (the colored part of your eye), and even parts of your brain. One crucial function of melanin is to protect your skin cells from ultraviolet (UV) damage. This is why natives in sunnier areas have darker skin, while people from latitudes farther north and south have lighter skin tones. </div>
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<span style="font-size: 10pt;">Inuit (translated as “the people”) are a group of different </span></div>
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<span style="font-size: 10pt;">peoples of the north latitudes. In Alaska, the term Eskimo is </span></div>
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<span style="font-size: 10pt;">often used because its meaning includes the two main groups </span></div>
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<span style="font-size: 10pt;">that live there. All Inuit seem to have darker skin tones than one</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">would think was called for.</span> </td></tr>
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However, even in this there is an exception. Inuit natives in the Arctic have darker skin on average as compared to white Americans or Europeans. This may be because the amount of sunlight that reflects off the snow increases their UV exposure, or because they have been living in this environment for only 5000 years and haven’t had time to adopt a lighter skin color. Either way, you don’t see many red-headed, freckled, <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Inuits.</span></div>
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In your skin, melanin is produced by a specialized skin cell type called the melanocyte. We discussed in last week’s post that the different combinations of organelles allows cells to take on specialized function, and this is the case with melanocytes. Melanin is synthesized from the amino acid tyrosine within the melanosome, and remains stored in this organelle when it is stored, moved, and when it performs it jobs.</div>
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Only 5-10% of skin cells are melanocytes, and they are located only in the deepest layer of skin, called the <b>stratum basale</b>. (stratum = layer and basale = base or lowest) But if you look at dark skin or at a well-tanned person, it seems that there is pigment all over. You would think that freckles would be more natural, the melanocytes that produce melanin are spotted over the skin, and so are freckles. So how does a person get tanned skin evenly, or how is it that dark complexions are homogeneous over a large area?</div>
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This is where the melanosomes as organelles are so exceptional; they can move from melanocytes to keratinocytes (skin cells). This is unique amongst organelles and is still not fully understood. However, much evidence has been uncovered in just the past few years.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIfde4-Bisyx3FT4mZ06EZUyAEPKshyphenhyphenf3YvY63Sn76uSDvpIc_clySelRgTLLBgHjiJ6CzBKn1tH7B6632pmrqE7CJqprbTQlRSo1MRO5Ap79mBNr_cPWLlshrgesrXIA5Rzp3g6-KPYac/s1600/4-melanocyte+phag.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIfde4-Bisyx3FT4mZ06EZUyAEPKshyphenhyphenf3YvY63Sn76uSDvpIc_clySelRgTLLBgHjiJ6CzBKn1tH7B6632pmrqE7CJqprbTQlRSo1MRO5Ap79mBNr_cPWLlshrgesrXIA5Rzp3g6-KPYac/s320/4-melanocyte+phag.jpg" width="320" /></a></td></tr>
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<span style="font-size: 11pt;">Melanocytes are rare in the skin, but can project up into the </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">upper layers of the skin in order to spread out their melanin.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span> melanocyte is stimulated to make melanin due to UV exposure of keratinocytes. When the DNA of the skin cell is hit with UV radiation, it triggers production of a hormone called alpha-melanocyte stimulating hormone, <span style="font-family: "symbol";">a</span>lpha-MSH. This hormone acts on the melanocytes through receptors on the cell membrane (2<sup>nd</sup> messenger system, see <a href="http://biologicalexceptions.blogspot.com/2012/03/cells-are-great-multitaskers.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Multitaskers</span></a>). The message is transferred to the melanocyte nucleus and melanin is produced in melanosomes.</div>
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Next, the melanosome grows dendrites (from Greek for tree), sometimes called filipodia (like a foot). These extensions snake their way between keratinocytes and reach up into the higher layers of skin cells. The dendrites are rich in melanosomes, but research has yet to show if the melanosomes are responsible for the formation of the dendrites. This may be so, because it is not until the keratinocytes acquire melanosomes that they also start to form these filopodia.</div>
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The melanosomes end up inside the skin cells, and this is where current research is focused. Recent hypotheses for their movement include ideas that they are released from melanocytes and then taken up by keratinocytes, or that there is fusion of the keratinocyte and the melanocyte.</div>
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However, evidence from a 2010 study indicates that the keratinocyte actually swallows (phagocytoses, phag = eat and cyto = cell) the ends of the dendrites, and the included melanosomes become skin cell organelles. The keratinocyte membrane expands around the end of the dendrite, then pinches together until the two sides meet each other. Part of the melanocyte, its cytoplasm, its membrane, and its melanosomes ends up as part of the keratinocyte. Your trip to the beach causes your cells to eat each other, cool!</div>
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The phagocytosed melanosomes can have two fates, but neither is what you would expect. Usually phagocytosed vacuoles are merged with lysosomes and the contents are degraded. But not so for the melanosome.</div>
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Some are pushed out into new keratinocyte filopodia. These dendrites can then be phagocytosed by other keratinocytes. In this way, the melanin produced by the few melanocytes can be spread through out the layers and surface area of the skin cells and result in a continuous skin tone. However, if you have fewer melanocytes, or they have a mutated <span style="font-family: "symbol";">alpha</span>-MSH receptor that forces them to produce more local melanin, you end up with freckles.</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLOTh4TwjMKbkKDCeMVNjcIVMmEECv01IaVGI8SdvWHwdP-NuQGjZlNZnmEvUPbrMi0RXaPeKb7vaYntnemzRrdgHMiNTmt83bVvWgtPpBV_LT2sv-0Q0bo0E8lByRCKcYMrZxnwxa7lff/s1600/5-nucleus+mel.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLOTh4TwjMKbkKDCeMVNjcIVMmEECv01IaVGI8SdvWHwdP-NuQGjZlNZnmEvUPbrMi0RXaPeKb7vaYntnemzRrdgHMiNTmt83bVvWgtPpBV_LT2sv-0Q0bo0E8lByRCKcYMrZxnwxa7lff/s320/5-nucleus+mel.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">These micrographs show that melanosomes aggregate around</span></div>
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<span style="font-size: 10pt;">the nucleus of keratinocytes that have been exposed to UV</span></div>
<span style="font-family: "cambria"; font-size: 10pt;">radiation in order to protect the DNA in the nucleus.</span> </td></tr>
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The second fate for the melanosomes occurs when they get the right signal, and is just as amazing. The UV rays that can stimulate the DNA to make alpha-MSH can also induce DNA damage; this is the main reason for melanin production. In response to increased sun exposure, the keratinocytes that take up the melanosomes will move them into position between the UV source and their DNA, like a hat worn by the nucleus. There the melanin absorbs the radiation like nature’s own <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">sunscreen</span>.</div>
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In truth, melanin is really three different pigments. Eumelanin (eu = true) is dark brown and is the most common type of melanin. But the same cells and melanosomes also produce pheomelanin (pheo = dusky) which is more reddish in color. Pheomelanin is responsible for red hair and for the freckle color in fair-skinned individuals.</div>
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Finally, there is neuromelanin in the brain, which gives a dark color to the portions of the brain like the <b>substantia nigra</b> (Latin for black substance). This brain structure coordinates muscle movement, and when these cells die or malfunction, the result is Parkinson’s disease. The melanin in these cells is actually just a byproduct of dopamine production. Parkinson’s disease can be treated, at least in its early stages, with synthetic dopamine.</div>
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Although it serves no known function in the midbrain, melanin does help in ways other than UV absorption. Different stressors, like chemicals, oxidative damage, and high temperature are also suppressed by melanin.</div>
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Melanin is particularly important for cephalopods, like squid, cuttlefish, and octopuses (yes, the plural of octopus is octopuses or octopodes, not octopi). These animals can disguise themselves within their environments and this task requires melanin. Under their skin, cephalopods have three or four layers of cells that allow them to create many colors and surface characteristics.</div>
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Chromatophores are the top level. The have saccules of melanin that can change shape. When stretched out, they show much color, but when relaxed, only pinpoints of color show. Each saccule is attached to many muscles and each muscle is innervated by several neurons; the octopus has fine control of each and every saccule, and each saccule can rapidly assume a different size and shape. This makes many shades and patterns possible</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhohZKju271NFukNE7fWbbKkXIAZNvkS18qjQKNmvx0FX9AP90kRwymqYsG2BMzMRjg5uBiwxRfLACqn66yPLG9gBsYAlxoZPxzH99leSA2yOCF1UjPaeqjBh5s7e2qxBQu8xYMQdxhstrU/s1600/6-bluering700.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="182" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhohZKju271NFukNE7fWbbKkXIAZNvkS18qjQKNmvx0FX9AP90kRwymqYsG2BMzMRjg5uBiwxRfLACqn66yPLG9gBsYAlxoZPxzH99leSA2yOCF1UjPaeqjBh5s7e2qxBQu8xYMQdxhstrU/s320/6-bluering700.jpg" width="320" /></a></td></tr>
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<span style="font-size: 10pt;">Cephalopods use several specialized cell types to hide </span></div>
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<span style="font-size: 10pt;">themselves from predators or to display for a mate or </span></div>
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<span style="font-size: 10pt;">rival. These special functions are possible, in part, because </span></div>
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<span style="font-size: 10pt;">of the organelles they possess. In the case of the blue ring </span></div>
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<span style="font-size: 10pt;">octopus, the blue is not from melanin, and is used to warn </span></div>
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<span style="font-size: 10pt;">of its toxicity, not to hide.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Below</span> the chromatophores are the iridophores. These are like little mirrors that can also change angle position through many muscle and nerve controls. This allows the cephalopod to change the reflectivity and shine of its surface. Under this layer are the leucophores. They specialize in reflecting the dominant light wavelengths that they receive. These are the cells that help the octopus to match its surrounding colors so well (<a href="http://www.ted.com/talks/lang/en/david_gallo_shows_underwater_astonishments.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">amazing video</span></a>). Lastly, only some cephalopods have a layer of photophores that produce light (bioluminescence). We will talk about this amazing feat in a future series of posts.</div>
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Working together, and coordinated by their fantastic eyes, cephalopod skin cell layers can perform some amazing tricks to help the organism to survive. All this muscle control and sensory input requires a big brain, and cephalopods have the biggest brains of all the <b>invertebrates</b> (no backbone) and bigger than many vertebrates. I think they should be worthy of a post or two in the future, especially since almost all cephalopods are color blind!</div>
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But back to melanin. Squid and octopus ink is also made of melanin, and is most often used to confuse predators, but I especially like its effect when used with eggs, water, and flour – try squid ink pasta sometime, you’ll like it. </div>
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Finally, there is a new way that melanin is helping science. Melanosomes are big, and they tend to fossilize well, so scientists are starting to learn what the coloration of dinosaurs might have been based on the preserved melanosomes and their included melanins.</div>
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We have looked at several organelle types, and have seen how they allow for specialized cell functions. But what if you had to get along without organelles, could a cell cope? We'll see about this next week.</div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=FASEB+Journal&rft_id=info%3Adoi%2F10.1096%2Ffj.10-159046&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Melanin+transfer+in+human+skin+cells+is+mediated+by+filopodia%E2%80%94a+model+for+homotypic+and+heterotypic+lysosome-related+organelle+transfer&rft.issn=&rft.date=2010&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Suman+K.+Singh%2C+Robin+Kurfurst%2C+Carine+Nizard%2C+Sylvianne+Schnebert%2C+Eric+Perrier+and+Desmond+J.+Tobin&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Molecular+Biology">Suman K. Singh, Robin Kurfurst, Carine Nizard, Sylvianne Schnebert, Eric Perrier and Desmond J. Tobin (2010). Melanin transfer in human skin cells is mediated by filopodia—a model for homotypic and heterotypic lysosome-related organelle transfer <span style="font-style: italic;">FASEB Journal</span> DOI: <a href="http://dx.doi.org/10.1096/fj.10-159046" rev="review">10.1096/fj.10-159046</a></span>
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<span style="font-size: 10pt;">For more information and classroom activities on vacuoles, melanin, melanosome movement, or cephalopod camouflage, see:</span></div>
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<span style="font-size: 10pt;">Vacuoles – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.biology4kids.com/files/cell_vacuole.html">http://www.biology4kids.com/files/cell_vacuole.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://kentsimmons.uwinnipeg.ca/cm1504/vacuoles.htm">http://kentsimmons.uwinnipeg.ca/cm1504/vacuoles.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://micro.magnet.fsu.edu/cells/plants/vacuole.html">http://micro.magnet.fsu.edu/cells/plants/vacuole.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.nature.com/scitable/topicpage/plant-vacuoles-and-the-regulation-of-stomatal-14163334">http://www.nature.com/scitable/topicpage/plant-vacuoles-and-the-regulation-of-stomatal-14163334</a></span></div>
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<span style="font-size: 10pt;"><a href="http://bcs.whfreeman.com/thelifewire/content/chp28/2802001.html">http://bcs.whfreeman.com/thelifewire/content/chp28/2802001.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.bscb.org/?url=softcell/vacuole">http://www.bscb.org/?url=softcell/vacuole</a></span></div>
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<span style="font-size: 10pt;"><a href="http://library.thinkquest.org/27819/ch3_3.shtml">http://library.thinkquest.org/27819/ch3_3.shtml</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.illuminatedcell.com/Vacuolarsystem.html">http://www.illuminatedcell.com/Vacuolarsystem.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://cfeil.tripod.com/vacuoles.htm">http://cfeil.tripod.com/vacuoles.htm</a></span></div>
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<span style="font-size: 10pt;">Melanin – </span></div>
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<span style="font-size: 10pt;"><a href="http://www.pbs.org/race/000_About/002_04-teachers-06.htm">http://www.pbs.org/race/000_About/002_04-teachers-06.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.healthofchildren.com/A/Albinism.html">http://www.healthofchildren.com/A/Albinism.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.webexhibits.org/causesofcolor/7F.html">http://www.webexhibits.org/causesofcolor/7F.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.buzzle.com/articles/enzymatic-browning.html">http://www.buzzle.com/articles/enzymatic-browning.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=28&ved=0CHIQFjAHOBQ&url=http%3A%2F%2Fwww.curriculumsupport.education.nsw.gov.au%2Fsecondary%2Fscience%2Fassets%2Faifst%2FExperiments%2Fapple_browning.pdf&ei=du5lT_zTHMXdtgen34z-DQ&usg=AFQjCNHdPQW">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=28&ved=0CHIQFjAHOBQ&url=http%3A%2F%2Fwww.curriculumsupport.education.nsw.gov.au%2Fsecondary%2Fscience%2Fassets%2Faifst%2FExperiments%2Fapple_browning.pdf&ei=du5lT_zTHMXdtgen34z-DQ&usg=AFQjCNHdPQWxis8p_rvs8t0bWgNg3yqyWQ</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.cl.cam.ac.uk/~jgd1000/melanin.html">http://www.cl.cam.ac.uk/~jgd1000/melanin.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.sciencedaily.com/releases/2010/10/101014171144.htm">http://www.sciencedaily.com/releases/2010/10/101014171144.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.clinuvel.com/en/dermatology/melanin/function-skin-pigment">http://www.clinuvel.com/en/dermatology/melanin/function-skin-pigment</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.rastafarian.net/what_is_melanin.htm">http://www.rastafarian.net/what_is_melanin.htm</a></span></div>
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<span style="font-size: 10pt;">Melanosome movement – </span></div>
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<span style="font-size: 10pt;"><a href="http://jcs.biologists.org/content/121/24/3995.full">http://jcs.biologists.org/content/121/24/3995.full</a></span></div>
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<span style="font-size: 10pt;"><a href="http://news.nationalgeographic.com/news/2010/01/100127-dinosaur-feathers-colors-nature/">http://news.nationalgeographic.com/news/2010/01/100127-dinosaur-feathers-colors-nature/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://en.wikipedia.org/wiki/Griscelli_syndrome">http://en.wikipedia.org/wiki/Griscelli_syndrome</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.medscape.com/viewarticle/462276_3">http://www.medscape.com/viewarticle/462276_3</a></span></div>
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<span style="font-size: 10pt;">Cephalopod camouflage – </span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.thecephalopodpage.org/.../HowCephalopodsChangeColor.pdf"><span style="font-style: normal;">www.the</span><b><span style="font-style: normal;">cephalopod</span></b><span style="font-style: normal;">page.org/.../How</span><b><span style="font-style: normal;">Cephalopods</span></b><span style="font-style: normal;">Change</span><b><span style="font-style: normal;">Color</span></b><span style="font-style: normal;">.pdf</span></a></span></cite></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.thecephalopodpage.org/cephschool/CephalopodVision.pdf"><span style="font-style: normal;">www.the</span><b><span style="font-style: normal;">cephalopod</span></b><span style="font-style: normal;">page.org/cephschool/</span><b><span style="font-style: normal;">Cephalopod</span></b><span style="font-style: normal;">Vision.pdf</span></a></span></cite></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.thecephalopodpage.org/.../ColorChangeInCephalopods.pdf"><span style="font-style: normal;">www.the</span><b><span style="font-style: normal;">cephalopod</span></b><span style="font-style: normal;">page.org/.../</span><b><span style="font-style: normal;">Color</span></b><span style="font-style: normal;">ChangeIn</span><b><span style="font-style: normal;">Cephalopods</span></b><span style="font-style: normal;">.pdf</span></a></span></cite></div>
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<span style="font-size: 10pt;"><a href="http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cephalopods/colordisguise.cfm">http://nationalzoo.si.edu/Animals/Invertebrates/Facts/cephalopods/colordisguise.cfm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.mbl.edu/mrc/hanlon/coloration.html">http://www.mbl.edu/mrc/hanlon/coloration.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.talkingscience.org/2011/01/are-cephalopods-really-colorblind/">http://www.talkingscience.org/2011/01/are-cephalopods-really-colorblind/</a></span></div>
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<span style="font-size: 10pt;"><a href="http://marinediscovery.arizona.edu/lessonsF00/blennies/2.html">http://marinediscovery.arizona.edu/lessonsF00/blennies/2.html</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.oercommons.org/courses/cephalopod-lesson-plans">http://www.oercommons.org/courses/cephalopod-lesson-plans</a></span></div>
<span style="font-family: "cambria"; font-size: 10pt;"><a href="http://tolweb.org/treehouses/?treehouse_id=4225">http://tolweb.org/treehouses/?treehouse_id=4225</a></span></div>
</div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1tag:blogger.com,1999:blog-8136765635696545893.post-42353322250217825352017-10-12T06:00:00.000-04:002017-10-12T06:00:09.070-04:00Cells Are Great Multitaskers<div class="MsoNormal">
Biology concepts – <u>compartmentalization</u>, <u>organelle function</u>, <u>cellular biochemistry</u></div>
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<span style="font-size: 10pt;">This chart represents a portion of the cellular reactions </span></div>
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<span style="font-size: 10pt;">that are taking place every second in a mammalian cell. </span></div>
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<span style="font-size: 10pt;">It looks more like a multicolored plate of pasta, but </span></div>
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<span style="font-size: 10pt;">shows you how complex a single cell is, and remember </span></div>
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<span style="font-size: 10pt;">that this doesn’t even count all the reactions for one cell </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">to be able to talk to another cell.</span> </td></tr>
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It is hard to estimate the number of reactions that must take place in a cell every second in order to keep a cell alive and performing its jobs(s)...... but I bet it is more than <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">seven</span><span style="background-color: white;"> or eight.</span> </div>
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The typical mammalian cell contains 2000 or more different proteins as well as many thousands of non-proteins (lipids, carbohydrates, and nucleic acids). Each molecule is crucial for carrying out chemical reactions, and each individual molecule is itself produced, modified, and destroyed by chemical reactions. </div>
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When I started to think about all this chemical activity, I looked to see if someone had counted, or at least estimated, the number of reactions taking place in the cell at any one time. I got no answer, not even a reliable guess from a credible source. </div>
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Think of it in this light, a plant cell has to perform more than twenty reactions to convert one photon of light into the chemical energy that will later be used for the synthesis of glucose. Each of these twenty reactions is occurring simultaneously at least hundreds of times in every <b>chloroplast</b> of the plant cell, and a single plant cell might have more than one hundred chloroplasts. The numbers add up fast, but remember that production of carbohydrate from light energy is just one of thousands of functions of a plant cell. There are chemical reactions occurring every second for all of these functions.</div>
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All this chemistry results in perhaps hundreds of thousands or millions of reactions each second, and all taking place within the confines of a cell that is too small to be seen with the naked eye. Wow!</div>
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When talking to students, I often use the analogy that a cell is like a factory, producing many different products at the same time. Not unlike a factory, a cell has to perform many functions, such as energy production, product manufacture, oversight and management, transportation of products, quality checks, and cleanup. What complicates matters is that all these different jobs have to be able to occur simultaneously. </div>
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<span style="font-size: 10pt;">I often use the analogy that a cell is like a factory, with </span></div>
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<span style="font-size: 10pt;">different departments. Other like the cell as a city </span></div>
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<span style="font-size: 10pt;">analogy. I even had one student make the analogy </span></div>
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<span style="font-size: 10pt;">that the cell is like a movie set, where the nucleus is </span></div>
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<span style="font-size: 10pt;">the director, and the plasma membrane is the fence </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">around the movie lot, etc. She got an A.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">How</span> can a factory, or a cell for that matter, keep all the parts for all the different products, all the different workers, and all the different processes and jobs from messing each other up? A factory does this by setting up departments, where individual jobs take place, and then creating management teams that coordinate the work of the different departments—although to often there is too much management and too little production, but that is another matter. </div>
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The business and manufacturing industries stole this strategy from the cell, just as most our good ideas have been copied from nature. The cell uses compartments to increase the efficiency of all its needed chemical reactions. In <b>eukaryotic </b>(eu = true, and karyo= nucleus)<b> </b>cells, the compartments are called <b>organelles </b>(organ = instrument and elle = small), most of which are membrane bound containers.</div>
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Remember in our discussion of why cells must be small (<a href="http://biologicalexceptions.blogspot.com/2011/08/its-all-in-numbers-sizes-in-nature.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">It’s All In The Numbers</span></a>) we said that <b>mixing rate</b> (time needed for a molecule to become evenly dispersed in a cell) and <b>traffic time</b> (time needed for two molecules needed for a certain reaction to find one another) are important for determining the maximum size of a cell. </div>
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Membrane bound organelles sequester needed components and create different local environments so that their mixing rates and traffic times are reduced. The result is a cell that is more efficient and can be bigger. This is evidenced by the fact that <b>prokaryotic </b>(pro = before)<b> </b>cells, such as bacteria, don’t have organelles and are about 50 times smaller than eukaryotic cells which have evolved organelles.</div>
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<span style="font-size: 10pt;">The nucleus has two membranes that form an envelope. </span></div>
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<span style="font-size: 10pt;">The outer membrane is continued as the endoplasmic </span></div>
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<span style="font-size: 10pt;">reticulum (ER), another vital cell organelle. The ribosome </span></div>
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<span style="font-size: 10pt;">attached to the ER, so it is easy to see how the organelles </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">work together to make a functioning cell.</span> </td></tr>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">The</span> membranes of organelles look a lot like the membrane that surrounds the cell itself, but organelle membranes are often modified for their particular job. Take the <b>nucleus</b> (Welsh for "kernel of a nut," meaning the central part of a thing) for instance. It has two membranes and <b>nuclear pores</b> that run through both membranes are very specific for what they will let into and out of the nucleus.<br />
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The plasma membrane of the cell also limits the passage of molecules, but the nuclear pores are a complex of many unique proteins and this structure that is nowhere to be seen on the cell’s plasma membrane. Just like the membrane of the cell separates what is in the cell from what is outside the cell, the membrane of the organelle separates the needed components of their reactions from all the unneeded components of the cell.</div>
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In addition, many chemical reactions in organelles require the membrane as a workbench. Thousands of reactions take place in or across the membrane. This is an important function of many types of organelles, they increase the membrane surface area of a cell without making it bigger. </div>
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Some cellular reactions produce or use an intermediate molecule that must be separated across a membrane in order for the rest of the reaction to take place. This is the case for the <b>mitochondrion</b> – the energy producer in eukaryotic cells. To produce <b>ATP</b> (adenosine triphosphate, the chemical currency unit of energy in the cell), the mitochondrion sets up a gradient of protons between two membranes (remember that the nucleus has two membranes also) of the mitochondrion. The energy from the leaking of protons back into the inner space is used to produce ATP. We will talk more about these organelles with two membranes in an upcoming post.</div>
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<span style="font-size: 10pt;">Second messenger systems allow for messages from outside </span></div>
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<span style="font-size: 10pt;">the cell to be transmitted throughout the cell. There are three </span></div>
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<span style="font-size: 10pt;">general types, including one for gases like nitric oxide. In all, </span></div>
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<span style="font-size: 10pt;">there are more than two dozen different signal transduction </span></div>
<span style="font-family: "cambria"; font-size: 10pt;">cascades, each with its own set of reactions.</span> </td></tr>
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Likewise, the outer membrane of the cell has many jobs that require messages to be transferred from one side of the membrane to the other. Called <b>second messenger systems</b>, these reactions are mechanisms to bring messages from outside the cell to the inside of the cell without the need for anything to cross the cell’s <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">boundary</span>.</div>
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In some cases, the membrane is not enough compartmentalization. The <b>lysosome</b> is an interesting organelle whose job is to break down many complexes that are brought into a cell and to recycle old organelles so the cell can reuse the parts. To do this, the lysosome contains proteins that can eat up other proteins, lipids, and carbohydrates. Unfortunately, these are the exact same molecules that make up the cell and the lysosomal membrane themselves. So why doesn’t the lysosome digest itself, and the entire cell for that matter?</div>
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The protein enzymes in the lysosome work efficiently within a narrow range of acid pH. Therefore, this organelle is acidified when produced. If the lysosome ruptures, the 7.2 pH of the cytoplasm will inactivate the lysosomal acid hydrolases, so the cell is protected. In addition, the lysosome membrane has many sugars stuck to it that act as a buffer between the lipids and proteins of the lysosomal membrane and lysosomal enzymes. There probably is some damage to the lysosome membrane, but repair reactions also help to keep the membrane intact. The cell often has redundant systems for safety.</div>
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So, we have seen that many of the organelles function to keep things sequestered in the cell, either for protection, organization, efficiency, or function. However, there are other reasons why organelles are a good idea.</div>
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<span style="font-size: 10pt;">Osteoclasts and osteoblasts are hard workers, so much so </span></div>
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<span style="font-size: 10pt;">that they needed more than one set of instructions for their </span></div>
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<span style="font-size: 10pt;">work. The osteoclast above shows multiple nuclei for many </span></div>
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<span style="font-size: 10pt;">DNA copies. Sometimes separate osteoblasts will join </span></div>
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<span style="font-size: 10pt;">together to form a multinucleated giant cell.</span></div>
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Organelles increase specificity, both for individual reactions and for cellular activity as a whole. Many cells in multicellular organisms are specialized for a certain function, and their organelles help them carry out this function. For instance, muscle cells are specialized for contraction, and this requires lots of energy. Therefore, they need many mitochondria, but few other types of organelles. These cells might contain 10-100 times more mitochondria than other cell types.</div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Likewise</span>, <b>osteoclasts</b> (osteo = bone, clast = break) cells break down bone – and yes, you are breaking down and rebuilding your bones every second of every day. This activity requires many proteins to be produced, and one set of DNA instruction housed in one nucleus is often insufficient for the job. Therefore, these cells often have two or more nuclei in order to get the job done. In these ways, specialization of organelle compartments and combinations allows for specialization of cellular function.</div>
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<span style="font-size: 10pt;">Centrioles are organelles important for the cellular </span></div>
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<span style="font-size: 10pt;">division. They are also a target for cancer therapy, </span></div>
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<span style="font-size: 10pt;">since many cancer cells have more than the regular </span></div>
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<span style="font-size: 10pt;">set of two centrioles. </span></div>
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As we have seen in every topic we have investigated, there are exceptions in the world of organelles. Some organelles are not membrane bound bags that carry things around or house certain reactions. <b>Ribosomes</b> are cellular organelles that make proteins, but they have no membrane. The <b>cytoskeleton</b> elements help the cell hold its structure, help the cell move, and help move other organelles move around within the cell, but they are not membrane bound either. Other cellular components, like the <b>mitotic spindles </b>of the<b> centrioles</b> that pull chromosomes apart when the cell undergoes mitosis are proteins that are present at only certain times in the animal cell. Even more confusing, plant cells divide similar to animal cells, but don’t have <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">centriole organelles.</span></div>
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The take home message is that these organelles, whether membrane bound or not, perform vital services for the cell and make the many cellular reactions possible. The general modus operandi for organelles is that they carry out their functions with in the cell, but one type of organelle is the exception, it’s the traveling organelle.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Genetics+and+molecular+research+%3A+GMR&rft_id=info%3Apmid%2F25062413&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=New+roles+of+filopodia+and+podosomes+in+the+differentiation+and+fusion+process+of+osteoclasts.&rft.issn=&rft.date=2014&rft.volume=13&rft.issue=3&rft.spage=4776&rft.epage=87&rft.artnum=&rft.au=Song+RL&rft.au=Liu+XZ&rft.au=Zhu+JQ&rft.au=Zhang+JM&rft.au=Gao+Q&rft.au=Zhao+HY&rft.au=Sheng+AZ&rft.au=Yuan+Y&rft.au=Gu+JH&rft.au=Zou+H&rft.au=Wang+QC&rft.au=Liu+ZP&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CBiochemistry%2C+Cell+Biology%2C+Evolutionary+Biology%2C+Molecular+Biology%2C+Zoology">Song RL, Liu XZ, Zhu JQ, Zhang JM, Gao Q, Zhao HY, Sheng AZ, Yuan Y, Gu JH, Zou H, Wang QC, & Liu ZP (2014). New roles of filopodia and podosomes in the differentiation and fusion process of osteoclasts. <span style="font-style: italic;">Genetics and molecular research : GMR, 13</span> (3), 4776-87 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/25062413" rev="review">25062413</a></span><br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+cellular+physiology&rft_id=info%3Apmid%2F15828028&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Organization+of+transcriptional+regulatory+machinery+in+osteoclast+nuclei%3A+compartmentalization+of+Runx1.&rft.issn=0021-9541&rft.date=2005&rft.volume=204&rft.issue=3&rft.spage=871&rft.epage=80&rft.artnum=&rft.au=Saltman+LH&rft.au=Javed+A&rft.au=Ribadeneyra+J&rft.au=Hussain+S&rft.au=Young+DW&rft.au=Osdoby+P&rft.au=Amcheslavsky+A&rft.au=van+Wijnen+AJ&rft.au=Stein+JL&rft.au=Stein+GS&rft.au=Lian+JB&rft.au=Bar-Shavit+Z&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CBiochemistry%2C+Cell+Biology%2C+Evolutionary+Biology%2C+Molecular+Biology">Saltman LH, Javed A, Ribadeneyra J, Hussain S, Young DW, Osdoby P, Amcheslavsky A, van Wijnen AJ, Stein JL, Stein GS, Lian JB, & Bar-Shavit Z (2005). Organization of transcriptional regulatory machinery in osteoclast nuclei: compartmentalization of Runx1. <span style="font-style: italic;">Journal of cellular physiology, 204</span> (3), 871-80 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/15828028" rev="review">15828028</a></span>
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<span style="font-size: 10pt;">For more information on organelles, see:</span></div>
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<span style="font-size: 10pt;">Organelles – </span></div>
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<span style="font-size: 10pt;"><a href="http://biology.clc.uc.edu/courses/bio104/cells.htm">http://biology.clc.uc.edu/courses/bio104/cells.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://people.usd.edu/~bgoodman/ReviewFrames.htm">http://people.usd.edu/~bgoodman/ReviewFrames.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://library.thinkquest.org/trio/TR0110561/organelles.htm">http://library.thinkquest.org/trio/TR0110561/organelles.htm</a></span></div>
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<span style="font-size: 10pt;"><a href="http://www.cellsalive.com/cells/cell_model.htm">http://www.cellsalive.com/cells/cell_model.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://utahscience.oremjr.alpine.k12.ut.us/sciber00/7th/cells/sciber/orgtable.htm">http://utahscience.oremjr.alpine.k12.ut.us/sciber00/7th/cells/sciber/orgtable.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.sumanasinc.com/webcontent/animations/content/organelles.html">http://www.sumanasinc.com/webcontent/animations/content/organelles.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.youtube.com/watch?v=LP7xAr2FDFU">http://www.youtube.com/watch?v=LP7xAr2FDFU</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.biology4kids.com/files/cell_main.html">http://www.biology4kids.com/files/cell_main.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.vetmed.vt.edu/education/curriculum/vm8054/labs/lab3/lab3.htm">http://www.vetmed.vt.edu/education/curriculum/vm8054/labs/lab3/lab3.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.nobelprize.org/educational/medicine/cell/">http://www.nobelprize.org/educational/medicine/cell/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://waynesword.palomar.edu/lmexer1a.htm">http://waynesword.palomar.edu/lmexer1a.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.lessonplansinc.com/biology_lesson_plans_cell_organelles.php">http://www.lessonplansinc.com/biology_lesson_plans_cell_organelles.php</a></span></div>
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<span style="font-size: 11pt;"><a href="http://alex.state.al.us/lesson_view.php?id=23925">http://alex.state.al.us/lesson_view.php?id=23925</a></span></div>
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<span style="font-size: 11pt;"><a href="http://teachingtoday.glencoe.com/lessonplans/the-cell">http://teachingtoday.glencoe.com/lessonplans/the-cell</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.galaxygoo.org/biochem/CellProject/the_cell.html">http://www.galaxygoo.org/biochem/CellProject/the_cell.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.etap.org/demo/grade7_science/instruction2tutor.html">http://www.etap.org/demo/grade7_science/instruction2tutor.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://blog.sciencegeekgirl.com/2010/01/12/hands-on-class-activities-on-the-cell/">http://blog.sciencegeekgirl.com/2010/01/12/hands-on-class-activities-on-the-cell/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.ehow.co.uk/info_8237178_student-activities-cell-organelles.html">http://www.ehow.co.uk/info_8237178_student-activities-cell-organelles.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.schools.manatee.k12.fl.us/072JOCONNOR/celllessonplans/lesson_plan__cell_structure_and_function.html">http://www.schools.manatee.k12.fl.us/072JOCONNOR/celllessonplans/lesson_plan__cell_structure_and_function.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://sciencenetlinks.com/lessons/cells-2-the-cell-as-a-system/">http://sciencenetlinks.com/lessons/cells-2-the-cell-as-a-system/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://classroom.jc-schools.net/sci-units/cells.htm">http://classroom.jc-schools.net/sci-units/cells.htm</a></span></div>
<span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.teach-nology.com/teachers/lesson_plans/science/biology/cell/">http://www.teach-nology.com/teachers/lesson_plans/science/biology/cell/</a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com2tag:blogger.com,1999:blog-8136765635696545893.post-75037349382256748582017-10-05T06:00:00.000-04:002017-10-05T06:00:07.734-04:00More Than The Sum Of Its Parts<div class="MsoNormal">
Biology concepts – <u>symbiosis</u>, <u>lichen products</u>, <u>weathering</u>, <u>pedogenesis</u></div>
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<span style="font-size: 11pt;">During the Depression, the Civilian Conservation </span></div>
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<span style="font-size: 11pt;">Corps got the idea to have unemployed people earn </span></div>
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<span style="font-size: 11pt;">some money by planting kudzu vine in the South to </span></div>
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<span style="font-size: 11pt;">reduce erosion. It seemed like a good idea at the </span></div>
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<span style="font-size: 11pt;">time, but in biology, not all good ideas stay good </span></div>
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<span style="font-size: 11pt;">ideas. Yes, there is a cabin under all that vine.</span></div>
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Will today’s good idea be tomorrow’s bust? In nature, an adaptation may provide an advantage today, yet be the cause of extinction tomorrow. Conditions rarely remain the same and never duplicate themselves. Very few organisms could develop identically at different times and places – but lichens are the <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">exception</span>. </div>
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Genetic studies of lichens from different places and of different ages show us that these amazing organisms have developed numerous times. This doesn’t mean that different lichens have appeared and gone extinct, only to make a comeback. It means that at least seven times in the history of life on Earth, a fungus and a photobiont (algae or cyanobacteria) have developed the exact same symbiotic relationship that we see in today's lichens.</div>
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Each of these original ideas has used different fungus types and sometimes different photobionts, but their relationship is identical in each case. Think of that, lichens are such a good idea that over 4 billion years, in deserts, forests, and coastlines lichens have invented themselves again and again. That must be one good idea!</div>
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One reason lichens have been so exceptional is that they can survive in places that can’t support much life. This may be the link in the separate development of lichens time and time again. One reason for their success in desolate environments is that they are veritable chemical factories. They make many products, some of which have uses in their stark homelands. Many of these products are unique to lichens.</div>
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<b>Lichen acids</b> (also called lichen substances or lichen products) are chemicals made by the lichen by further processing of regular cellular products, making them <b>secondary metabolites</b>. Lichens make 600-800 of these products, and all but 60-80 of them are unique to lichens. </div>
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<span style="font-size: 11pt;">The lichens themselves can be different colors, based on their</span></div>
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<span style="font-size: 11pt;">constituents. However, their colors may be hidden under the </span></div>
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<span style="font-size: 11pt;">different lichen products excreted from the cortex onto the thallus.</span></div>
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<span style="font-size: 11pt;">Here the lichen products are white and crystalline, and probably </span></div>
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<span style="font-size: 11pt;">mean that the conditions aren’t great for lichen growth.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Even</span> more amazing, neither the fungus nor the algae (or cyanobacteria) that make up the lichen produce lichen acids when they are on their own. Many are made by the fungal component of the lichen, but the type of photobiont included in the symbiosis will control which lichen acids can be made. Most are produced as crystalline powders that are deposited extracellularly, on the stalks or the thallus bodies.</div>
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Making lichen acids would be wasted energy if they did not confer some advantage to the lichen, and evidence suggests that they do have specific functions. Lichens that are growing rapidly (for them, still might be only 1 mm/year) make very little of these lichen products. When exerting energy to make biomass, the lichen doesn’t need the lichen acids. This suggests that the acids are most needed when the going is tough, when lichens are trying to survive in poor conditions, ie. on difficult substrates, in drought, in extreme temperature or radiation, etc.</div>
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What is more, there must be very specific functions for the different acids based on what the lichen needs to do to survive. Lichens of identical morphology and made up of the same component fungus and algae can make very different acids, depending on their location or environment. Lichens can be grouped into complexes of similar organisms, but they may make different lichen acids. </div>
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For example, the <i>Ramalina siliquosa</i> complex of lichens is found on the Atlantic coastline of Europe. Low on the cliffs, most exposed to the sun and saltwater, <i>R. cuspidate</i> produces a lichen acid called stictic acid. However, high on the cliffs, away from the wind and facing toward the continent, <i>R. crassa</i> produces lots of hypoprotocetraric acids, but no stictic acid at all. Finally, <i>R. stenoclada</i> lives in the region between the other lichens, and produces a different lichen acid, norstictic acid. These different positions must present different growth challenges, and the lichens respond by making different acids.</div>
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So what do these lichen products do for the symbiots? They can dissolve rock to help anchor the lichen, and they can increase membrane permeability to permit flow of carbohydrates from the photobiont to the mycobiont. Many functions have been proposed and demonstrated, and one lichen acid, usnic acid, is a particularly good example of many of these functions. </div>
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<span style="font-size: 11pt;">Usnic acid is a dye that provides many advantages to the lichen,</span></div>
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<span style="font-size: 11pt;">but has also been a traditional dye for yarn for hundreds of years.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Usnic acid</span> was first described in 1844, and is a yellow-green dye. Its color provides protection for the lichen from damage by visible and UV light, but this is just the beginning. Usnic acid is also important for protection of the lichen from predation. It has anti-herbivore properties, meaning that tastes bad or is toxic to the snails that like to make a meal of lichens. It has the same effect on insects and many fungi and microbes. </div>
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Antibacterial properties are particular strong for usnic acid. Many lichen acids are effective against a group of bacteria called Gram<sup>+</sup>. These include <i>Mycobacterium tuberculae</i>, several streptococci and staphylococci and some pnemuococcus. But a 2011 study indicates that usnic acid can go even further, and is toxic to <i>Helicobacter pylori</i>, the organism responsible for causing many stomach ulcers. Importantly, the usnic acid is not toxic to the photobiont component, whether it be cyanobacteria or algae. In addition, usnic acid has demonstrated anti-inflammatory properties and is a painkiller (analgesic). </div>
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But the most promising and surprising activity of lichen acids is as a degrader of prion proteins. Misfolded prion proteins are lethal to humans and other organisms (see -<a href="http://biologicalexceptions.blogspot.com/2011/11/infectious-genetic-disease-better-sleep.html">An Infectious Genetic Disease</a>) and are resistant to being broken down by all known human protease enzymes. But a few lichens can produce a protease that destroys prions, some down to the level of undetectability. Fungi themselves are susceptible to prion diseases, so this may be why the lichens produce anti-prion enzymes, but no one has checked lichens for prions. Not enough is known yet to predict if lichen products could be used as treatments for Creutzfeld-Jakob or fatal familial insomnia; here’s your chance to win a Nobel Prize!</div>
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This may be an important human use for lichens, but humans have been using lichens for thousands of years. Many of the dyes we use are lichen acid based, as is the litmus dye used in pH paper. Other uses have been more inventive, like as stuffing in Egyptian mummies and in Native American Indian diapers! If these don’t appeal to you, perhaps the Iceland-made lichen schnapps will be more your style. It supposedly tastes a lot like mouthwash.</div>
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However, we are amateurs compared to lichens in using the lichen acids. Lichens also use these products to grown on rocks. No soil needed. Crustose lichens are firmly attached to rock surfaces; they can’t be separated without damage…. to the rock.</div>
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<span style="font-size: 11pt;">Some lichens can protect themselves from poor environments by </span></div>
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<span style="font-size: 11pt;">Living within the rocks. Euendolithic lichens, like the one shown </span></div>
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<span style="font-size: 11pt;">above, bore into the rock using lichen acids, and then grow under </span></div>
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<span style="font-size: 11pt;">the surface of the rock. “You make a better door than a window,”</span></div>
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<span style="font-size: 11pt;">apparently doesn’t apply to rocks, because the endolithic lichens still</span></div>
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<span style="font-size: 11pt;">get enough light to perform photosynthesis.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Lichen</span> acids can chemically weather rock by literally dissolving it. This provides crevices for the lichen to attach itself. Lichens can live on top of the rock (<b>epilithic</b>, epi = on top, and lith = stone), or they can be <b>endolithic</b> (within the stone). Within endolithic types, they can be <b>chasmolithic</b>, meaning they limit themselves to the fissures in the rocks and between the mineral grains, or they may be <b>cryptoendolithic</b>, meaning that the lichens grow within natural cavities in the rock. Finally, there is <b>euendolithic</b> lichens, and these are the toughest guys. They can dissolve the rock to the point of boring directly into the rock and creating its own cavities. Interestingly, the lichen will absorb much of the dissolved minerals, up to concentrations that would kill other organisms. This may prevent predation by making the lichen toxic to things that might eat it.</div>
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This ability to grow below the surface of a rock is exceptional. The photobiont must still be close enough to the surface to receive sunlight, but growing beneath the surface can protect the lichen from destructive forces of nature. Together with lichen acid protection from UV radiation and the lichens ability to survive extreme temperatures, the ability to grown inside rocks has implications for space travel. </div>
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We know that lichens can survive in space (<a href="http://biologicalexceptions.blogspot.com/2012/02/im-likin-lichen.html">I’m Likin’ The Lichen</a>) and growing inside rocks would protect them from re-entry temperatures, so could lichens have arrived on Earth from outer space? <b>Pangenesis</b> is the theory that life on Earth arriving from other planets, and lichens seem like a natural for this process. Unfortunately, pangenesis is most often considered with bacteria alone, and as a theory it has not got much to support it. But it is still an interesting proposition.</div>
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<span style="font-size: 11pt;">This rock is getting a good does of biological weathering. Tree roots,</span></div>
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<span style="font-size: 11pt;">lichens, and probably burrowing animals are all working to reduce </span></div>
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<span style="font-size: 11pt;">this noble boulder to gravel.</span></div>
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Growing inside rocks and dissolving the rock as needed promotes <b>weathering </b>breaking down of rock). Two type of weathering are brought about by lichen grown. Physical weathering comes primarily from turgor pressure. When the lichen takes up water (when it can get some), it swells and puts pressure on the fissures of the rock. Over time, this will lead to cracks and parts of the rock falling off.</div>
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There is also chemical weathering. This comes from the lichen acids dissolving the rock. Some of the minerals are mixed with the bits of rock that break off due to physical weathering and the organic material left over from dead lichens. All together, this makes soil. The process of <b>pedogenesis</b> (soil formation) is an important aspect of lichen growth. Making soil promotes the <b>succession</b> of bigger and more complex life forms, which then continue the weathering and soil formation. Look around you, all that dirt outside your window, deeper than you could dig, is there because of lichens started it all off – amazing. Lichens could be the most important player when it comes to human <b>terraforming</b> (terra = Earth and form = make like) another planet for future colonization.</div>
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<span style="font-size: 11pt;">Lichen growth on Easter Island. This ancient </span></div>
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<span style="font-size: 11pt;">statues can’t survive much Moai!</span></div>
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Not everything about weathering rock by lichens is good; consider their effects on stone statues. Some people say that the covering is protective, keeping the wind and sun from damaging the statue, but other say the chemical weathering promotes their breakdown. At Mount Rushmore, workers actively scrub the mountain to remove lichens and prevent the aging of Presidents Lincoln, Roosevelt, Jefferson, and Truman. How would you like to have that job, hanging off a cliff scrubbing out Theodore Roosevelt’s huge nostrils?</div>
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There is a strange dichotomy with lichens. They have arisen many times. They live thousands of years. They live in space, surviving radiation, extreme temperatures, and dryness. But lichens are very susceptible to pollution, it kills them or stops their growth. Lichens have billions of years of success behind them, but it took humans to find a way to kill them off. As such, we now use lichens as <b>indicator species</b>, to determine if pollution concentrations are affecting nature. They built our world, now maybe they can help us to save it.</div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Microiology&rft_id=info%3Adoi%2F10.1007%2Fs12275-011-0289-9&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Production+of+Anti-Helicobacter+pylori+metabolite+by+the+lichen-Forming+fungus+Nephromopsis+pallescens&rft.issn=&rft.date=2011&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Heng+Luo%2C+Yoshikazu+Yamamoto%2C+Hae-Sook+Jeon%2C+Yan+Peng+Liu%2C+Jae+Sung+Jung%2C+Young+Jin+Koh+and+Jae-Seoun+Hur&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CMicrobiology+%2C+Biochemistry">Heng Luo, Yoshikazu Yamamoto, Hae-Sook Jeon, Yan Peng Liu, Jae Sung Jung, Young Jin Koh and Jae-Seoun Hur (2011). Production of Anti-Helicobacter pylori metabolite by the lichen-Forming fungus Nephromopsis pallescens <span style="font-style: italic;">Journal of Microiology</span> DOI: <a href="http://dx.doi.org/10.1007/s12275-011-0289-9" rev="review">10.1007/s12275-011-0289-9</a></span>
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<span style="font-size: 11pt;">For more information on lichen products, biological weathering, or pedogenesis, see:</span></div>
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<span style="font-size: 11pt;">Lichen acids – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.gaiachem.com/lichen.html">http://www.gaiachem.com/lichen.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://lichens.science.oregonstate.edu/antibiotics/lichen_antibiotics.htm">http://lichens.science.oregonstate.edu/antibiotics/lichen_antibiotics.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.countrysideinfo.co.uk/fungi/lichens.htm">http://www.countrysideinfo.co.uk/fungi/lichens.htm</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.uni-graz.at/~grubem/treasure.pdf"><span style="font-style: normal;">www.uni-graz.at/~grubem/treasure.pdf</span></a></span></cite></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.ars.usda.gov/is/ar/archive/jan01/lichen0101.pdf"><span style="font-style: normal;">www.ars.usda.gov/is/ar/archive/jan01/</span><b><span style="font-style: normal;">lichen</span></b><span style="font-style: normal;">0101.pdf</span></a></span></cite></div>
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<span style="font-size: 11pt;"><a href="http://www.thebls.org.uk/content/chemical.html">http://www.thebls.org.uk/content/chemical.html</a></span></div>
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<span style="font-size: 11pt;">Biological weathering –</span></div>
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<span style="font-size: 11pt;"><a href="http://www.geography4kids.com/files/land_weathering.html">http://www.geography4kids.com/files/land_weathering.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.lad.wur.nl/UK/Research/LAPSUS/Modules/Biological/">http://www.lad.wur.nl/UK/Research/LAPSUS/Modules/Biological/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.geolsoc.org.uk/gsl/pid/3568;jsessionid=8C3F5253340E02BEDE9FE9C0234D4A0D">http://www.geolsoc.org.uk/gsl/pid/3568;jsessionid=8C3F5253340E02BEDE9FE9C0234D4A0D</a></span></div>
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<span style="font-size: 11pt;"><a href="http://mc2.vicnet.net.au/home/conserv/web/biolog.html">http://mc2.vicnet.net.au/home/conserv/web/biolog.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.soils.wisc.edu/courses/SS325/weathering.htm#stages">http://www.soils.wisc.edu/courses/SS325/weathering.htm#stages</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.pbs.org/wnet/nature/lessons/breaking-it-down/activities/1700/">http://www.pbs.org/wnet/nature/lessons/breaking-it-down/activities/1700/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://alex.state.al.us/lesson_view.php?id=24146">http://alex.state.al.us/lesson_view.php?id=24146</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.okaloosa.k12.fl.us/technology/WOWLessons/WaltsYouveBeenWeathered.htm">http://www.okaloosa.k12.fl.us/technology/WOWLessons/WaltsYouveBeenWeathered.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://ethemes.missouri.edu/themes/1318">http://ethemes.missouri.edu/themes/1318</a></span></div>
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<span style="font-size: 11pt;">Pedogenesis – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.physicalgeography.net/fundamentals/10u.html">http://www.physicalgeography.net/fundamentals/10u.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.anbg.gov.au/lichen/ecology.html">http://www.anbg.gov.au/lichen/ecology.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.wormdigest.org/content/view/222/2/">http://www.wormdigest.org/content/view/222/2/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.eoearth.org/article/Soil">http://www.eoearth.org/article/Soil</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;">files.dnr.state.mn.us/education.../<b>activities</b>/.../<b>lichens</b>_studyguide.pdf</span></cite></div>
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<span style="font-size: 11pt;"><a href="http://www.concord.org/~btinker/gaiamatters/investigations/lichens/classactivities.html">http://www.concord.org/~btinker/gaiamatters/investigations/lichens/classactivities.html</a></span></div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1tag:blogger.com,1999:blog-8136765635696545893.post-39679599294166574762017-09-28T06:00:00.000-04:002017-09-28T06:00:08.300-04:00I’m Likin’ The Lichen<br />
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<span style="font-family: "cambria"; font-size: 12pt;">Biology Concepts – <u>symbiosis</u>, <u>mutualism</u>, <u>lichens</u></span></div>
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<span style="font-size: 11pt;">The lycan is a subject better relegated a cryptozoology </span></div>
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<span style="font-size: 11pt;">blog. Along with the Loch Ness Monster, vampires, and </span></div>
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<span style="font-size: 11pt;">the Easter Bunny, cryptids are those animals for </span></div>
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<span style="font-size: 11pt;">whom there is little or no solid evidence, yet the search </span></div>
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<span style="font-size: 11pt;">for them by some devotees continues.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">A current movie craze has been to replace werewolves with lycans, animals that can control there physical changes to wolf, and can survive under difficult conditions. I know of another organism that has even greater powers, but wouldn’t make a great movie monster – they don’t move and are very slow<span style="background-color: white;"> </span><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">growing.</span></span></div>
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<span style="font-family: "cambria"; font-size: 12pt;"><b>Lichens</b> (not lycans) are some of the most intriguing species on Earth, and may very well be the most amazing organisms off Earth as well. Lichens don’t necessarily break a lot of biological rules; they just refuse to acknowledge that our rules apply to them. They write their own rulebook, and humans can’t come close to playing by their rules. They make us look like such wimps. In lichen gym class, we wouldn’t be picked last - we wouldn’t picked at all.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Lichens are symbiots of two completely unrelated organisms; one is the mycobiont, which is always a fungus. The other component is the <b>photobiont,</b> and can be either a green algae or a cyanobacteria. The fungal partner of the lichen makes up about 80% of the mass, but the algae or bacterial component is photosynthetic. Therefore, when they become a mutualistic symbiot, the mycobiont provides a structure and a foothold to a surface, while the photobiont supplies energy through <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">photosynthesis.</span> </span></div>
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<span style="font-size: 11pt;">Lichens provide food for many animals. For instance, the </span></div>
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<i><span style="font-size: 11pt;">Cladina Stellaris</span></i><span style="font-size: 11pt;"> grows in the desolate Arctic. It provides </span></div>
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<span style="font-size: 11pt;">food for the resident reindeer, who we know from past posts </span></div>
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<span style="font-size: 11pt;">can disconnect its biological clock and feed all through the </span></div>
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<span style="font-size: 11pt;">day. The reindeer must be particular though, because it will </span></div>
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<span style="font-size: 11pt;">take the reindeer lichen decades to recover from grazing, </span></div>
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<span style="font-size: 11pt;">since it grows only 3-5 mm each year.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">This is the first exception when dealing with lichens – what are they? They certainly aren’t plants, since they contain a fungal element and not plant element. But they aren’t fungi, since they also contain a bacterial (the cyanobacteria) or protist element (the algae). They are kings in search of a kingdom. Just like Lady Gaga, they defy classification as normal life!</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Fungi are decomposers; they break down organic materials to produce nutrients and carbohydrates. But in the lichen, the photobiont produces glucose by photosynthesis, so there is no need for the fungi to decompose for energy. The lichen stores most of its soluble carbohydrate as sugar alcohols, which are made by the fungal component from the algae/cyanobacteria-produced glucose. Therefore, the fungus provides a carbohydrate storage mechanism as well as a structure. These aspects give lichens the ability to live where neither the fungus nor the algae could live on its own.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The second amazing aspect of the lichen symbiosis is that the lichen doesn’t look like either the fungus or the algae that makes it up. It also doesn’t look like a mix of the two. The lichen creates a whole new morphology, with the photobiont housed below a layer of the modified fungus. In the case of lichens, you add 2 + 2 and get a Chevy.</span></div>
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<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-size: large;">The</span><span style="font-family: "cambria"; font-size: 12pt;"> thallus is the body of the lichen (latin for “green shoot”). In most cases, the thallus is a layer of the fungus, called a cortex, with the photobiont house just below the cortical layer. Enough light still reaches the algae or cyanobacteria in order to make photosynthesis possible. Below the photobiont layer is the medulla, and can include a stringy (<b>hyphal</b>) fungus layer or maybe just the gelatinous photobiont. Finally, some lichens will have a lower cortex layer of fungus as well. The take home message is that neither the fungus nor the algae or cyanobacteria take on any of these forms UNLESS they are part of a lichen – it is a completely different structure. </span></div>
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<span style="font-size: 11pt;">Not every lichen has a lower cortex layer, but almost all </span></div>
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<span style="font-size: 11pt;">have the top cortical layer of tough fungal material. This </span></div>
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<span style="font-size: 11pt;">layer protects the lichen from predation and dessication </span></div>
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<span style="font-size: 11pt;">(it does nether spectacularly well). The photobiont lives </span></div>
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<span style="font-size: 11pt;">primarily in the subcortical symbiont layer, while the </span></div>
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<span style="font-size: 11pt;">medulla is spongy and has many fungal filaments. The </span></div>
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<span style="font-size: 11pt;">rhizine connects the lichen to its substrate, but many </span></div>
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<span style="font-size: 11pt;">lichens are <span class="st">erhizinate</span>, they do not have rhizines.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The mycobiont is the more flexible of the two components; literally thousands of different fungi can act as the mycobiont. On the other hand, only 100 or so different photobionts exist. Most common of these are of the species <i>Trebouxia</i>. They are green algae which rarely live on their own, they have become specialized for symbiotic life as a lichen.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The combination of these two components yields the over 17,000 different lichens that have been identified. The combinations are also flexible, a lichen may use different photobionts during its life, and identical lichen types may use different photobionts even within the same general area.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The combinations of decomposer and autotroph that make up lichens are hearty and diverse. Fully 8% of the Earth’s surface is covered with lichens, not bad for something so small. More amazing is that lichens can survive in places that support almost no other life. Lichens and endolithic bacteria are only living things in the McMurdo Dry Valleys of Antarctica, as well as the Atacama desert of Chile, often called the two driest places on Earth (I think they forgot about Lynchburg, TN). </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The McMurdo Valleys (4,800 sq. km) are a cold desert environment (<a href="http://biologicalexceptions.blogspot.com/2012/02/water-water-everywhere-but.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Water, Water, Everywhere</span></a>). They are almost ice and snow free, even though they are on the frozen continent of Antarctica. Less than 200 mm (8 in) of precipitation is available each year, and most of this is from summer glacier melt.</span></div>
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<span style="font-size: 11pt;">The Atacama Desert in Chile is a desolate wasteland, </span></div>
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<span style="font-size: 11pt;">no offense to any inhabitants. It probably has its </span></div>
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<span style="font-size: 11pt;">nice parts too. Parts of the desert have had no</span></div>
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<span style="font-size: 11pt;">recorded rainfall..... ever. This leads to some </span></div>
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<span style="font-size: 11pt;">interesting formations, like these geometric salt </span></div>
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<span style="font-size: 11pt;">patterns, very appropriate for this series of posts.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;"> The average rainfall in the entire Atacama Desert is even less, only about 1mm (0.04 in) per year, and many weather stations have never recorded any precipitation at all.</span><span style="font-family: "cambria"; font-size: 12pt;"> The lichens survive on the water vapor that reaches them from the coastal fog,which comes from 150 km (80 miles) and a mountain range away. Interestingly, an extreme Antarctic cold front brought 80 cm (31.5 in) of snow to the plateau in July of 2011! This was enough to bring wildflowers to the Atacama, in places they had never been seen before.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Despite (or perhaps because of) these arid environments, lichens are the major form of life in the Atacama Desert and McMurdo Valleys. Most organisms cannot survive a loss of 20% moisture, but lichens can do just fine when 90% dehydrated. While their growth may be retarded, they quickly make up for it by absorbing up to 35x their mass in water when it is available. Lichens dry out slowly because of the dense cortex of fungus on the outside, so they can still photosynthesize despite long arid periods.</span></div>
<div class="MsoNormal">
<span style="font-size: large;"><br />
</span></div>
<div class="MsoNormal">
<span style="font-family: "cambria"; font-size: 12pt;">Even more exceptional, the lichen symbiot is less than 50% water, even on a good day. Mushrooms are 92% water, and algae or bacteria are typically 96% water, but when you put them together as a lichen, their normal water content is some 40-45% lower. This is how the lichen can live in places that would not support either of its components on their own – amazing. </span></div>
<div class="MsoNormal">
<span style="font-size: large;"><br />
</span></div>
<div class="MsoNormal">
<span style="font-family: "cambria"; font-size: 12pt;">The deserts, both cold and hot, allow the lichens to show off another of their skills. Lichens can withstand extreme temperatures and wild swings in temperature. Scientists keep thinking up new ways to torture them. Lichens survived a bath in liquid nitrogen at <sup>-</sup>195 ˚C. Not satisfied that they had been treated harshly enough, European Space Agency scientists strapped some lichens to a rocket and exposed them to the cold and radiation of outer space for 14.6 days. Cold, hot (shielded re-entry), vacuum, UV, cosmic rays – the lichens survived just fine. Because of this will to live, <b>exobiologists</b> (scientists who study what life on other planets might be like) study lichens as a model alien life form or as an organism with which we might seed other planets.</span><br />
<br />
<span style="font-family: "cambria"; font-size: large;">
</span></div>
<div class="MsoNormal">
<span style="font-family: "cambria"; font-size: 12pt;">Lichens (or something similar to them) are likely to be found
on other planets, but they also may affect other forms of life off Earth. A
<a href="http://online.liebertpub.com/doi/abs/10.1089/ast.2012.0828">recent study by performed in Italy and the UK</a> has shown that the few animal types (rotifers, nematodes)
that are able to survive dessication as lichens can are influenced greatly by
their environment. They may have different ways to survive drought, but statistical
modeling shows that the type of lichen they are found in has more to do with
their survival in drought or even in space than their own tolerance mechanisms.</span>
</div>
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX6SUK5KE7g7qTouREvLqC4a8N7gOGWBRwF7SAJc_9Hf_WvQLg0a6Y7buWqgFwxOdnGWGwyOH-9gmtmfAYp6EhUR1SVfrqOWidHcKM2tt7OJNzWcCY5b6Mx_YiTO7FJtznYwUANMg6VyHS/s1600/lichenometry.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjX6SUK5KE7g7qTouREvLqC4a8N7gOGWBRwF7SAJc_9Hf_WvQLg0a6Y7buWqgFwxOdnGWGwyOH-9gmtmfAYp6EhUR1SVfrqOWidHcKM2tt7OJNzWcCY5b6Mx_YiTO7FJtznYwUANMg6VyHS/s1600/lichenometry.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">Lichenometry is the art and science of investigating </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">how long a surface has been exposed. For example, </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">moraines are gatherings of stones at the edges of </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">glaciers. How long has it been since the glacier receded </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">from that spot? Lichens grow at a predictable rate given </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">a known environment, so measuring the size of a lichen </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">will give good estimate of how long the surface has been </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">available to be lichenized (just made up that word).</span></div>
</td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="font-family: "cambria"; font-size: 12pt;">As a result of the poor environments where lichens can be found (although they also grow just fine in temperate areas- just look outside your front door), lichens are the slowest growing life forms on Earth. <i>Usnea sphacelata</i>, which looks like a small forest of bonsai, grows about 0.01-1 mm per year. <i>Usnea</i> can only grow on about 120 days per year, but they live a very long time. An age of 200 years is not unusual, the record is about 4500 years. </span></div>
<div class="MsoNormal">
<span style="font-size: large;"><br />
</span></div>
<div class="MsoNormal">
<span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-size: large;">In</span><span style="font-family: "cambria"; font-size: 12pt;"> a defined area with a defined weather pattern, lichens may grow at a very slow rate, but it is a very consistent rate. This predictability makes them good for dating other structures, a process called <b>lichenometry</b>. For instance, lichens can be use to estimate how long a rock face has been exposed by a retreating glacier. Once the rock is uncovered, lichens will soon colonize it and grow at a consistent rate. Once you know the size of the lichen, identify the type of lichen, and know its growth rate for that area, an age for the exposure can be calculated.</span></div>
<div class="MsoNormal">
<span style="font-family: "cambria"; font-size: 12pt;"><br />
</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Next week we will talk more about the amazing properties and abilities of lichens, but one last tidbit for today. For anyone who has read Peter Rabbit or Benjamin Bunny to their child, Beatrix Potter is a familiar name. Before becoming a famous author, Beatrix made a living by illustrating other author’s books and doing some scientific illustrations. She was an outdoorsy girl, and her pictures of lichens led her to study them on her own. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0qY7SyoY1kKSSS-lkzZ9-ixzYnetETu3iggYNG1-_7VNgMFzd9aPQpmc8XDmkoM-LmA8H2VpGX5AvTkw-n0Z1-RIB7XPwk13emEcTlPYKxK4Ay1FtscMdw7BZNQaJ5WAkMQgkTaurAVQg/s1600/beatrix-potter.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi0qY7SyoY1kKSSS-lkzZ9-ixzYnetETu3iggYNG1-_7VNgMFzd9aPQpmc8XDmkoM-LmA8H2VpGX5AvTkw-n0Z1-RIB7XPwk13emEcTlPYKxK4Ay1FtscMdw7BZNQaJ5WAkMQgkTaurAVQg/s320/beatrix-potter.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">Beatrix Potter wrote more than 20 childrens classics; the </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">illustrations were her own and are perhaps more iconic than </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">her prose. But she started out working on lichens, and was a </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">devout “Schwendenerist,” a follower of Simon Schwendener’s </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">idea of lichen symbiosis. I got the chance to collaborate with </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">one of Simon’s distant relatives a few years ago. Hi Reto!</span> </td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">While the dual hypothesis of lichens had already been put forth by Simon Schwendener, it was not well received in England. Potter used microscopy and her drawings to generate evidence for Schwendener’s hypothesis. However, she was not a scientist, and worse, she was a woman – so she couldn't present her evidence to the botanists of her time. Her uncle was Sir Henry Roscoe, the eminent scientist who developed the first flashbulbs for photography (along with another scientist named Bunsen – name sound familiar?). He supported her and read her papers into the scientific record, but she could never make name for herself as a scientist in that environment, so she turned to writing. It was a lucky thing for us all – a world without Flopsy and Mopsy is too horrible to imagine.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Astrobiology&rft_id=info%3Adoi%2F10.1089%2Fast.2012.0828&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Long-Term+Survival+of+Microscopic+Animals+Under+Desiccation+Is+Not+So+Long&rft.issn=1531-1074&rft.date=2012&rft.volume=12&rft.issue=9&rft.spage=863&rft.epage=869&rft.artnum=http%3A%2F%2Fonline.liebertpub.com%2Fdoi%2Fabs%2F10.1089%2Fast.2012.0828&rft.au=Fontaneto%2C+D.&rft.au=Bunnefeld%2C+N.&rft.au=Westberg%2C+M.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CCell+Biology%2C+Chemical+Biology%2C+Evolutionary+Biology%2C+Microbiology+%2C+Protistology%2C+Zoology">Fontaneto, D., Bunnefeld, N., & Westberg, M. (2012). Long-Term Survival of Microscopic Animals Under Desiccation Is Not So Long <span style="font-style: italic;">Astrobiology, 12</span> (9), 863-869 DOI: <a href="http://dx.doi.org/10.1089/ast.2012.0828" rev="review">10.1089/ast.2012.0828</a></span>
<br />
<span style="font-size: 11pt;">For more information or classroom activities on lichens, exobiology, or lichenometry, see:</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">Lichens - </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.lichen.com/biology.html">http://www.lichen.com/biology.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.ucmp.berkeley.edu/fungi/lichens/lichens.html">http://www.ucmp.berkeley.edu/fungi/lichens/lichens.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.backyardnature.net/lichens.htm">http://www.backyardnature.net/lichens.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.earthlife.net/lichens/intro.html">http://www.earthlife.net/lichens/intro.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://herbarium.usu.edu/fungi/funfacts/lichens.htm">http://herbarium.usu.edu/fungi/funfacts/lichens.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.countrysideinfo.co.uk/fungi/lichens.htm">http://www.countrysideinfo.co.uk/fungi/lichens.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.concord.org/~btinker/gaiamatters/investigations/lichens/classactivities.html">http://www.concord.org/~btinker/gaiamatters/investigations/lichens/classactivities.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://serc.carleton.edu/sp/mnstep/activities/19759.html">http://serc.carleton.edu/sp/mnstep/activities/19759.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://gis.nacse.org/lichenair/?page=lessons">http://gis.nacse.org/lichenair/?page=lessons</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.concord.org/~btinker/gaiamatters/investigations/lichens/trip.html">http://www.concord.org/~btinker/gaiamatters/investigations/lichens/trip.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">Exobiology – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/">http://www.chem.duke.edu/~jds/cruise_chem/Exobiology/</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.astrobiology.com/exobiology.html">http://www.astrobiology.com/exobiology.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://cmex.ihmc.us/sitecat/sitecat2/exobiolo.htm">http://cmex.ihmc.us/sitecat/sitecat2/exobiolo.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://adsabs.harvard.edu/abs/2007AsBio...7..443S">http://adsabs.harvard.edu/abs/2007AsBio...7..443S</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.theregister.co.uk/2005/11/09/lichens_space_mars/">http://www.theregister.co.uk/2005/11/09/lichens_space_mars/</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.oasi.org.uk/Archive/Misc/Exobiology.htm">http://www.oasi.org.uk/Archive/Misc/Exobiology.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">Lichenometry – </span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www-staff.lboro.ac.uk/~gydjg2/baffin/3_lichen.htm">http://www-staff.lboro.ac.uk/~gydjg2/baffin/3_lichen.htm</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.eric.ed.gov/ERICWebPortal/search/detailmini.jsp?_nfpb=true&_&ERICExtSearch_SearchValue_0=EJ401381&ERICExtSearch_SearchType_0=no&accno=EJ401381">http://www.eric.ed.gov/ERICWebPortal/search/detailmini.jsp?_nfpb=true&_&ERICExtSearch_SearchValue_0=EJ401381&ERICExtSearch_SearchType_0=no&accno=EJ401381</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.primaryresearch.org/stonewalls/nylund/index.php">http://www.primaryresearch.org/stonewalls/nylund/index.php</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p009.shtml">http://www.sciencebuddies.org/science-fair-projects/project_ideas/Geo_p009.shtml</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.geo.arizona.edu/palynology/geos462/13lichenometry.html">http://www.geo.arizona.edu/palynology/geos462/13lichenometry.html</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://geoggeol.wku.edu/awulff/California1/Lichenometry.html">http://geoggeol.wku.edu/awulff/California1/Lichenometry.html</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://rockglacier.blogspot.com/2008/10/lichenometry.html">http://rockglacier.blogspot.com/2008/10/lichenometry.html</a></div>
<div style="margin: 0.1pt 0in;">
<a href="http://historyofgeology.fieldofscience.com/2010/08/botany-for-geologists-lichenometry.html">http://historyofgeology.fieldofscience.com/2010/08/botany-for-geologists-lichenometry.html</a></div>
<cite><span style="font-family: "cambria"; font-size: 12pt;"><a href="http://www.geog.uvic.ca/dept2/faculty/smithd/.../06%20Geog%20477.pdf"><span style="font-style: normal;">www.geog.uvic.ca/dept2/faculty/smithd/.../06%20Geog%20477.pdf</span></a></span></cite>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com0tag:blogger.com,1999:blog-8136765635696545893.post-2374405751702045162017-09-21T06:00:00.000-04:002017-09-21T06:00:00.710-04:00Water, Water Everywhere, But….<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Biology concepts – <u>symbiosis</u>, <u>mutualism</u>, <u>water storage </u></span></div>
<div style="margin: 0.1pt 0in;">
<u><span style="font-family: "cambria"; font-size: 12pt;"><span style="text-decoration: none;"><br />
</span></span></u></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIoO9bokdRTE2C8p8xwP0RPxWHKkYlPAbeAAsjy5OkExRKo2TA2ZKVbXS7w_jeQqRiaB84u1Ye97cstTGN-VC9uPoqu02O4xMgofeWckkI4Y5TqYxObCLTBNnadwQ0hIo2uC45-afTwJj8/s1600/gobi.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjIoO9bokdRTE2C8p8xwP0RPxWHKkYlPAbeAAsjy5OkExRKo2TA2ZKVbXS7w_jeQqRiaB84u1Ye97cstTGN-VC9uPoqu02O4xMgofeWckkI4Y5TqYxObCLTBNnadwQ0hIo2uC45-afTwJj8/s320/gobi.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">“Gobi” means desert in Ural-Altaic,</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">so when you say, “Gobi Desert,” you</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">are really being redundant.</span></div>
</td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Sometimes the places with the most water are the most lifeless areas. Everyone thinks of sand and heat, but Lawrence of Arabia wouldn’t even recognize most <b>biological deserts</b>.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">The term biological desert is misleading, since places like the Gobi Desert in Asia support over 600 species of plants and hundreds of animal species, vertebrate and invertebrate. Death Valley in the USA has over 100 plants species; it could hardly be called dead! A biological desert has less to do with the climate and more to do with the adaptability of organisms to adverse conditions of oxygen, salt, water, light, or too often - pollution.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Take for instance the South Pacific Gyre. This area of about 34 million square kilometers (10 million sq. miles) has very little life in the <b>pelagic zone</b> (the below the surface waters to just above the sea floor). In the last posts we learned why water and salts are crucial for life, and the extreme evolutionary adaptations that have occurred in many organisms in order to conserve body water and maintain safe salt levels. But here we are in the ocean – water everywhere, salt everywhere, but almost nothing lives in the gyre.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4HILF45ZKcWbDJP94DQZkrqrliLZIylOsolWgjsUgXCMnkwmLM5nXfvcdf2-WtwtdcbkKBCtktUyjAt-YTkBEUVMJzNXKrKKSYiGcmDnvPlqE9C8nZ6hD2L6DfC6tWwTsEpIgjuk8EeSI/s1600/gyres1.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4HILF45ZKcWbDJP94DQZkrqrliLZIylOsolWgjsUgXCMnkwmLM5nXfvcdf2-WtwtdcbkKBCtktUyjAt-YTkBEUVMJzNXKrKKSYiGcmDnvPlqE9C8nZ6hD2L6DfC6tWwTsEpIgjuk8EeSI/s320/gyres1.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">The north and south Pacific gyres represent </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">a huge portion of the Earth’s surface, and </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">these are relatively life free areas, the largest </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">deserts on Earth.</span></div>
</td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">The reason for this paucity of life has more to do with nutrients than with water or salt. Because the current moves counter-clockwise, the center of the gyre is isolated from the upwelling of nutrients from the ocean floor, and the winds can’t help to churn the waters. Even if they could, it would help little. The waters of the gyre are rigidly layered due to salt and temperature differences (<b>stratification</b>, <a href="http://biologicalexceptions.blogspot.com/2012/02/i-am-your-density.html"><span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); color: black;">I Am Your Density</span></a>), so nutrients find it difficult to travel to the surface from below. Adding to the problem, there is little landmass in the South Pacific, so windblown organic material and terrestrial runoff are limited. Nutrients are coming from neither above nor from below.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">With limited nutrients, there is a ceiling to the amount of primary productivity of <b>phytoplankton</b> (phyto = plant, and planktos = wandering in Greek) that can take place. Fewer producers means that few primary consumers can be supported, and so forth up the food chain. Little life on the surface means few nutrients drop to the ocean floor (waste and dead organisms), and so on.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">The ocean gyres have little upwelling if nutrients </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">and therefore little plankton production. The bad </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">news - with global climate change, the gyre-related </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">low productivity zones are growing in size. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Strangely enough, the lack of producers in the gyre has benefited humans in at least one aspect. The chlorophyll of the producers changes the color of the ocean, and this affects the trapping of heat and the wind currents. With a loss of living things in the North pacific gyre, a 2010 study states that typhoon formation has decreased in this region by more than 70%............Don’t get too excited, global surveying also says that the biological deserts of the gyres are growing much faster than global warming models would predict. As they grow, global productivity will be reduced, and that can’t be good for any of us.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">We don’t make things any easier by letting chemicals run into the oceans either. Man made dead zones from increased nitrogen and phosphorous. These nutrients are needed for growing phytoplankton, but you can have too much of a good thing. The overgrowth of phytoplankton and algae in these areas, along with the decomposers they support, deplete O<sub>2</sub>. The result is that there is no oxygen left for succession organisms, so larger animals cannot live there (neither can the plankton or algae after a while). </span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-CvYJIBT264mBniiS6npCtyMY8uv-gWMh6Md2UKdGgfwrq3249j1PRzmNxiA9QX7UZaTUjZO9kUaUMLkfGoAo-kFKOG2SBUItC3yQyxCPePRo0UaUVz1Cxvz4ON1G0TJTIN-UDAIT2HSk/s1600/Dead_Zones.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="187" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-CvYJIBT264mBniiS6npCtyMY8uv-gWMh6Md2UKdGgfwrq3249j1PRzmNxiA9QX7UZaTUjZO9kUaUMLkfGoAo-kFKOG2SBUItC3yQyxCPePRo0UaUVz1Cxvz4ON1G0TJTIN-UDAIT2HSk/s320/Dead_Zones.jpg" width="320" /></a></td></tr>
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<span style="font-family: "cambria"; font-size: 11pt;">Man made dead zones correspond to areas of </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">runoff from sprayed fields. For instance, the estuary </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">of the Mississippi River in the Gulf of Mexico forms </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">the second largest man made dead zone in the world </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">each summer. Not to be outdone, the Baltic Sea dead </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">zone in Northern Europe is the largest, and it is </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">present all year round.</span> </td></tr>
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<span style="font-family: "cambria"; font-size: 12pt;">So the gyres are “almost dead” zones, and some polluted estuaries are considered dead zones. What about a body of water with dead in its name, the Dead Sea? At 423 meters (1388 feet) below sea level, the Dead Sea is officially the lowest body of water on Earth. Water flows into it, but not out of it, so all the salts and minerals just accumulate. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The temperature of the desert surrounding the Dead Sea is warm enough that evaporation plays a factor in increasing the salinity and mineral content of the remaining water. Only certain types of bacteria and algae can survive in the 33.7% saline waters (~8.6 x the salinity of the Mediterranean Sea).</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;"> <i>Dunaliella salina</i> algae are particularly abundant in the Dead Sea after the rainy season. These green algae produce antioxidant carotenoids to protect themselves from the intense sun exposure of the Jordan Rift Valley as well as huge amounts of glycerol (a three carbon carbohydrate) to counteract the osmotic pressure which would otherwise move all the freshwater out of the algal cells. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The algae is a good food source for halophilic (salt-loving) bacteria. However, during dry years, both the alga and bacteria are present in much lower numbers. But isn’t just the high salt that prevents larger plants and animals from living in the Dead Sea. The minerals that accumulate, such as magnesium chloride, calcium chloride, magnesium bromide, and calcium sulfate, are toxic to animals that drink the water. Fish from the freshwater feeders of the Dead Sea sometimes swim into the mineral-laden waters and are killed almost instantly.</span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgu8x4c1cYYhRzPTB24eqBC4l1uQHzXrUytMrKyJ-X3fgGzIu8RM0sqoq2XVhyphenhyphenfYAHavrL0zB9wIJNdzm6aHY1Abn1_gpoFNGtbwkd4c1zlMjpQ6bLeCRbvUMNLTPEytuKhgsRVMPCJ3xey/s1600/Dead_Sea_rocks_covered_with_salt_kg_n101900w.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgu8x4c1cYYhRzPTB24eqBC4l1uQHzXrUytMrKyJ-X3fgGzIu8RM0sqoq2XVhyphenhyphenfYAHavrL0zB9wIJNdzm6aHY1Abn1_gpoFNGtbwkd4c1zlMjpQ6bLeCRbvUMNLTPEytuKhgsRVMPCJ3xey/s320/Dead_Sea_rocks_covered_with_salt_kg_n101900w.jpg" width="320" /></a></td></tr>
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<span style="font-family: "cambria"; font-size: 11pt;">The Dead Sea has receded a mile in the past twenty </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">years, and environmentalists warn it could be </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">completely gone by 2050. As it recedes, it leaves </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">salt on the rocks after the water evaporates.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The exception to this is the recently discovered freshwater springs that also feed the Dead Sea. Along the sea bottom near these vents lives a multitude of <b>Archaea</b> (often called extremophiles) that used to be classified as bacteria, but are now known to be a different kingdom of life. Spreading along the seafloor, mats of Archaea form <b>biofilms</b>, previously unknown in the Dead Sea.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The Great Salt Lake in Utah is similar to the Dead Sea biologically, but the lower salinity (some places are 5% salt, while others are 25 %; a railroad causeway has separated it into a more saline north arm and less saline south arm) allows more types of organisms to thrive in the water. Still no fish, but more types of algae, as well as some brine shrimp and brine flies. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Surprisingly, there is abundant flora and fauna <u>around</u> both the Great Salt Lake and the Dead Sea. The Jordan Rift Valley boasts camels, leopards, and ibexes, as well as fig trees and the rose of Jericho. In the western hemisphere, the Great Salt Lake has millions of shore birds, mostly fed by the 100 billion brine flies that hatch each summer. It is just the exception that here you have to move away from the water to find the life.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The above two examples indicate areas that have a lot of water, but too much salt for it to be useful. There is another place on Earth that has plenty of H<sub>2</sub>O, but not enough liquid water to support much life – does that make sense?</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Antarctica. It is hard to believe that with all that ice, miles thick in some places, there is not enough free water to keep plants and animals alive, but in many parts of the continent, that is the case.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">McMurdo Station is the largest community on </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Antarctica, if you don’t count the penguins. It is </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">located near the McMurdo Dry Valleys, the driest </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">places on Earth. </span><span style="font-size: 11pt;">This is due to the katabatic winds.</span></div>
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<span style="font-size: 11pt;">Cold air is more dense, and is pulled downhill. The </span></div>
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<span style="font-size: 11pt;">wind can reach speeds of 200 mph, and as it warms, </span></div>
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<span style="font-size: 11pt;">it evaporates all the moisture on the ground and in the air.</span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Some areas of Antarctica do support a little life; two vascular plants exist on the frozen continent, hair grass (<i>Deschampsia antarctica</i>) and the pearlwort (<i>Colobanthus quitensis</i>). These plants only grow on the west coast peninsula. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">In the McMurdo Dry Valleys, east of McMurdo Station and the Ross ice sheet, almost nothing grows. There are hypersaline lakes here that put the Dead Sea to shame, including the Don Juan Pond that is 18x the salinity of the ocean. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">There are no vertebrate animals in the valleys; microbes make up all the biology there. In all of Antarctica, only 67 species of insect are found, and most of these live as parasites on penguins. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The exception is the wingless midge (<i>Belgica antarctica</i>). At an average of 6 mm long, this fly is the largest purely terrestrial and year-round animal on the entire continent (penguins only live on the continent for part of the year). This flightless fly relative lives in algae mats, on rocks, and in the mud… just about anywhere it wants to. There are no competitors on Antarctica; this walking fly reigns supreme!</span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3cmvr_BwbMWoHrRWSUteqa1oQyHi5WB9NrjiEDMwZ5aK4lXwwOWoQTdeZ3o9Q92l1NHz5QaM5p_H_3GvOmeF_Uv2fD-QLvdv2BBnEBlvm5Xnaxi5ezzZbjhuYywO5hyphenhyphenwzxO7ff8VV1U_I/s1600/Belgica.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3cmvr_BwbMWoHrRWSUteqa1oQyHi5WB9NrjiEDMwZ5aK4lXwwOWoQTdeZ3o9Q92l1NHz5QaM5p_H_3GvOmeF_Uv2fD-QLvdv2BBnEBlvm5Xnaxi5ezzZbjhuYywO5hyphenhyphenwzxO7ff8VV1U_I/s320/Belgica.jpg" width="240" /></a></td></tr>
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<i><span style="font-family: "cambria"; font-size: 11pt;">Belagica</span></i><span style="font-family: "cambria"; font-size: 11pt;"> is well adapted to life in Antarctica. It is </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">black to absorb heat, and it is wingless so it won’t </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">be blown out to sea by the strong winds. It has a </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">short egg laying time and adult life span so that it </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">can complete its life cycle in the highly variable </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">summer season.</span> </td></tr>
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<span style="font-family: "cambria"; font-size: 12pt;">Other adaptations allow <i>B. antarctica</i> to thrive in this harsh environment. While the vast majority of plants and animals die with a relatively low level of dehydration (5-25%), these midges can survive a 70% water loss event - I suspect they can’t expectorate! In the winter…… WINTER? Isn’t it always winter there? Well, no; there is a colder season....the midge can react to winter by dehydrating and then coming back to life in the spring. Something like having a piece of beef jerky moo after you start salivating on it. Amazing.</span><br />
<br />
<span style="font-family: "cambria"; font-size: 12pt;"><a href="http://www.springerlink.com/content/h628988jx7774716/">Recent evidence</a> shows just how adapted <i>B. antarctica</i> is for the dehydration. The midge has one genetic response to thermal stress, whether it be hot or cold. They turn off some pathways and increase glucose metabolism pathways.</span><br />
<br />
<span style="font-family: "cambria"; font-size: 12pt;">But in dehydration, it has different responses to different patterns of dessication. If it is a rapid dehydration, glucose metabolism pathways are up regulated, but if it is slow and steady, a whole different set of pathways are upregulated, including those for different osmoprotectant molecules (trehelose and proline).</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The dry valley temperatures (-10˚C to -51˚C) could easily cause havoc with the midge’s protein function, including the pathways that protect it from dehydration stress. <b>Heat shock proteins</b> help to stabilize protein function in temperature extremes, usually they are expressed (transcribed from DNA and translated from mRNA) for short periods of time, only when there is an abnormal event. But Belgica’s heat shock proteins are expressed all the time. This is a huge energy investment, and an investment that few animals are willing to make. But in areas with too much salt or too little water, sacrifices must be made. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Next time we will talk about one of the greatest exceptions in biology, an organism that can live in the Atacama Desert, the Jordan Rift Valley, the Great Salt Lake, and even at Antarctica. It's not a bacteria, not a fungus, not a plant, not an animal – this is one heck of an exception.</span></div>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=J+Comp+Physiol+B&rft_id=info%3Adoi%2F10.1007%2Fs00360-012-0707-2&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Expression+of+genes+involved+in+energy+mobilization+and+osmoprotectant+synthesis+during+thermal+and+dehydration+stress+in+the+Antarctic+midge%2C+Belgica+antarctica.&rft.issn=&rft.date=2012&rft.volume=&rft.issue=&rft.spage=&rft.epage=&rft.artnum=&rft.au=Teets+NM%2C+Kawarasaki+Y%2C+Lee+RE+Jr%2C+Denlinger+DL.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CSystems+Biology%2C+Molecular+Biology%2C+Evolutionary+Biology%2C+Cell+Biology%2C+Biochemistry">Teets NM, Kawarasaki Y, Lee RE Jr, Denlinger DL. (2012). Expression of genes involved in energy mobilization and osmoprotectant synthesis during thermal and dehydration stress in the Antarctic midge, Belgica antarctica. <span style="font-style: italic;">J Comp Physiol B</span> DOI: <a href="http://dx.doi.org/10.1007/s00360-012-0707-2" rev="review">10.1007/s00360-012-0707-2</a></span>
<span style="font-family: "cambria"; font-size: 11pt;"> </span><br />
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<span style="font-family: "cambria"; font-size: 11pt;">For more information or classroom activities on biological deserts, life in the Dead Sea, and life on Antarctica, see:</span><br />
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<span style="font-family: "cambria"; font-size: 11pt;">Biological deserts and gyres – </span></div>
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<a href="http://oceanservice.noaa.gov/facts/deadzone.html"><span style="font-size: 11pt;">http://oceanservice.noaa.gov/facts/deadzone.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://news.sciencemag.org/sciencenow/2008/01/25-01.html"><span style="font-size: 11pt;">http://news.sciencemag.org/sciencenow/2008/01/25-01.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.coas.oregonstate.edu/index.cfm?fuseaction=content.display&pageID=589"><span style="font-size: 11pt;">http://www.coas.oregonstate.edu/index.cfm?fuseaction=content.display&pageID=589</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://oceanmotion.org/html/background/wind-driven-surface.htm"><span style="font-size: 11pt;">http://oceanmotion.org/html/background/wind-driven-surface.htm</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://marinedebris.noaa.gov/info/patch.html"><span style="font-size: 11pt;">http://marinedebris.noaa.gov/info/patch.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.wiserearth.org/article/bea19ef898eca1e2c820690bf8d22640"><span style="font-size: 11pt;">http://www.wiserearth.org/article/bea19ef898eca1e2c820690bf8d22640</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.sciencedaily.com/releases/2011/02/110208142041.htm"><span style="font-size: 11pt;">http://www.sciencedaily.com/releases/2011/02/110208142041.htm</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://disc.sci.gsfc.nasa.gov/oceancolor/additional/science-focus/ocean-color/dead_zones.shtml"><span style="font-size: 11pt;">http://disc.sci.gsfc.nasa.gov/oceancolor/additional/science-focus/ocean-color/dead_zones.shtml</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://serc.carleton.edu/microbelife/topics/deadzone/index.html"><span style="font-size: 11pt;">http://serc.carleton.edu/microbelife/topics/deadzone/index.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.msnbc.msn.com/id/4624359/ns/us_news-environment/t/dead-zones-counted-oceans/"><span style="font-size: 11pt;">http://www.msnbc.msn.com/id/4624359/ns/us_news-environment/t/dead-zones-counted-oceans/</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://news.nationalgeographic.com/news/2010/02/100305-baltic-sea-algae-dead-zones-water/"><span style="font-size: 11pt;">http://news.nationalgeographic.com/news/2010/02/100305-baltic-sea-algae-dead-zones-water/</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.livescience.com/15341-dead-zone-gulf-mexico-hypoxia-floodsdead-zone-gulf-mexico-hypoxia-floods.html"><span style="font-size: 11pt;">http://www.livescience.com/15341-dead-zone-gulf-mexico-hypoxia-floodsdead-zone-gulf-mexico-hypoxia-floods.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.ewg.org/reports/deadzone"><span style="font-size: 11pt;">http://www.ewg.org/reports/deadzone</span></a><span style="font-size: 11pt;"></span></div>
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<a href="http://www.physorg.com/news199376811.html"><span style="font-size: 11pt;">http://www.physorg.com/news199376811.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Life around the Dead Sea – </span></div>
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<a href="http://news.nationalgeographic.com/news/2011/09/110928-new-life-dead-sea-bacteria-underwater-craters-science/"><span style="font-size: 11pt;">http://news.nationalgeographic.com/news/2011/09/110928-new-life-dead-sea-bacteria-underwater-craters-science/</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.sciencedaily.com/releases/2011/09/110921120331.htm"><span style="font-size: 11pt;">http://www.sciencedaily.com/releases/2011/09/110921120331.htm</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://adsabs.harvard.edu/abs/1998SPIE.3441...44O"><span style="font-size: 11pt;">http://adsabs.harvard.edu/abs/1998SPIE.3441...44O</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.wysinfo.com/Dead_Sea/dead_sea_flora.htm"><span style="font-size: 11pt;">http://www.wysinfo.com/Dead_Sea/dead_sea_flora.htm</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Life in Antarctica - </span></div>
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<a href="http://library.thinkquest.org/26442/html/life/"><span style="font-size: 11pt;">http://library.thinkquest.org/26442/html/life/</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<a href="http://www.marinebio.net/marinescience/04benthon/AAlife.htm"><span style="font-size: 11pt;">http://www.marinebio.net/marinescience/04benthon/AAlife.htm</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.coolantarctica.com/Antarctica%20fact%20file/antarctica_animal.htm"><span style="font-size: 11pt;">http://www.coolantarctica.com/Antarctica%20fact%20file/antarctica_animal.htm</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://schaechter.asmblog.org/schaechter/2010/01/cr.html"><span style="font-size: 11pt;">http://schaechter.asmblog.org/schaechter/2010/01/cr.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://soundwaves.usgs.gov/2004/04/fieldwork.html"><span style="font-size: 11pt;">http://soundwaves.usgs.gov/2004/04/fieldwork.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.mobio.com/pages/wiw-antarctica.html"><span style="font-size: 11pt;">http://www.mobio.com/pages/wiw-antarctica.html</span></a><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.mcmurdodryvalleys.aq/activities/directory/11-2F12-Science/11-2F12-Biology-and-ecology"><span style="font-size: 11pt;">http://www.mcmurdodryvalleys.aq/activities/directory/11-2F12-Science/11-2F12-Biology-and-ecology</span></a><br />
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Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com0tag:blogger.com,1999:blog-8136765635696545893.post-27411254500089784982016-09-14T06:00:00.000-04:002016-09-14T06:00:03.983-04:00I Am Your Density -- Life On Ice<div class="MsoNormal">
Biology concepts – <u>density of water</u>, <u>latent heat</u>, <u>stratification</u></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Ernest Rutherford showed that atoms were </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">mostly space by shooting alpha particles at </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">a sheet of gold foil. Only a few particles struck </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">something solid, most just passed straight </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">through – because the atom is mostly the </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">absence of matter.</span></div>
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It is amazing to know that atoms are mostly empty space. Atoms make up everything around us, including the stuff that hurts when it hits me in the head, but even those things are mostly empty space... or maybe its my head that's empty. </div>
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When atoms fit together to form molecules and molecules fit together to form solids and liquids there is also space. How massive the molecules are and how much space is between them determines a substance’s density. </div>
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<b>Density</b> (mass per unit volume) has a big impact on biology, and we have been talking about water for a few weeks, so let’s talk about the density of water. Simply put, without water’s unique density properties, life as we know it on Earth would not be possible.</div>
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Pure liquid water has a density of 1 g/<style>
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</style><span style="font-size: x-small;"><span style="font-family: "cambria";">cm<sup>3</sup></span></span> (or 1 g/ml). This is 800x times the density of air, so moving around in water is much harder and requires more energy than moving around on a land. Try running in the pool – we just aren’t built for moving in water. </div>
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<span style="font-family: "cambria"; font-size: 11pt;">Gram for gram, fish have more muscle than </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">any other vertebrate animal. Notice how the </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">muscle fibers are arranged in different </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">directions to provide forward movement as </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">the skeleton changes orientation.</span></div>
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But fish have adapted streamlined shapes and big muscles in order to move through water a little easier. The skeleton of a fish is the most complex of all vertebrates. The skull anchors the waving of the vertebral column and the attached muscles. The muscle fibers (myomeres) are arranged so that the muscles can contract in several different directions as the swaying motion passes down the fish body. In all, a fish is about 80% muscle. If you are a marine fish, you’d better be even stronger, since ocean water is slightly more dense (between 1.02 and 1.03 g/cm<sup>3</sup>, depending on the salinity). </div>
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But here is the amazing part - when water freezes, its density goes <b>down</b>. Most substances are denser as solids than as liquids, but water is the exception. As ice crystals form, the water molecules arrange themselves in a very particular order, and this order places slightly more space between them as compared to when they are in liquid form. More space means less mass per unit volume, ie. lower density (0.92 g/ml)….. and this is a key to life on Earth.</div>
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<span style="font-family: "cambria"; font-size: 11pt;">Water will form ice crystals in a definite structure, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">with more space between the molecules than when </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">in liquid form. Snow crystals form from water vapor, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">not liquid water, and retain a more hexagonal lattice </span></div>
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Imagine for a moment that ice was denser than water. Then as the winter came, the winds would blow, the surface water in the pond behind your house would start to cool down, but the deeper water would be a little warmer (remember that water has a high specific heat, it likes to retain its heat. As the surface water arranged itself into a crystal form, ie. turned to ice, it would sink. The warmer water would then be pushed up higher and exposed to the colder temperatures, freeze, and fall to the bottom. Eventually the pond would fill with ice, and be completely frozen. </div>
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Few animals or plants could survive in a solid block of ice, so life would cease to exist in the pond. What is more, when spring came, the sun’s energy and warmer temperatures would have to penetrate to bottom of the pond in order to melt all the ice, and this would take longer than a spring summer and fall to occur. Most bodies of water would stay somewhat frozen all year long.</div>
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Our food webs (who eats who) depend so much on the growth in water, and half of the Earth’s oxygen’s production oxygen depends so much on phytoplankton, the one celled plants that float on the water’s surface and release oxygen as a by product of photosynthesis. So we couldn't survive for long with completely frozen bodies of water. What is more, frozen lakes and bays would eliminate huge heat sinks that normally keep the surface of the earth warm, so we would plunge into another ice age.</div>
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Can you imagine if the massive number of aquatic organisms died as a result of their environment being frozen year round? The animals that feed on them would then die, and the animals that feed on them would die, etc. Eventually the animals on the land that feed on the amphibians and fish would die, and so on. What’s more, we humans would be looking for more warm clothing while we gasped for enough oxygen to survive! Relax, we are all just fine, and it is because ice floats. Surface water freezes, trapping heat below and keeping the aquatic organisms comfy and cozy until spring.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJ-SmWWZzfA8wpIrM0bkDGIoap-EIO8XYDu-X8l9OnF4YteOdbsA5caJbzsO8n3L2ouX_dfBdmOHxE4uzYD1Sg71OwNzMqV66sKgbc6Ji8aEuEzUXjP6HA2h2qao98ENWeg320bWc_fJ30/s1600/frozenwoodfrog2.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJ-SmWWZzfA8wpIrM0bkDGIoap-EIO8XYDu-X8l9OnF4YteOdbsA5caJbzsO8n3L2ouX_dfBdmOHxE4uzYD1Sg71OwNzMqV66sKgbc6Ji8aEuEzUXjP6HA2h2qao98ENWeg320bWc_fJ30/s320/frozenwoodfrog2.png" width="320" /></a></td></tr>
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<span style="font-family: "cambria"; font-size: 11pt;">The North American wood frog can freeze </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">solid in a long Arctic winter, but once it thaws, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">it has work to do. It must find a find a mate and </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">then fertilize the eggs. The fertilized eggs have </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">to develop from to tadpoles and then to adults </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">during the short warm period. Then they can </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">freeze next winter.</span></div>
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You might have noticed that above I mentioned that MOST organisms can’t survive being frozen, but there is an exception. The wood frog (<i>Rana sylvatica</i>) winters in shallow burrows that are not protected from the cold. To survive, the frog actually freezes solid!</div>
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Nucleating proteins in the frog’s blood act as point for ice to form as soon as the frost touches the amphibian’s porous skin. Since the frog is still above 0˚C at this point, the freezing is slower, and the frog can control it. As the liquids freeze, the water is pulled out of the frog’s cells.<br />
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It replaces the water with huge amounts of glucose and sugar alcohols, that keep the cells from forming ice crystals (they are sharp and would puncture the cells causing permanent damage and death). Eventually, the frog is 65% frozen and the internal organs are surrounded by a pool of ice until spring, when it takes about 10 hours for the frog to thaw and hop away. Scientists are now using this process to freeze and thaw rat hearts and livers without damage, in hopes to use to the process in human organs for transplant.<br />
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But freezing and thawing a whole organism is harder than using a glucose bath to freeze individual organs. <a href="http://jeb.biologists.org/content/216/2/292.abstract">Research from early 2013</a> shows the energy that <i>R. sylvatica</i> must spend to accomplish this feat. In response to cooling near the freezing point, the wood frog increases its metabolism to prepare for freezing. But this increase in metabolism is nothing compared to the increase the frog undergoes when freezing is first detected in its tissues. Carbon dioxide (a sign of metabolism) is increased by 5.8 fold during freezing, as to the period just before freezing. This increase is needed to mobilize glucose into the tissues as the cryoprotectant.<br />
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The same thing happens when <i>R. sylvatica</i> thaws, metabolism increases to exactly the same degree as during freezing. But in this instance, the increased cellular activity is necessary for re-establishment of homeostasis and for tissue repair (no anti-freezing strategy is perfect). We have a long way to go to mimic the wood frog's entire preservation strategy, especially since the frog may go through these increases as many as twenty times each winter!</div>
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The wood frog takes advantage of freezing in order to survive. Humans can also take advantage of freezing water (other than keeping your drink cold); in fact, your orange juice may depend on it. Freezing of oranges or grapes ruins them for the same reason it kills animals, it causes frostbite. Ice crystals stab through the cell membrane and cell contents spill out. This isn’t conducive to continued function. </div>
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To prevent oranges and grapes from freezing, farmers will spray them with water when their frost warning systems sound the alarm. Does that make sense, spraying with water to keep something from freezing? It has to do with a property of freezing called <b>latent heat</b>. This is an amount of energy taken up or given off when a substance changes phase (solid<span style="font-family: "symbol";"> to </span>liquid<span style="font-family: "symbol";"> to </span>gas). The energy goes to changing the arrangement of molecules with no change in temperature.<span style="font-size: 11pt;"> </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Oranges can be protected from freezing by </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">spraying them with water which then freezes! </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">In a controversial use of genetic modification, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">bacteria that do not permit ice crystal formation </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">can be sprayed on the oranges to compete with </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">the normal bacteria there. These "ice-minus" </span></div>
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<i><span style="font-family: "cambria"; font-size: 11pt;">Pseudomonas syringae</span></i><span style="font-family: "cambria"; font-size: 11pt;"> can reduce frost damage </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">on oranges, but have not been used commercially.</span></div>
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As water surrounding the orange or grape changes from liquid to solid, the formation of crystals gives off heat (539.4 gram-calories per gram of water frozen).<span style="font-size: 11pt;"> </span> The latent heat of the freezing mist is enough to keep the fruit above 0˚C. This technique doesn’t work if the temperature falls much below 0˚C or stays at 0˚C for an extended time, but it does work well enough to save millions of dollars per year in freezing damage.</div>
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Thermal changes have more to do with differences in water density than salt concentration does, so seasonal changes can alter density in both freshwater and salt water. Even if the changes are not enough to form ice or boil the water, differences in temperature can result in different layers of water within a freshwater body or an ocean. </div>
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Both salt water and freshwater are affected by the sunlight that strikes their surfaces. As water warms, it’s density decreases, and the nutrients in the water stay close to the surface. This supplies phytoplankton and algae with lots of food, and blooms can occur.</div>
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As winter approaches, the surface water cools and becomes more dense (down to 4˚C). The dense water drops to the bottom and taking nutrients down to the benthic organisms. When all the water reaches 4˚C, the surface can begin to freeze. </div>
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In the spring, the process is reversed, and the temperature layers (<b>stratification</b>) can churn again. In salt water, the differences in salinity are added to the differences in density to bring complex stratifications, both in salt content and temperature.</div>
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<span style="font-family: "cambria"; font-size: 11pt;">Stratification shows how temperature can set up </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">layers of water of different density (least dense is </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">the epilimnion). In the winter, the water is churned,</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">and then churned again in spring. These churnings </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">based on changing density move the nutrients around </span></div>
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Different organisms thrive in different temperature and salinity layers. In order to stay put, some floating organisms (planktonic) and swimming organisms (nektonic) can adjust their buoyancies. Fish can use swim bladders, which are air filled cavities to help them stay buoyant. The size of the bladder is regulated by the CO<sub>2</sub> and O<sub>2</sub> in the blood that can remain dissolved or leave the blood as a gas.</div>
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Bladderwort plants also use air filled cavities to keep part of themselves afloat. Sharks, on the other hand, produce large amounts of oil in their livers to reduce their density; oil is less dense than water, just look at your salad dressing layers.</div>
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Plankton can also slightly adjust their densities, but floating is easier for very small things. To them, water is thick, the polar charges have a larger effect on their small bodies. It would be like us trying to swim in molasses. They still have to adapt to seasonal changes in density, but they do it in more subtle (and harder to explain) ways.</div>
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Just because there is water around, it doesn’t mean that life will be easy. Next week we will look at a continent-sized exception to idea of water availability.<br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Experimental+Biology&rft_id=info%3Adoi%2F10.1242%2Fjeb.076331&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Real-time+measurement+of+metabolic+rate+during+freezing+and+thawing+of+the+wood+frog%2C+Rana+sylvatica%3A+implications+for+overwinter+energy+use&rft.issn=0022-0949&rft.date=2012&rft.volume=216&rft.issue=2&rft.spage=292&rft.epage=302&rft.artnum=http%3A%2F%2Fjeb.biologists.org%2Fcgi%2Fdoi%2F10.1242%2Fjeb.076331&rft.au=Sinclair%2C+B.&rft.au=Stinziano%2C+J.&rft.au=Williams%2C+C.&rft.au=MacMillan%2C+H.&rft.au=Marshall%2C+K.&rft.au=Storey%2C+K.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CAnatomy%2C+Biochemistry%2C+Cell+Biology%2C+Zoology">Sinclair, B., Stinziano, J., Williams, C., MacMillan, H., Marshall, K., & Storey, K. (2012). Real-time measurement of metabolic rate during freezing and thawing of the wood frog, Rana sylvatica: implications for overwinter energy use <span style="font-style: italic;">Journal of Experimental Biology, 216</span> (2), 292-302 DOI: <a href="http://dx.doi.org/10.1242/jeb.076331" rev="review">10.1242/jeb.076331</a></span>
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<span style="font-size: 11pt;">For more information, classroom activities and laboratories on the density of water, latent heat, North American wood frog, or stratification, see:</span></div>
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<span style="font-size: 11pt;">Density of water – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.elmhurst.edu/~chm/vchembook/122Adensityice.html">http://www.elmhurst.edu/~chm/vchembook/122Adensityice.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://aquarius.nasa.gov/seawater_mix_sink.html">http://aquarius.nasa.gov/seawater_mix_sink.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.cleanet.org/clean/community/activities/oceans.html">http://www.cleanet.org/clean/community/activities/oceans.html</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.uas.alaska.edu/attac/ampdf/activity3.pdf//"><span style="font-style: normal;">www.uas.alaska.edu/attac/ampdf/</span><b><span style="font-style: normal;">activity</span></b><span style="font-style: normal;">3.pdf\</span></a></span></cite></div>
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<span style="font-size: 11pt;">latent heat – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.splung.com/content/sid/6/page/latentheat">http://www.splung.com/content/sid/6/page/latentheat</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.ucblueash.edu/koehler/biophys/8c.html">http://www.ucblueash.edu/koehler/biophys/8c.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.3dplumbing.net/ontplumbing/latent_heat.htm">http://www.3dplumbing.net/ontplumbing/latent_heat.htm</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.cbu.edu/~jholmes/P201/Part42.ppt"><span style="font-style: normal;">www.cbu.edu/~jholmes/P201/Part42.ppt</span></a></span></cite></div>
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<span style="font-size: 11pt;"><a href="http://apollo.lsc.vsc.edu/classes/met130/notes/chapter2/lat_heat2.html">http://apollo.lsc.vsc.edu/classes/met130/notes/chapter2/lat_heat2.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.hk-phy.org/contextual/heat/cha/act_boiler_lf_e.html">http://www.hk-phy.org/contextual/heat/cha/act_boiler_lf_e.html</a></span></div>
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<span style="font-size: 11pt;">North American wood frog – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.fcps.edu/islandcreekes/ecology/wood_frog.htm">http://www.fcps.edu/islandcreekes/ecology/wood_frog.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.dnr.state.mn.us/reptiles_amphibians/frogs_toads/truefrogs/wood.html">http://www.dnr.state.mn.us/reptiles_amphibians/frogs_toads/truefrogs/wood.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.units.muohio.edu/CRYOLAB/projects/woodfrogfreezing.htm">http://www.units.muohio.edu/CRYOLAB/projects/woodfrogfreezing.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.naturenorth.com/winter/frozen/frozen3.html">http://www.naturenorth.com/winter/frozen/frozen3.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.pbs.org/wgbh/nova/nature/costanzo-cryobiology.html">http://www.pbs.org/wgbh/nova/nature/costanzo-cryobiology.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://news.nationalgeographic.com/news/2007/02/070220-frog-antifreeze.html">http://news.nationalgeographic.com/news/2007/02/070220-frog-antifreeze.html</a></span></div>
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<span style="font-size: 11pt;">stratification – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.waterontheweb.org/under/lakeecology/05_stratification.html">http://www.waterontheweb.org/under/lakeecology/05_stratification.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.maine.gov/doc/nrimc/mgs/education/lessons/act37.htm">http://www.maine.gov/doc/nrimc/mgs/education/lessons/act37.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.windows2universe.org/php/teacher_resources/activity.php">http://www.windows2universe.org/php/teacher_resources/activity.php</a></span></div>
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<span style="font-size: 11pt;"><a href="http://pubs.acs.org/doi/abs/10.1021/ed081p1312A">http://pubs.acs.org/doi/abs/10.1021/ed081p1312A</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.schoolship.org/files/inlandseas/649.pdf"><span style="font-style: normal;">www.schoolship.org/files/inlandseas/649.pdf</span></a></span></cite></div>
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<span style="font-size: 11pt;"><a href="http://www.ehow.com/how_7374642_create-stratified-water-graduated-cylinder.html">http://www.ehow.com/how_7374642_create-stratified-water-graduated-cylinder.html</a></span></div>
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<span style="font-size: 11pt;"><a href="http://centerforoceansolutions.org/climate/impacts/ocean-warming/water-column-stratafi/">http://centerforoceansolutions.org/climate/impacts/ocean-warming/water-column-stratafi/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://faculty.gvsu.edu/videticp/stratification.htm">http://faculty.gvsu.edu/videticp/stratification.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://eesc.columbia.edu/courses/ees/climate/lectures/o_strat.html">http://eesc.columbia.edu/courses/ees/climate/lectures/o_strat.html</a></span></div>
<span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.lmvp.org/Waterline/spring2002/stratification.htm">http://www.lmvp.org/Waterline/spring2002/stratification.htm</a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1tag:blogger.com,1999:blog-8136765635696545893.post-88512352858520042632016-09-07T06:00:00.001-04:002016-09-07T06:00:00.301-04:00Do You Drink Like A Fish?<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Biology concepts – <u>fish osmoregulation</u>, <u>shark osmoregulation</u>, <u>semelparity</u>, <u>iteroparity</u></span></div>
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<span style="font-size: 11pt;">The irony of fish drinking is not lost on this café in </span></div>
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<span style="font-size: 11pt;">the Hotel Portofino at Universal Orlando. What I </span></div>
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<span style="font-size: 11pt;">really like is the eye patch.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">You’d think that fish would never be thirsty; if he needs a drink, he just opens his mouth. But some fish don’t drink a drop! Wouldn’t that be similar to some birds never breathing? Ridiculous. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Fish are good examples of the problems of maintaining proper water and salt concentrations. Some fish live in freshwater, and some in saltwater. These are opposite sides of the same coin when dealing with <b>osmoregulation</b>. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Freshwater fish live in a <b>hypotonic </b>(low salt) environment. The flesh of the fish contains more salt than does the water. Diffusion and osmosis work to equalize salt concentrations in different compartments. Therefore, water will move from the lake or river into the fish’s tissues in order to balance the salt concentrations by osmosis. Salt will not move out of the tissues, since there are molecular mechanisms that work to keep the inside. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Like the kangaroo rat, freshwater fish don’t drink. They do take in water when they eat and move water across their gills, but they don’t take in water just for the water. Even without drinking specifically, freshwater fish take in way more water than they need. Anywhere freshwater contacts a fish cell, water will move inward; this includes the gills, the mouth and gut, and the skin. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">In a situation like this, kidney-mediated concentration of urine would be counterproductive; why retain water when water is exactly what you have too much of? Therefore, freshwater fish excrete large amounts of urine. Their kidneys have large glomeruli, which move lots of water into the collecting tubules for excretion. </span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEha9pLxRuYB49XTG8_nnN5YhQ-5leUznkNrY9gGBxhj8xXAyb3sVTsYUpM55porcObSQRrujunESUyFlRi-TlSmeOdSd59jE6a7IZCvtck7ouuc5KgiFp-S3imE4TPd1rmKor6GJrsx4ZeU/s1600/fish+and+marine+kidney.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEha9pLxRuYB49XTG8_nnN5YhQ-5leUznkNrY9gGBxhj8xXAyb3sVTsYUpM55porcObSQRrujunESUyFlRi-TlSmeOdSd59jE6a7IZCvtck7ouuc5KgiFp-S3imE4TPd1rmKor6GJrsx4ZeU/s320/fish+and+marine+kidney.jpg" width="276" /></a></td></tr>
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<span style="font-size: 11pt;">Saltwater and freshwater fish have different ways of</span></div>
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<span style="font-size: 11pt;">dealing with salt and water loss and conservation.</span></div>
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<span style="font-size: 11pt;">Freshwater fish must conserve salt, while saltwater </span></div>
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<span style="font-size: 11pt;">fish must conserve water. The kidneys play a role, </span></div>
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<span style="font-size: 11pt;">but so do the chloride cells in the gills.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">But if the freshwater fish aren’t drinking, how do they get their salt, which is present in low concentrations in the water? You’d think they would have to be drinking all the time just to collect enough salt. To get around this, they conserve the salt they ingest through the food they eat. They also take in salts through their gill <b>chloride cells</b>, actively pumping sodium and chloride out of the freshwater and into cells that have a lot of mitochondria (to provide energy to pump the salts). The relatively short collecting tubules of the freshwater fish kidney allow for reuptake of a lot of salt, while excluding almost all the water.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Marine (saltwater) fish have the opposite problem. Their tissues are of much lower salt than they surrounding <b>hypertonic</b> ocean, so osmosis wants to dry them out, sending water out of their bodies. The amount of available drinking water is extremely low - can you imagine dying of dehydration while surrounded by water. Just ask anyone who has survived a shipwreck and prolonged float in the ocean; drinking seawater can be lethal.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">However, marine fish must drink all the time in order to keep enough water in their body. Retaining water would be an essential function of marine fish kidneys. They are all fish, but their kidneys work in exactly opposite ways. Marine kidneys have small or absent glomeruli, so little water is taken out of the blood, but long collecting tubules in order to excrete as much salt as possible. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Drinking a lot of saltwater leaves marine fish with way too much salt; more than their kidneys can get rid of. To aid in salt excretion, they also have <b>chloride cells</b> in their gills. In the opposite fashion of the specialized gill cells of freshwater fish, the chloride cells of saltwater fish actively sequester salts from the blood, and then pump the sodium and chloride out into the seawater.</span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6MRiPBcZdwv05xPJOTpcSAtTA8W6qiU0LZp8ZO2Cc20llfYyP3vJIjg_nL4kWzpvZ1nCWhwXkC295pa6jIBRoj2rX2_KbWT6mL3UxauDgsq4_DD2C6Wyw3kSvFnAkeXXYJjQAMIGvNBVl/s1600/shark-fin-salt-and-pepper-shakers.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6MRiPBcZdwv05xPJOTpcSAtTA8W6qiU0LZp8ZO2Cc20llfYyP3vJIjg_nL4kWzpvZ1nCWhwXkC295pa6jIBRoj2rX2_KbWT6mL3UxauDgsq4_DD2C6Wyw3kSvFnAkeXXYJjQAMIGvNBVl/s200/shark-fin-salt-and-pepper-shakers.jpg" width="200" /></a></td></tr>
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<span style="font-size: 11pt;">Sharks have unique ways of maintaining </span></div>
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<span style="font-size: 11pt;">salt and water. I have no idea of their </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">mechanisms for pepper regulation.</span></div>
</td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">But sharks are an exception among marine fish. They have a different way to combat high salt concentrations. Remember that osmosis means that water moves from areas of low solute (high water concentration) to areas of high solute (lower water concentration). For many marine fish, this would mean a constant loss of body water to the ocean and quick death by dehydration; much like pouring salt on a slug. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">To overcome this movement, sharks produce and retain a huge amount of a chemical called urea; it is one of the soluble wastes that animals normally get rid of. This molecule doesn’t affect the electrical potential that salts create, but increases the solute concentration in the shark’s tissues at levels higher than in the seawater, so water (without the salt) will diffuse into the shark’s body. This is its source of fresh water. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Therefore, sharks are <b>osmoconformers</b>; they maintain an osmotic balance with their environment. If the shark becomes too salty and salt needs to be excreted, it has a salt gland, much like that of birds and reptiles, but the shark’s gland is located in it anus, not near its eyes or nose – that’s a big difference! Taken together, there is no force for movement of water in or out of the shark’s tissues, and the shark remains shark-shaped instead of shriveling or swelling up.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzMY92ux9RI5pay9k46wNFzJikUbE8gss7DtLVMB0Zg-1v6zw0R30srdBugPvZdX_hf14sYRdWyPW-XgfDx4S0xrEf8_cHC-QCAHtVg93QZIEgF8JmuXUMelbkXDDKGVxlfKePgRTR9tqr/s1600/BullSharkCaughtInPotomac.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="217" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzMY92ux9RI5pay9k46wNFzJikUbE8gss7DtLVMB0Zg-1v6zw0R30srdBugPvZdX_hf14sYRdWyPW-XgfDx4S0xrEf8_cHC-QCAHtVg93QZIEgF8JmuXUMelbkXDDKGVxlfKePgRTR9tqr/s320/BullSharkCaughtInPotomac.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 11pt;">Here is a bullshark caught in the Potomac River.</span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">And you thought that sharks in Washington D.C.</span></div>
<span style="font-family: "cambria"; font-size: 11pt;">were just in the federal buildings.</span> </td></tr>
</tbody></table>
<div style="text-align: right;">
</div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">An exception to this rule for sharks is the bull shark; it can live in both saltwater and freshwater. Most sharks put into in freshwater would absorb too much water and die of water toxicity. However, the bull shark’s kidneys can adjust to the salinity of the water within a short period of time. Their kidneys will remove less salt and more urea from their blood and tissues and into their urine. They move from being osmoconformers to <b>osmoregulators</b>.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">A shark that can live in freshwater; this can present a real problem. There have been many bull shark attacks in rivers and estuaries (<a href="http://video.nationalgeographic.com/video/player/animals/fish-animals/sharks-and-rays/shark_bull_upriver.html">video</a>), where people don’t expect to encounter sharks. It is suggested that this behavior and physiology is an adaptation that gives the bull shark a protected nursery for their young, away from predators. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Most fish are <b>stenohaline</b> (Greek, steno = narrow and haline = salt), which means they are restricted to either salt or fresh water and cannot survive in water with a different salt concentration than to that which they are adapted. However, there are exceptions- like the bull shark mentioned just a second ago. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="text-align: left;">
</div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Some salmon species are born in freshwater, then move to saltwater for several years, and then return to freshwater to spawn. Other fish, like some eels, are born in a marine environment, move to freshwater, and then go back out to sea to reproduce. If freshwater and saltwater fish kidneys work opposite of one another, how can there be fish that can do both?</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkdIHLoP3KXkaGV4vnowqD3JmPfEzR0cb30WqKfmT6XKDhfy8Qbu42o4Y6dNH4hnikMEX4aL8t22kUiEJS3UFvfY9QIAHJ2ATlIkWRnaTxAKU5rQELgsBThIVUbaqJ3BubYlqbPHI9uZcG/s1600/bear-salmonbetter.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkdIHLoP3KXkaGV4vnowqD3JmPfEzR0cb30WqKfmT6XKDhfy8Qbu42o4Y6dNH4hnikMEX4aL8t22kUiEJS3UFvfY9QIAHJ2ATlIkWRnaTxAKU5rQELgsBThIVUbaqJ3BubYlqbPHI9uZcG/s320/bear-salmonbetter.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 11pt;">Salmon returning upstream to spawn have many obstacles</span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">to overcome. Their spawning grounds are usually a thousand </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">feet or more above sea level so they must leap up many </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">waterfalls. Oh, there are hungry bears too.</span> </td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Salmon are famous for migrating to and from the sea. Almost all the species are <b>semelparous</b> (in Latin, semel = once and parous = breeding); this means that they return to their freshwater streams to spawn only once, and the trip and the reproduction kills them. The one exception is the Atlantic Salmon (<i>Salmo salar</i>). This species is spawned in, and returns to, the calm streams along the Atlantic coast several times in its life to spawn. This reproductive strategy is call <b>iteroparity</b> (itero = repeated). Iteroparous species lay fewer eggs at a time, the advantage is that survival chance is increased by repeated spawning – one bad year doesn’t destroy a big proportion of the population. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">The migratory species of salmon are osmoregulators, as are most freshwater fish; their physiology demands a certain salinity level, and use energy to produce that level in their tissues. However, they can also adapt to various salinity levels. As such, these salmon as well as bull sharks are known as <b>euryhaline</b> (eu = good, haline = salt). Their physiology changes with the salt concentration. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">While in freshwater the salmon will not drink, and will produce copious amounts of urine to get rid of the excess water it absorbs through osmosis. But when it migrates to the ocean, it drinks all the time, and its kidneys work hard to remove the excess salts. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEii-wJm9MAeqKF0jbyI9gKv1b-R2sApWrKjy7GwnaYt2KAi99c10Utl_U3KqiejzrhYGQFb_NOdM-amUqHpRebA68R6hFzda9jsmIEcgWVLAoN5XonR22_Vv_rWD_jIgeatsK-wDTiUVBob/s1600/chloride+cell.gif" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEii-wJm9MAeqKF0jbyI9gKv1b-R2sApWrKjy7GwnaYt2KAi99c10Utl_U3KqiejzrhYGQFb_NOdM-amUqHpRebA68R6hFzda9jsmIEcgWVLAoN5XonR22_Vv_rWD_jIgeatsK-wDTiUVBob/s320/chloride+cell.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 11pt;">Chloride cells in euryhaline fish can sequester or </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">excrete salt, based on the hormone signals they receive. </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">This helps some fish move from aquatic to marine </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">environments and back again.</span> </td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">But the gills are the key to survival in the both the freshwater and saltwater environments. Energy consuming reactions will transport both Na<sup>+</sup> and Cl<sup>-</sup> against their gradients, so they pump Na<sup>+</sup> and Cl<sup>-</sup> into the fish’s tissues in freshwater and out of the fish’s tissues in saltwater. It is an adaptation of the marine fish’s chloride cells to work in both directions. This switch, as well as the kidney’s change in urine concentration, takes time. Therefore, salmon will spend days or weeks in intermediate zones, or <b>estuaries</b>, before going out to the ocean, and before returning to the rivers. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">These are difficult lifestyle choices for salmon, the trips and the spawning kills them. So what is the advantage? The movement to oceans provides the growing salmon with readily available sources of food, so competition is reduced. The return to where they were spawned is just a good bet; if the stream was good enough to spawn them, then it is still probably a good place to lay eggs. Finally, working so hard to get to the spawning ground just a single time allows for selection of strong individuals, allows for huge numbers of eggs to be laid (the chance that some survive goes up), and the death and decomposition of the adults provides nutrients for the hatched fry (baby salmon). But these are human interpretations, I bet there are other advantages and disadvantages. However, one thing is for sure, the balance sheet for these species comes out in favor of these adaptations – if it did not, nature would adapt further. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijsUnj6iyWzIlYoU1PtQxr_OUHwjPzCcnRBJ-lTNIEWpjqBjB-so43QebihH6FdOf4uIPcM9xJzYyuMKY3wNrpME5Nov_q9yfqh2_jI6fof83N_2Qq6sXS7X2DJRgRA3C6UmYCF57YWeJw/s1600/salmon-spawning+many.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="211" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijsUnj6iyWzIlYoU1PtQxr_OUHwjPzCcnRBJ-lTNIEWpjqBjB-so43QebihH6FdOf4uIPcM9xJzYyuMKY3wNrpME5Nov_q9yfqh2_jI6fof83N_2Qq6sXS7X2DJRgRA3C6UmYCF57YWeJw/s320/salmon-spawning+many.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div class="MsoNormal">
<span style="font-size: 11pt;">The eggs that don’t hatch and the carcasses of the mated </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">Adults create nutrient rich waters for the fry to develop in </span></div>
<div class="MsoNormal">
<span style="font-size: 11pt;">before they head out to sea.</span></div>
</td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">How about one more exception for today? Some individuals in semelparous species of salmon (Chinook, Coho, Pink, Steelhead, etc.) will not die after spawning, and will return again to the ocean. These individuals are often females, and are often smaller than average. These gals reverse their salt and water conservation strategies several times in their lives, making them prize winners for osmoregulatory exceptionality. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Next week, let’s tackle how the properties of hard water affect all life on Earth.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Scientific+reports&rft_id=info%3Apmid%2F26403952&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Osmotic%2Fionic+status+of+body+fluids+in+the+euryhaline+cephalopod+suggest+possible+parallel+evolution+of+osmoregulation.&rft.issn=&rft.date=2015&rft.volume=5&rft.issue=&rft.spage=14469&rft.epage=&rft.artnum=&rft.au=Sakamoto+T&rft.au=Ogawa+S&rft.au=Nishiyama+Y&rft.au=Akada+C&rft.au=Takahashi+H&rft.au=Watanabe+T&rft.au=Minakata+H&rft.au=Sakamoto+H&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CAnatomy%2C+Biochemistry%2C+Cell+Biology%2C+Evolutionary+Biology%2C+Zoology%2C+Physiology%2C+Metabolism">Sakamoto T, Ogawa S, Nishiyama Y, Akada C, Takahashi H, Watanabe T, Minakata H, & Sakamoto H (2015). Osmotic/ionic status of body fluids in the euryhaline cephalopod suggest possible parallel evolution of osmoregulation. <span style="font-style: italic;">Scientific reports, 5</span> PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/26403952" rev="review">26403952</a></span>
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=The+Journal+of+experimental+biology&rft_id=info%3Apmid%2F25750413&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Paracellular+pathway+remodeling+enhances+sodium+secretion+by+teleost+fish+in+hypersaline+environments.&rft.issn=0022-0949&rft.date=2015&rft.volume=218&rft.issue=Pt+8&rft.spage=1259&rft.epage=69&rft.artnum=&rft.au=Cozzi+RR&rft.au=Robertson+GN&rft.au=Spieker+M&rft.au=Claus+LN&rft.au=Zaparilla+GM&rft.au=Garrow+KL&rft.au=Marshall+WS&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CEcology+%2F+Conservation%2CAnatomy%2C+Systems+Biology%2C+Biochemistry%2C+Marine+Biology%2C+Environment%2C+Marine+Ecology%2C+Physiology%2C+Metabolism">Cozzi RR, Robertson GN, Spieker M, Claus LN, Zaparilla GM, Garrow KL, & Marshall WS (2015). Paracellular pathway remodeling enhances sodium secretion by teleost fish in hypersaline environments. <span style="font-style: italic;">The Journal of experimental biology, 218</span> (Pt 8), 1259-69 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/25750413" rev="review">25750413</a></span><br />
<span style="font-family: "cambria";"><br /></span>
<span style="font-family: "cambria";"><br /></span>
<span style="font-family: "cambria";">For more information and classroom activities on osmoregulation in fish and sharks, chloride cells, and reproduction strategies, see:</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";">Osmoregulation in fish – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.angelsplus.com/ArticleOsmosis.htm">http://www.angelsplus.com/ArticleOsmosis.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.ca.uky.edu/wkrec/RedDrumPhysiology.htm">http://www.ca.uky.edu/wkrec/RedDrumPhysiology.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.raingarden.us/osmoregulation.htm">http://www.raingarden.us/osmoregulation.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.drjohnson.com/expanded/water/osmoregulation.html">http://www.drjohnson.com/expanded/water/osmoregulation.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.marietta.edu/~mcshaffd/aquatic/sextant/excrete.htm">http://www.marietta.edu/~mcshaffd/aquatic/sextant/excrete.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://marinediscovery.arizona.edu/lessonsS01/blennies/2.html">http://marinediscovery.arizona.edu/lessonsS01/blennies/2.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "cambria";"><a href="http://www.omsi.edu/sites/all/FTP/Files/.../NH.../NH-C1-BendCarrot.pdf"><span style="font-style: normal;">www.omsi.edu/sites/all/FTP/Files/.../NH.../NH-C1-BendCarrot.pdf</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";">Chloride cells – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.bio.umass.edu/biology/mccormick/Cl_cell.html">http://www.bio.umass.edu/biology/mccormick/Cl_cell.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.fishmartinc.com/hc-osmoregulation.htm">http://www.fishmartinc.com/hc-osmoregulation.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "cambria";"><a href="http://www.cnr.uidaho.edu/fish511/Readings/Gill%20morphology.pdf"><span style="font-style: normal;">www.cnr.uidaho.edu/</span><b><span style="font-style: normal;">fish</span></b><span style="font-style: normal;">511/Readings/Gill%20morphology.pdf</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";">Osmoregulation in sharks – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.sharks.org.za/osmoregulation.html">http://www.sharks.org.za/osmoregulation.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.sharksavers.org/en/education/shark-biology-behavior/385-how-bull-sharks-can-live-in-fresh-water-through-clever-osmoregulation.html">http://www.sharksavers.org/en/education/shark-biology-behavior/385-how-bull-sharks-can-live-in-fresh-water-through-clever-osmoregulation.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://meganbioblog.blogspot.com/2010/11/osmoregulation-in-sharks.html">http://meganbioblog.blogspot.com/2010/11/osmoregulation-in-sharks.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.sharksavers.org/en/education/shark-biology-behavior/395-differences-between-sharks-and-bony-fish-more-than-just-the-skeleton.html">http://www.sharksavers.org/en/education/shark-biology-behavior/395-differences-between-sharks-and-bony-fish-more-than-just-the-skeleton.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://users.tamuk.edu/kfjab02/Biology/Vertebrate%20Zoology/b3405_ch04.htm">http://users.tamuk.edu/kfjab02/Biology/Vertebrate%20Zoology/b3405_ch04.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";">semelparity and iteroparity – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://www.nature.com/scitable/knowledge/library/semelparity-and-iteroparity-13260334">http://www.nature.com/scitable/knowledge/library/semelparity-and-iteroparity-13260334</a></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "cambria";"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&ved=0CE4QFjAEOAo&url=http%3A%2F%2Fib.berkeley.edu%2Flabs%2Fslatkin%2Feriq%2Fclasses%2Fbiol472%2Flectnotes%2Flect7_15.pdf&ei=yRMsT7zxB8GQsALxhPitDg&usg=AFQjCNG8SK-33EBWcuipxsTSnty9JEP9hw"><span style="font-style: normal;">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&ved=0CE4QFjAEOAo&url=http%3A%2F%2Fib.berkeley.edu%2Flabs%2Fslatkin%2Feriq%2Fclasses%2Fbiol472%2Flectnotes%2Flect7_15.pdf&ei=yRMsT7zxB8GQsALxhPitDg&usg=AFQjCNG8SK-33EBWcuipxsTSnty9JEP9hw</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";"><a href="http://dictionary.sensagent.com/semelparity+and+iteroparity/en-en/">http://dictionary.sensagent.com/semelparity+and+iteroparity/en-en/</a></span></div>
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<cite><span style="font-family: "cambria"; font-size: 10pt;"><a href="http://www.csun.edu/~msteele/classes/Ich530/lectures/14_reproduction.pdf"><span style="font-style: normal;">www.csun.edu/~msteele/classes/Ich530/lectures/14_reproduction.pdf</span></a></span></cite><span class="vshid"><span style="font-size: 10pt;"></span></span></div>
<span style="font-family: "cambria"; font-size: 10pt;"><a href="http://web2.uwindsor.ca/courses/biology/weis/55-324/lecture9.htm">http://web2.uwindsor.ca/courses/biology/weis/55-324/lecture9.htm</a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com91tag:blogger.com,1999:blog-8136765635696545893.post-55776399100339020262016-08-31T06:00:00.000-04:002016-08-31T17:43:42.757-04:00Don’t Eat The Yellow Snow<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Biology concepts – <u>osmoregulation</u>, <u>tonicity</u>, <u>phytohormones</u>, <u>avian kidney</u>, <u>pinnieds</u>, <u>cetaceans</u></span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">African elephants are larger than asian elephants, but their </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">urine production is similar. A 2007 study found that </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">African elephants can differentiate family members</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">based on their urine. It is similar to marking territory, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">but they use urine to keep track of family members who </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The asian elephant can urinate as much as 55 liters/day. That's about 3/4 of the volume of the average size bathtub! By comparison, the vaunted racehorse can only manage about 6 liters/day. Maybe we should rethink that old saying. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">We know from the posts of the last few weeks that both salts and water are necessary for life, and that they work together to keep their concentrations within safe limits; a process called <b>osmoregulation</b>. You suspect correctly that kidneys and urination is involved, but what about plants – they don’t use the restroom.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">For many animals, the kidney is the major organ of osmoregulation. The average adult human voids 1-2 liters of urine each day, but an uncontrolled diabetic with polyuria (poly=much and uria=urine) might expel 5-6 liters. Maybe we should bet on diabetics at the racetrack.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">We get rid of water and soluble wastes via our kidneys. The kidneys filter the blood; nearly 800 liters of the red stuff each day. The basic filtering unit of the kidney is the nephron, who we met previously (<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><a href="http://biologicalexceptions.blogspot.com/2016/08/sorry-i-dont-drink.html" target="_blank">Sorry, I Don’t Drink</a><span id="goog_1347061558"></span><span id="goog_1347061559"></span><a href="https://www.blogger.com/"></a></span><span id="goog_1347061549"></span><span id="goog_1347061550"></span><a href="https://www.blogger.com/"></a>), made up of the Bowman’s capsule and sets of tubules. </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Solutions of different tonicity have similar effects on plant </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">and animal cells, but plant cells can handle it better because </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">they have a rigid cell wall.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">If the body is low on water, more water is reabsorbed in the tubules. Likewise, if the body has too much salt, few of the salt ions are reabsorbed in the tubules. In this way, our kidneys are basically concentrating our wastes in a small amount of water for excretion from the body. The amount of water depends on many factors, including the need to keep the cells at the right level of <b>tonicity</b> (concentration of salt relative to outside the cells). </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Solutions can be <b>hypertonic</b>, meaning they have more salt than the cytoplasm, and water will flow out of cells by osmosis. Solutions can also be <b>hypotonic</b>, with less salt than in the cells (water will flow in to the cells) or <b>isotonic</b>, with the same osmotic pressure inside the cells as outside.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">We all know that we don’t urinate the same amount all the time – drink more, go more. However, you don’t urinate the same amount you drink; your urine is concentrated by your kidneys in order to conserve water. Therefore, there must be some control mechanism. The answer is hormones. A <b>hormone </b>(“to set in motion” in Greek) is a small protein that is released from one cell and then acts as a chemical signal on other cells, either through the bloodstream (<b>endocrine</b> hormones) or through a duct (<b>exocrine</b> hormones) to the bloodstream or directly to other cells.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">The angiotensin system. 1.</span><span style="font-family: "cambria"; font-size: 12pt;"> </span><span style="font-family: "cambria"; font-size: 11pt;">The body senses that water </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">is low. 2. The kidney releases renin. 3. Renin and </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">angiotensin converting enzyme produce angiotensin II </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">from angiotensin I in the lung. 4. Angiotensin II stimulates </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">aldosterone in the adrenal glands. 5. Aldosterone causes </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">more water and salt to be reabsorbed in the Loop of Henle; </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">this increases the blood volume and solves the problem.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Aldosterone is produced by the adrenal glands and acts on the distal collecting tubules of the kidneys. This endocrine hormone acts to conserve sodium and water and secrete postassium, thereby reducing urine volume but increasing the loss of potassium. Aldosterone is released in response to angiotensin levels in the plasma, which in turn are controlled by sodium and water levels in the blood.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Arginine vasopressin (AVP, also called antidiuretic hormone) is another endocrine hormone that reduces the amount of water to be lost in the urine. This hormone is produced in the pituitary gland of the brain and also works to conserve water. By reducing the amount of water lost, the blood volume (which is mostly water) is increased, so blood pressure increases. This is why people are given intravenous fluids when they have lost a lot of blood.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The exceptions to this mechanism of kidney function are the mammals that live in hypertonic (saltwater) environments, like whales and dolphins (cetaceans) and seals or walruses (pinnipeds, latin for feather- or fin-footed). It is hard to study the urination in these animals in their native environment; they urinate in the ocean. Are you going to measure their individual contribution to the ocean – I think not. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Water wants to flow out of the cells and into the sea (hypertonic as compared to the cells), trying to balance the salt concentrations in both places. Therefore, the marine mammals must conserve freshwater or they become dehydrated. Both pinnipeds and cetaceans have large kidneys with enough renal tubule length to produce very concentrated urine, thereby conserving water. However, it appears cetaceans don’t really take advantage of this. Instead, they make a lot of metabolic water (<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><a href="http://biologicalexceptions.blogspot.com/2016/08/gimme-some-dihydrogen-monoxide.html" target="_blank">Gimme Some Dihydromonoxide</a></span>) and can keep from dehydrating by using the water they produce through cellular respiration. </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Here is an inside view of a seal kidney. It’s huge! The many </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">lobules provides much tubular area to take up freshwater </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Pinnipeds don’t drink water saltwater to any degree at all, they get their freshwater from their diet and their metabolic water. Scientists use to think this was also true for cetaceans, but recent studies show that they do drink a small bit of seawater – not enough meet their water needs, but also not more than their kidney’s can handle.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Don’t think that marine (saltwater) mammals have it so bad. If they were to abandon the seas for freshwater sources, they would just trade one problem for another. Freshwater mammals have too much of a good thing, they run the risk of losing too much salt by being in so much salt poor (hypotonic) water all the time. This is why the kidney is so amazing, it can adapt functionally and anatomically to get rid of too much water or too much salt, depending on where you are. That is not to say the kidney is the only anatomic mechanism needed to maintain osmolarity within a tight range. Many organisms need more than kidneys, and have developed completely different mechanisms of osmoregulation.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Bird kidneys may be small, but they represent an evolutionary </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">intermediate, Some parts have short loops, like most mammals, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">and some have long loops, like pinnipeds and cetaceans. However, </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">most of the kidney has reptile-like nephrons with long loops.</span> </td></tr>
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<span style="font-family: "cambria"; font-size: 12pt;">Birds share some water conserving and salt regulating apparatus with mammals. Avian (bird) kidneys have about 75% of their nephrons with reptilian structure, and 25% mammalian nephrons, containing a Loop of Henle. Therefore, avian kidneys are not as good at removing water and regulating salts as mammals are. Mammal urine can be concentrated 20-50x as compared to blood (the Kangaroo rat can produce a 9000x concentration), but birds can only manifest about a 2-3 fold concentration. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Therefore, birds have another mechanism to get rid of salt and maintain an osmotic potential within its limits. The <b>salt gland</b> is found in birds and reptiles. In many birds it is located near the eyes or nostrils (in crocodiles, salt is excreted through their tongues – everything tastes salty to them). The salt gland removes Na<sup>+</sup> and K<sup>+</sup> from the blood, allowing birds and reptiles to consume saltwater or animals that live in saltwater. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Some organisms have it easier, like amphibians. With semi-permeable skin, they just leak salt out through their entire skin surface. Other organisms aren’t so lucky, like plants.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Plants must also regulate salt concentration, but they don’t have a familiar excretory system; in fact, they don’t have a specific osmoregulatory system. Water is lost via transpiration (<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><a href="http://biologicalexceptions.blogspot.com/2016/08/sorry-i-dont-drink.html" target="_blank">Sorry, I Don’t Drink</a></span>), and adjustments can be made to alter the amount of evaporation that occurs. Unfortunately, transpiration of water is linked to moving nutrients such as salts up the plant from the roots to the leaves. Therefore, shutting down transpiration will also shut down movement of nutrients. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Plants in high temperature, low humidity, high wind environments have the highest rates of transpiration and are in danger of losing too much water. Once again, hormones are the answer. Plants do have hormones (<b>phytohormones</b>), so they probably have to deal with teenager issues just like human parents. Abscisic acid is an important hormone which shuts off transpiration. This phytohormone closes the <b>stomata </b>(stoma = mouth in Greek) on the upper sides of leaves, from which water evaporates and gases are exchanged. Abscisic acid also promotes water absorption from roots and root growth.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">Some plants are cryptophytes by surviving unfavorable </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">seasons either underground (geophytes), hide their </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">seeds in the marshy mud (helophytes) or underwater </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">(hydrophytes). Hydrophytes in general are plants that </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">have their roots in water or water-logged soil.</span> </td></tr>
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<span style="font-family: "cambria"; font-size: 12pt;">Many <b>xerophytes</b> (plants that live in hot, dry places) have adapted to resolve these issues. They have leaf modifications to reduce water loss; needle-shaped leaves, sunken stomata, and waxy cuticles to cover the leaves. On the other hand, in <b>hydrophytes</b> (plants that live completely or almost completely in water), salts and water can be absorbed in the entire plant, not just the roots.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">In terms of cations (Na<sup>+</sup>, K<sup>+</sup>), plants have a problem. They use potassium as their primary intracellular cation, but dirt is usually potassium-poor. Therefore, plants have K<sup>+</sup> transporters to actively take up this ion. Unfortunately, the transporters don’t discriminate very well between K<sup>+</sup> and Na<sup>+</sup>, so often times too much Na<sup>+</sup> is taken up into plants. </span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3Swvvt9veidE2VqKKJKtfDdODC2jnU-pTZ_Ueq5yKThJZAg8MqgcOdCxV7rRB9zGi4fBCm5MuEndOze3BTeQFaTg0vcdg-pwBB2Nput37SjOUkm71EGSyaEAuJExy_O75euFigSwtFImd/s1600/Red-mangrove-leaves1.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3Swvvt9veidE2VqKKJKtfDdODC2jnU-pTZ_Ueq5yKThJZAg8MqgcOdCxV7rRB9zGi4fBCm5MuEndOze3BTeQFaTg0vcdg-pwBB2Nput37SjOUkm71EGSyaEAuJExy_O75euFigSwtFImd/s320/Red-mangrove-leaves1.jpg" width="311" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Red mangroves have impermeable roots that help keep </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">out salt, and can also secrete some salt from there leaves, </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">but their most visible mechanism is the yellow salt leaves.</span> </td></tr>
</tbody></table>
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<br />
<span style="font-family: "cambria"; font-size: 12pt;">Excess Na+ can be toxic to cells, so measures must be taken to deal with these ions. <b>Glycophytes</b> are plants that are salt-sensitive, and include many of the plants that we cultivate. Therefore, soil salinity is an important factor in agriculture and gardening. Much research and breeding continues to an effort to produce crops that are better at differentiating uptake of K<sup>+</sup> and Na<sup>+</sup>. <b>Halophytes</b> (halo=salt, phyte=loving), on the other hand, will allow the uptake of the excess ions, and then sequester them in vacuoles to prevent cellular damage.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<span style="font-family: "cambria"; font-size: 12pt;">Some plants live in extremely high salt environments. One example, the red mangrove tree, is a facultative halophyte. Facultative is a fancy way of saying “optionally.” These trees live in estuaries, where the river meets the sea. The water is quite salty there, and the mangroves are rooted in the water, so excess salt could be a problem. To deal with the toxicity of the excess Na<sup>+</sup>, the mangrove will store the salts in selected leaves, called the “kidney leaves.” When a toxic level is reached, the leaves turn yellow and just drop off. The tree must constantly invest energy in producing new leaves, so there is a cost to this way of life, but it seems to work for them. </span><br />
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<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">If plants that live in or near seawater have adaptive mechanisms to maintain proper salt concentrations, then how about fish? We'll look at the osmoregulatory tricks by these organisms next week.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Plant+science+%3A+an+international+journal+of+experimental+plant+biology&rft_id=info%3Apmid%2F27095399&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Comparison+of+NaCl-induced+programmed+cell+death+in+the+obligate+halophyte+Cakile+maritima+and+the+glycophyte+Arabidospis+thaliana.&rft.issn=0168-9452&rft.date=2016&rft.volume=247&rft.issue=&rft.spage=49&rft.epage=59&rft.artnum=&rft.au=Ben+Hamed-Laouti+I&rft.au=Arbelet-Bonnin+D&rft.au=De+Bont+L&rft.au=Biligui+B&rft.au=Gaki%C3%A8re+B&rft.au=Abdelly+C&rft.au=Ben+Hamed+K&rft.au=Bouteau+F&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CEcology+%2F+Conservation%2CPhysiology%2C+Metabolism%2C+Marine+Ecology%2C+Ecology%2C+Botany%2C+Cell+Biology%2C+Biochemistry%2C+Chemical+Biology">Ben Hamed-Laouti I, Arbelet-Bonnin D, De Bont L, Biligui B, Gakière B, Abdelly C, Ben Hamed K, & Bouteau F (2016). Comparison of NaCl-induced programmed cell death in the obligate halophyte Cakile maritima and the glycophyte Arabidospis thaliana. <span style="font-style: italic;">Plant science : an international journal of experimental plant biology, 247</span>, 49-59 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/27095399" rev="review">27095399</a></span>
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<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Comparative+biochemistry+and+physiology.+Part+A%2C+Molecular+%26+integrative+physiology&rft_id=info%3Apmid%2F23103672&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Osmoregulatory+and+metabolic+costs+of+salt+excretion+in+the+Rufous-collared+sparrow+Zonotrichia+capensis.&rft.issn=1095-6433&rft.date=2013&rft.volume=164&rft.issue=2&rft.spage=314&rft.epage=8&rft.artnum=&rft.au=Pe%C3%B1a-Villalobos+I&rft.au=Vald%C3%A9s-Ferranty+F&rft.au=Sabat+P&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CAnatomy%2C+Behavioral+Biology%2C+Biochemistry%2C+Chemical+Biology%2C+Cell+Biology%2C+Zoology%2C+Physiology%2C+Metabolism">Peña-Villalobos I, Valdés-Ferranty F, & Sabat P (2013). Osmoregulatory and metabolic costs of salt excretion in the Rufous-collared sparrow Zonotrichia capensis. <span style="font-style: italic;">Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, 164</span> (2), 314-8 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/23103672" rev="review">23103672</a></span>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Zoological+science&rft_id=info%3Apmid%2F25660690&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=From+aquatic+to+terrestrial+life%3A+evolution+of+the+mechanisms+for+water+acquisition.&rft.issn=0289-0003&rft.date=2015&rft.volume=32&rft.issue=1&rft.spage=1&rft.epage=7&rft.artnum=&rft.au=Takei+Y&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CAnatomy%2C+Biochemistry%2C+Cell+Biology%2C+Chemical+Biology%2C+Zoology%2C+Evolutionary+Biology%2C+Molecular+Biology">Takei Y (2015). From aquatic to terrestrial life: evolution of the mechanisms for water acquisition. <span style="font-style: italic;">Zoological science, 32</span> (1), 1-7 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/25660690" rev="review">25660690</a></span>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">For more information, classroom activities or laboratories about osmoregulation, tonicity, abscisic acid, avian kidney, pinnipeds, cetaceans, see:</span></div>
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<br /></div>
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<span style="font-size: 11pt;">Osmoregulation – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.biology-online.org/dictionary/Osmoregulation">http://www.biology-online.org/dictionary/Osmoregulation</a></span></div>
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<cite><span style="font-family: "times";"><a href="http://www2.uic.edu/~bcatal1/bios/bios245/learn/osmoregulation.pdf"><span style="font-style: normal;">http://www2.uic.edu/~bcatal1/bios/bios245/learn/</span><b><span style="font-style: normal;">osmoregulation</span></b><span style="font-style: normal;">.pdf</span></a></span></cite></div>
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<span style="font-size: 11pt;"><a href="http://people.eku.edu/ritchisong/bird_excretion.htm">http://people.eku.edu/ritchisong/bird_excretion.htm</a></span></div>
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<span style="font-size: 11pt;"><a href="http://staff.jccc.net/pdecell/cells/paramicium.html">http://staff.jccc.net/pdecell/cells/paramicium.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://5e.plantphys.net/article.php?ch=3&id=268">http://5e.plantphys.net/article.php?ch=3&id=268</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.mhhe.com/biosci/genbio/espv2/data/animals/009/index.html">http://www.mhhe.com/biosci/genbio/espv2/data/animals/009/index.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.zoology.ubc.ca/courses/bio332/Labs/OSMO.HTM">http://www.zoology.ubc.ca/courses/bio332/Labs/OSMO.HTM</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://leavingbio.net/OSMOSIS%20AND%20DIFFUSION.htm">http://leavingbio.net/OSMOSIS%20AND%20DIFFUSION.htm</a></span></div>
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<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">tonicity and osmotic pressure – </span></div>
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<span style="font-size: 11pt;"><a href="http://chemistry.about.com/b/2010/11/09/osmotic-pressure-and-tonicity.htm">http://chemistry.about.com/b/2010/11/09/osmotic-pressure-and-tonicity.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.biotech.ufl.edu/EM/data/osmos.html">http://www.biotech.ufl.edu/EM/data/osmos.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.biologyjunction.com/tonicity%20animations.htm">http://www.biologyjunction.com/tonicity%20animations.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://sciencefair.math.iit.edu/projects/tonicity/">http://sciencefair.math.iit.edu/projects/tonicity/</a></span></div>
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<span style="font-size: 11pt;"><a href="http://www.biology-online.org/biology-forum/about21154.html">http://www.biology-online.org/biology-forum/about21154.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;">abscisic acid – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.plant-hormones.info/abscisicacid.htm">http://www.plant-hormones.info/abscisicacid.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/ABA.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/ABA.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.plantcell.org/site/teachingtools/TTPB12.xhtml">http://www.plantcell.org/site/teachingtools/TTPB12.xhtml</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.pearsonhighered.com/mathews/ch23/abscisic.htm">http://www.pearsonhighered.com/mathews/ch23/abscisic.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/11726706">http://www.ncbi.nlm.nih.gov/pubmed/11726706</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://5e.plantphys.net/article.php?ch=3&id=268">http://5e.plantphys.net/article.php?ch=3&id=268</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://abscissic.blogspot.com/2011/01/abscissic-acid-as-homeostatic-hormonal.html">http://abscissic.blogspot.com/2011/01/abscissic-acid-as-homeostatic-hormonal.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "times";"><a href="http://www.vitis-vea.de/admin/volltext/e034916.pdf"><span style="font-style: normal;">www.vitis-vea.de/admin/volltext/e034916.pdf</span></a></span></cite></div>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">avian kidney – </span></div>
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<span style="font-size: 11pt;"><a href="http://people.eku.edu/ritchisong/bird_excretion.htm">http://people.eku.edu/ritchisong/bird_excretion.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.2ndchance.info/gout.htm">http://www.2ndchance.info/gout.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.ima.umn.edu/biology/wkshp_abstracts/layton1.html">http://www.ima.umn.edu/biology/wkshp_abstracts/layton1.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.holisticbirds.com/pages/urinarysystem0503.htm">http://www.holisticbirds.com/pages/urinarysystem0503.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://en.wikipedia.org/wiki/Salt_gland">http://en.wikipedia.org/wiki/Salt_gland</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">pinnipeds – </span></div>
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<span style="font-size: 11pt;"><a href="http://www.nmfs.noaa.gov/pr/species/mammals/pinnipeds/">http://www.nmfs.noaa.gov/pr/species/mammals/pinnipeds/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/">http://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://marinelife.about.com/od/marinelife101/f/pinniped.htm">http://marinelife.about.com/od/marinelife101/f/pinniped.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
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<span style="font-size: 11pt;"><a href="http://www.sfgate.com/getoutside/pinnipeds.html">http://www.sfgate.com/getoutside/pinnipeds.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "times";"><a href="http://www.farallones.org/documents/pinniped_fs.pdf"><span style="font-style: normal;">www.farallones.org/documents/</span><b><span style="font-style: normal;">pinniped</span></b><span style="font-style: normal;">_fs.pdf</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.cyhaus.com/marine/pinnipeds.htm">http://www.cyhaus.com/marine/pinnipeds.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.whaletimes.org/TenThingsPinnipeds.htm">http://www.whaletimes.org/TenThingsPinnipeds.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://what-when-how.com/marine-mammals/pinniped-physiology-marine-mammals/">http://what-when-how.com/marine-mammals/pinniped-physiology-marine-mammals/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">cetaceans – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.ucmp.berkeley.edu/mammal/cetacea/cetacean.html">http://www.ucmp.berkeley.edu/mammal/cetacea/cetacean.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/">http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.acsonline.org/factpack/index.html">http://www.acsonline.org/factpack/index.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www1.pacific.edu/~e-buhals/cetacean.htm">http://www1.pacific.edu/~e-buhals/cetacean.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.learner.org/jnorth/www/jntalk/0068.html">http://www.learner.org/jnorth/www/jntalk/0068.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<span style="font-family: "cambria"; font-size: 11pt;"><a href="http://what-when-how.com/marine-mammals/osmoregulation-marine-mammals/">http://what-when-how.com/marine-mammals/osmoregulation-marine-mammals/</a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com2tag:blogger.com,1999:blog-8136765635696545893.post-87467237441856587182016-08-24T06:00:00.000-04:002016-08-24T06:00:11.144-04:00Keeping Your “Ion” The Ball – Salts and Life<div style="margin: 0.1pt 0in;">
Biology concepts – <u>salts in biology</u>, <u>osmotic potential,</u> <u>action potential</u>, <u>transpiration</u></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzAi5haMvWcDpU3ZZPl1e-HUU92wXCYGGOB1L-fnJaEfym5pgkhKDtKlI2tTGiWTbBx4KPbbjLnURZthDQwMUz_0-_fkEK1gTb3ae6S87yKDspZNk4Bp34S-FpPKmX87Vo1yx51bNb195G/s1600/veruca_salt1.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzAi5haMvWcDpU3ZZPl1e-HUU92wXCYGGOB1L-fnJaEfym5pgkhKDtKlI2tTGiWTbBx4KPbbjLnURZthDQwMUz_0-_fkEK1gTb3ae6S87yKDspZNk4Bp34S-FpPKmX87Vo1yx51bNb195G/s320/veruca_salt1.jpg" width="313" /></a></td></tr>
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<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: 11pt;">Dietary salt – crucial for survival; </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">Veruca Salt – not so much.</span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">In Latin, verruca means wart, so Roald</span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: 11pt;">Dahl was probably trying to tell us something</span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">when he wrote her character into <i>Charlie</i></span></div>
<i><span style="color: black; font-family: "cambria"; font-size: 11pt;">and the Chocolate Factory</span></i><span style="color: black; font-family: "cambria"; font-size: 11pt;">.</span> </td></tr>
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We have learned that one of the crucial functions of water in living organisms is to help regulate the salt concentration in and between the cells (<a href="http://biologicalexceptions.blogspot.com/2012/01/gimme-some-dihydromonoxide.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Gimme Some Dihydromonoxide</span></a>). But why do living things require salts? We all know that we must have a source of salt (sal in Latin) in our diet or we die; the Romans gave it so much importance that part of a soldiers pay was to be used specifically for buying salt – his <b>sal</b>ary. But what are its functions?</div>
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Water tends to flow from where salts are in low concentration (high water concentration) to where salts are high concentration (low water concentration). Just like other molecules, water <b>diffuses </b>to where its concentration is lower (<a href="http://biologicalexceptions.blogspot.com/2011/08/its-all-in-numbers-sizes-in-nature.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">It’s All In The Numbers-Sizes in Nature</span></a>). <b>Osmosis </b>(osmo = push in Greek) is the special name given to the diffusion of water, for every other molecule it is just called diffusion.</div>
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Too much salt is destructive to cells and organisms, so water helps control the salt held in the body. On the other hand, too much water is also bad for living things (water toxicity), so salts help to control the water concentration. Together, this ratio of salt and water inside and outside of the cell leads to a controlled imbalance called the <b>osmotic potential</b> of the cell. Every living thing has systems to maintain this osmotic potential within a small range (<b>osmoregulation</b>, we will discuss this in more detail soon).</div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS-oXAF-UlBiHyO_8P-_pghpGP2BYuyLQyA9KfYwZLukf1MIoY6lBGm7yQcqVDF6-7XPtIRmqqoyu-D0AgceUeuXB-FvTpHy28PZny8206mSOFtqz0_nI3rsANPjvFI7THnbKAEBnPzXSi/s1600/osmotic+potential.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="143" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS-oXAF-UlBiHyO_8P-_pghpGP2BYuyLQyA9KfYwZLukf1MIoY6lBGm7yQcqVDF6-7XPtIRmqqoyu-D0AgceUeuXB-FvTpHy28PZny8206mSOFtqz0_nI3rsANPjvFI7THnbKAEBnPzXSi/s200/osmotic+potential.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">The osmotic potential is measured in units </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">of pressure (bars). It is equal to the amount </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">of water that will move in response to a </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">difference in solute concentration across </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">a membrane.</span></div>
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When in water, sodium chloride (NaCl, table salt) dissociates into Na<sup>+</sup> and Cl<sup>-</sup> ions, and it is these ions, along with K<sup>+</sup> (potassium ion from KCl) that perform many functions in living organisms. Sodium is 10x more concentrated outside the cell, while potassium is 20x more concentrated inside. The slight difference in the charges of the two ions (and the fact that most Cl<sup>-</sup> is outside cells) sets up a <b>membrane potential</b> in cells. </div>
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An important function of this membrane potential is in the neuron (nerve cell), as rapid reversal of the potential along the cell membrane (through ion specific channels) produces an electrical current that we know as the <b>action potential</b> (neural impulse). It is the rapid change in concentrations of Na<sup>+</sup> and K<sup>+</sup> <b>cations</b> (positively charged ions) inside and outside of the neurons that sends the messages from our muscles to our brains and back, as well as all the thought processes in our brain.</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguH9ts1fLfa5CtqJoDguOuqEIXmNG6kIJos-IAcLqHBhECBIXvMB5G9HL4z8Jhw5zWW993YCXWrFM4djqm_5Vo2kHMZ1T6WFBp1f_hewg64o8LF_EtFUuAdUcue-FxkO9p5WZDCDQpswqz/s1600/action_potential.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguH9ts1fLfa5CtqJoDguOuqEIXmNG6kIJos-IAcLqHBhECBIXvMB5G9HL4z8Jhw5zWW993YCXWrFM4djqm_5Vo2kHMZ1T6WFBp1f_hewg64o8LF_EtFUuAdUcue-FxkO9p5WZDCDQpswqz/s320/action_potential.jpg" width="253" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: 11pt;">The action potential of the neuron is not simple.</span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">Sodium is higher outside and potassium is higher inside.</span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">When a signal is received (usually from another neuron),</span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">sodium leaks in and potassium leaks out. The slight </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">difference in the the charge of each means that the neuron</span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">goes from -70 mV to +40 mV. This depolarization travels</span></div>
<span style="color: black; font-family: "cambria"; font-size: 11pt;">down the neuron’s membrane for the entire cell.</span> </td></tr>
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Salt's importance is illustrated when their concentrations get out of whack. Too little salt produces symptoms similar to dehydration, with cramping, nausea and confusion. Too much salt results in hallucinations and insanity. The classic example of too much salt intake is being lost at sea. Not having a supply of freshwater, people may start to drink seawater. The salt concentration is too high; their kidneys can’t get rid of all the excess, and the action potentials in the brain begin to misfire. People will see things that aren’t there, and will make critically bad decisions. Many end up swimming away from relative safety and subsequently drown.</div>
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We can get rid of some salt through our skin. Is your dog is happy to see you when licking your face after you arrive home, or does he just want the salt? Athletes will often eat bananas to augment their potassium stores and keep the cramps away after exercising. They should really follow that run with a bowl of lima beans; they have much more potassium. </div>
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However, munching on black licorice is alot like running a long distance. Glycyrrhizin is the main glycoside (a sugar bound to a non-carbohydrate) in licorice root and is 20x sweeter than sucrose. Glycyrrhizin prevents potassium reuptake in the kidney, so you end up urinating out most of your potassium stores. You could cramp up due to excessive snacking.<br />
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The source of glycyrrhizin’s effect on potassium reuptake
has to do with cortisol, a stress hormone. Cortisol is converted to cortisone,
but glycyrrhizin inhibits this conversion. The increased cortisol makes it
appear like your body has too many salts in the blood, and you adjust. This isn’t
just a problem for the people who eat a lot of licorice. </div>
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<a href="http://www.sciencedirect.com/science/article/pii/S0306453010001125"><span style="background-color: white;"><span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto;">A 2010 study</span></span></a> indicates that pregnant women who eat licorice can permanently
affect their children’s hormone control in their brains. The
hypothalamic-pituitary-adrenocortical axis (HPAA), is a relay that controls the
child’s production of cortisol, aldosterone and other hormones. These work to
control the osmotic potential of the blood and therefore the blood pressure (as
well as other things).</div>
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The researchers data shows that maternally ingested licorice
inhibits the fetal barrier to maternal cortisol. More cortisol then passes to
the fetal blood system, and programs the HPAA to have a higher baseline. From
then on, the babies make more cortisol, a stress hormone that puts pressure on
the physiology, sodium and potassium levels, and can lead to weight gain. Moms – take care – what you eat
does affect your baby.<br />
<br />
Na<sup>+</sup> and K<sup>+</sup> work in muscle function; cramping and paralysis may result from too little or too much salt. Your heart is a muscle, so changes in salt concentration in the cell can cause heart attacks as well. Many a mystery movie has included the injection of potassium chloride to induce a heart attack. Sodium and potassium cations help maintain proper blood pressure, proper acid/base levels, and proper movement of carbon dioxide from the blood to the lungs. There are precious few functions in which these positive ions don’t play a role. <br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivcyTVoQQ1-qToxQwBni-GhnFt7ogaORJjSpSp1vA1pC1avzbZOjFhUIM2QPt0c4YyltxmQustKR1vGZlmg9TktGKOn_8jMpAB9HtuRXrmmAqs63tpK8vHwz5pvfNR6_ZZLp_70zQQiFty/s1600/collagen+elastin.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="233" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivcyTVoQQ1-qToxQwBni-GhnFt7ogaORJjSpSp1vA1pC1avzbZOjFhUIM2QPt0c4YyltxmQustKR1vGZlmg9TktGKOn_8jMpAB9HtuRXrmmAqs63tpK8vHwz5pvfNR6_ZZLp_70zQQiFty/s320/collagen+elastin.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: 11pt;">Collagen and elastin help to make your skin and </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">joints pliable. O.K., maybe not <b>this</b> elastic – this is </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">the result of Ehlers-Danlos syndrome, which is </span></div>
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<span style="color: black; font-family: "cambria"; font-size: 11pt;">often a genetic disease.</span></div>
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When we think of salt, we usually think of table salt (NaCl), but there are more functions for K<sup>+</sup> than there are for Na<sup>+</sup>, and it is present in higher concentrations in the cell. Potassium is important for the formation and crosslinking of collagen and elastin proteins. These connective tissue proteins hold all your tissues together; they keep your skin from tearing when someone pokes you in the arm, and allow your lungs to expand without ripping when you inhale. So K<sup>+</sup> is pretty important even when not working with Na<sup>+</sup>. It is interesting then that potassium is the only major mineral nutrient for which there is not a recommended daily allowance.</div>
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Remember that we often take in these salts as NaCl or KCl. Does the Cl<sup>-</sup> play a role in organism function? – you bet it does. Chloride <b>anion</b> (a negatively charged ion) is used to produce the hydrochloric acid (HCl) that breaks down the food in our stomachs. Chloride also works in the immune system, <b>hypochlorite</b> (the same active molecule as in bleach) in the white blood cells helps to kill infectious agents and activates other immune system molecules. Chloride is required for the uptake of vitamin B12 and iron and helps control your blood pressure; therefore, Cl<sup>-</sup> isn’t just that other ion that comes in with Na<sup>+</sup> or K<sup>+</sup> (or Ca<sup>2+</sup>).</div>
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Chloride ion is elemental chlorine that has gained one electron. This doesn’t seem like much of a change, but it is the difference between life and death. Chlorine itself is a yellowish green gas and it can kill you in a matter of seconds. Chlorine really wants that extra electron, and it doesn’t care if it has to rip it from your lung proteins to get it. When you breathe in chlorine, it reacts with the water in your lungs to produce hydrochloric acid that eats away the cells. It will also react with almost any carbon-containing molecule and further destroy the lung tissue. It was suggested during the American Civil War that chlorine gas could be useful, but it wasn’t until World War I that it was used as a weapon.</div>
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Chlorine is poisonous, but we use it to disinfect drinking water and pools. When diluted greatly in water, chlorine does not have the strongly deleterious effect on our cells as it does as a gas, but can still react with and kill microorganisms. Chlorination of water began in the Chicago stockyards around 1908, when the decaying meat and gut bacteria were getting into the drinking water and making the residents sick. The bleach used to disinfect surfaces is much the same as the chlorine used to disinfect 75% of the drinking water in the U.S.; it’s just there in lower concentration. Now chlorine is used in pools as well, and you know it is working because your eyes get red and sting. </div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFjpyxuEXhm2vfx8URr6Ck9OSd7F5OBQFmsdWoMl5rFWuKr2FgjJ_k6P2rcqxCbBIig0KsJQsSXtb2CDXZ4V2T96PCUyu8Ziy3OhTFC7I7_y8_3C3vxsMPVukV0mBC5pNMpOB9_4b99qWz/s1600/stomates.gif" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="175" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFjpyxuEXhm2vfx8URr6Ck9OSd7F5OBQFmsdWoMl5rFWuKr2FgjJ_k6P2rcqxCbBIig0KsJQsSXtb2CDXZ4V2T96PCUyu8Ziy3OhTFC7I7_y8_3C3vxsMPVukV0mBC5pNMpOB9_4b99qWz/s320/stomates.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="font-family: "cambria"; font-size: 11pt;">Did you know that plants had openings in their leaves called </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">stomata? <b>Turgor pressure</b> caused by the flow ions in and </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">out of the guard cells makes the stomata open or close. Their </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">shape changes based on the amount of water in the guard cell.</span> </td></tr>
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There are no exceptions to the rules of salt requirements (weird, isn’t it). All living things need to take in Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup>, and even Cl<sup>-</sup>. Plants use potassium and sodium for water balance, especially to bring morphologic changes like the blooming of flowers. These cations, along with chloride, work in the opening and closing of pores in the leaves (<b>stomata</b>) for the uptake of carbon dioxide and the release of oxygen and water during transpiration (<a href="http://biologicalexceptions.blogspot.com/2012/01/gimme-some-dihydromonoxide.html"><span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);">Gimme Some Dihydromonoxide</span></a>), and in the chemical splitting of water during photosynthesis. It seems that other organisms rely on these ions even more than animals.</div>
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All bacteria require potassium and sodium for osmotic regulation and cellular activities. </div>
As the concentration of Na<sup>+</sup> in a bacteria’s environment goes up, its dependence on Cl<sup>-</sup> becomes greater.<span style="font-family: "cambria"; font-size: 12pt;"> Fungi, protists, and even viruses depend on salts to remain alive, even though viruses are technically not a form of life. Viruses carry nucleic acid, and salts are needed to balance the charges of the DNA or RNA so it can be stuffed into the viral package, a function within the area of molecular biology. </span>
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<span style="font-family: "cambria"; font-size: 12pt;"> </span></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxtdIXGrHza9Z2qcF58NrjEceXiHmbGYiHB_dnHsRfLHQnXSJeTykB4Xxbrm6dqIK3eOllv3eo2C-J0R9x96aoy3j4xML0qs_lceGWWCf0kzOacVFjM8o6t3iFczhtHwaj12DiFZYrFo3v/s1600/C0031943-Giardia_Lamblia-SPL.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjxtdIXGrHza9Z2qcF58NrjEceXiHmbGYiHB_dnHsRfLHQnXSJeTykB4Xxbrm6dqIK3eOllv3eo2C-J0R9x96aoy3j4xML0qs_lceGWWCf0kzOacVFjM8o6t3iFczhtHwaj12DiFZYrFo3v/s320/C0031943-Giardia_Lamblia-SPL.jpg" width="255" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<i><span style="font-family: "cambria"; font-size: 11pt;">Giardia lamblia</span></i><span style="font-family: "cambria"; font-size: 11pt;"> and other protozoa use salt ions </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">to control their osmotic potentials and for other </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">biochemical functions. Giardia can also change </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">your potassium levels by causing intense diarrhea </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">after drinking contaminated stream water.</span> </td></tr>
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Molecular biology involves replication of DNA, the transcription of DNA to RNA, and the activities of RNA translation to proteins. K<sup>+</sup>, Cl<sup>-</sup>, and Na<sup>+</sup> are involved in all these areas. In a feedback mechanism, salt ions control the switches that turn on genes that then control the levels of the ions. If one ion is too high, it will turn on the genes that code for proteins which remove that ion from the cell. Isn’t evolution nifty?</div>
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Tightly regulating salt concentration in the cell is important for life, and we have to drink water (kangaroo rats excepted) in order to stay alive. These are the peanut butter and jelly of biology and we will start to see how they work together next time.<br />
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Psychoneuroendocrinology&rft_id=info%3Adoi%2F10.1016%2Fj.psyneuen.2010.04.010&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Maternal+prenatal+licorice+consumption+alters+hypothalamic%E2%80%93pituitary%E2%80%93adrenocortical+axis+function+in+children&rft.issn=03064530&rft.date=2010&rft.volume=35&rft.issue=10&rft.spage=1587&rft.epage=1593&rft.artnum=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0306453010001125&rft.au=R%C3%A4ikk%C3%B6nen%2C+K.&rft.au=Seckl%2C+J.&rft.au=Heinonen%2C+K.&rft.au=Pyh%C3%A4l%C3%A4%2C+R.&rft.au=Feldt%2C+K.&rft.au=Jones%2C+A.&rft.au=Pesonen%2C+A.&rft.au=Phillips%2C+D.&rft.au=Lahti%2C+J.&rft.au=J%C3%A4rvenp%C3%A4%C3%A4%2C+A.&rft.au=Eriksson%2C+J.&rft.au=Matthews%2C+K.&rft.au=Strandberg%2C+T.&rft.au=Kajantie%2C+E.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CCell+Biology%2C+Endocrinology%2C+Pathology%2C+Developmental+Biology">Räikkönen, K., Seckl, J., Heinonen, K., Pyhälä, R., Feldt, K., Jones, A., Pesonen, A., Phillips, D., Lahti, J., Järvenpää, A., Eriksson, J., Matthews, K., Strandberg, T., & Kajantie, E. (2010). Maternal prenatal licorice consumption alters hypothalamic–pituitary–adrenocortical axis function in children <span style="font-style: italic;">Psychoneuroendocrinology, 35</span> (10), 1587-1593 DOI: <a href="http://dx.doi.org/10.1016/j.psyneuen.2010.04.010" rev="review">10.1016/j.psyneuen.2010.04.010</a></span>
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For more information and classroom activities on salts in biology, osmotic potential, action potentials, or chloride ion in biology, see:</div>
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<span style="font-size: x-small;"><br />
</span></div>
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<span style="color: black; font-family: "cambria"; font-size: x-small;">Salts in biology – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.ext.colostate.edu/pubs/foodnut/09355.html">http://www.ext.colostate.edu/pubs/foodnut/09355.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.physiologymodels.info/contractile/NaK_pump.htm">http://www.physiologymodels.info/contractile/NaK_pump.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://muscle.ucsd.edu/musintro/ecc.shtml">http://muscle.ucsd.edu/musintro/ecc.shtml</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.webelements.com/sodium/biology.html">http://www.webelements.com/sodium/biology.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e01140.html">http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e01140.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.youtube.com/watch?v=ntlX5Ve6yj8">http://www.youtube.com/watch?v=ntlX5Ve6yj8</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://en.wikipedia.org/wiki/Sodium_in_biology">http://en.wikipedia.org/wiki/Sodium_in_biology</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://en.wikipedia.org/wiki/Potassium_in_biology">http://en.wikipedia.org/wiki/Potassium_in_biology</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.webelements.com/potassium/biology.html">http://www.webelements.com/potassium/biology.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><br />
</span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: x-small;">Osmotic potential – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://physioweb.uvm.edu/diffusion/pages/OsmPotential.htm">http://physioweb.uvm.edu/diffusion/pages/OsmPotential.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://h2g2.com/dna/h2g2/A686766">http://h2g2.com/dna/h2g2/A686766</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><cite><span style="font-family: "times";"><a href="http://www.mrothery.co.uk/studentswork/.../osmosis%20presentation.ppt"><span style="font-style: normal;">www.mrothery.co.uk/studentswork/.../</span><b><span style="font-style: normal;">osmosis</span></b><span style="font-style: normal;">%20presentation.ppt</span></a></span></cite></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://biology.clemson.edu/bpc/bp/Lab/110/osmosis.htm">http://biology.clemson.edu/bpc/bp/Lab/110/osmosis.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://biology.kenyon.edu/HHMI/Biol113/movemet%20of%20water%20in%20plants.htm">http://biology.kenyon.edu/HHMI/Biol113/movemet%20of%20water%20in%20plants.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://5e.plantphys.net/article.php?ch=3&id=29">http://5e.plantphys.net/article.php?ch=3&id=29</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><br />
</span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: x-small;">Action potential – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://students.cis.uab.edu/nkm188/project_back2.html">http://students.cis.uab.edu/nkm188/project_back2.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://faculty.washington.edu/chudler/ap.html">http://faculty.washington.edu/chudler/ap.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://outreach.mcb.harvard.edu/animations/actionpotential.swf">http://outreach.mcb.harvard.edu/animations/actionpotential.swf</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://bcs.whfreeman.com/thelifewire/content/chp44/4402002.html">http://bcs.whfreeman.com/thelifewire/content/chp44/4402002.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-13/CB13.html">http://www.mun.ca/biology/desmid/brian/BIOL2060/BIOL2060-13/CB13.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.blackwellpublishing.com/matthews/channel.html">http://www.blackwellpublishing.com/matthews/channel.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://teach.genetics.utah.edu/content/">http://teach.genetics.utah.edu/content/</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://faculty.washington.edu/chudler/chmodel.html">http://faculty.washington.edu/chudler/chmodel.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://science.education.nih.gov/supplements/nih2/addiction/guide/lesson3-1.htm">http://science.education.nih.gov/supplements/nih2/addiction/guide/lesson3-1.htm</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.accessexcellence.org/MTC/96PT/Share/conley.php">http://www.accessexcellence.org/MTC/96PT/Share/conley.php</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.ywpw.com/cai/software/hhsimu/">http://www.ywpw.com/cai/software/hhsimu/</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><br />
</span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: x-small;">Chloride in biology - </span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/v03/030731r00.HTM">http://web.squ.edu.om/med-Lib/MED_CD/E_CDs/anesthesia/site/content/v03/030731r00.HTM</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://muscle.ucsd.edu/musintro/ecc.shtml">http://muscle.ucsd.edu/musintro/ecc.shtml</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.comprehensivephysiology.com/WileyCDA/CompPhysArticle/refId-cp080117.html">http://www.comprehensivephysiology.com/WileyCDA/CompPhysArticle/refId-cp080117.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.bio.umass.edu/biology/mccormick/Cl_cell.html">http://www.bio.umass.edu/biology/mccormick/Cl_cell.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.webmd.com/a-to-z-guides/chloride-cl">http://www.webmd.com/a-to-z-guides/chloride-cl</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://ivy_league0.tripod.com/rhyme_of_the_ancient_wanderer/id101.html">http://ivy_league0.tripod.com/rhyme_of_the_ancient_wanderer/id101.html</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://labtestsonline.org/understanding/analytes/chloride/tab/test">http://labtestsonline.org/understanding/analytes/chloride/tab/test</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.livestrong.com/article/277296-sodium-potassium-chloride-in-the-body/">http://www.livestrong.com/article/277296-sodium-potassium-chloride-in-the-body/</a></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><br />
</span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-family: "cambria"; font-size: x-small;">stomata – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://faculty.washington.edu/ktorii/stomata.html">http://faculty.washington.edu/ktorii/stomata.html</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://bioweb.usu.edu/kmott/Complexity_Web_Page/Stomata.htm">http://bioweb.usu.edu/kmott/Complexity_Web_Page/Stomata.htm</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://evolution.berkeley.edu/evolibrary/article/mcelwain_03">http://evolution.berkeley.edu/evolibrary/article/mcelwain_03</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.geocraft.com/WVFossils/stomata.html">http://www.geocraft.com/WVFossils/stomata.html</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.nature.com/scitable/topicpage/plant-vacuoles-and-the-regulation-of-stomatal-14163334">http://www.nature.com/scitable/topicpage/plant-vacuoles-and-the-regulation-of-stomatal-14163334</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.biologycorner.com/worksheets/stomata.html">http://www.biologycorner.com/worksheets/stomata.html</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.biologyjunction.com/leaf_stomata_lab.htm">http://www.biologyjunction.com/leaf_stomata_lab.htm</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://uwstudentweb.uwyo.edu/d/dbrouss1/stomate.htm">http://uwstudentweb.uwyo.edu/d/dbrouss1/stomate.htm</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.biologycorner.com/worksheets/stomata.html">http://www.biologycorner.com/worksheets/stomata.html</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.classtech2000.com/toucan/modules/stomata/stomata.htm">http://www.classtech2000.com/toucan/modules/stomata/stomata.htm</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="color: black; font-size: x-small;"><a href="http://www.accessexcellence.org/AE/AEC/AEF/1994/case_leaf.php">http://www.accessexcellence.org/AE/AEC/AEF/1994/case_leaf.php</a></span><span style="color: black; font-family: "cambria"; font-size: x-small;"></span></div>
<span style="color: black; font-family: "cambria"; font-size: x-small;"><a href="http://www.apsnet.org/edcenter/intropp/topics/Pages/OverviewOfPlantDiseases.aspx">http://www.apsnet.org/edcenter/intropp/topics/Pages/OverviewOfPlantDiseases.aspx</a></span></div>
</div>
Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com6tag:blogger.com,1999:blog-8136765635696545893.post-40275655086241829892016-08-17T06:00:00.000-04:002016-08-17T06:00:03.700-04:00Sorry, I Don’t Drink<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Biology concepts – <u>water conservation</u>, <u>kidney function</u>, <u>metabolic water</u>, <u>adaptation</u>, <u>water uptake</u></span></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIkA8K2l7vwBRPUA_19v60dybhPawodxWH25wKQ9kbkaDZ61iBtrfLzVH28WPTgMw-7DGJLNYV18lnT_UXsavD5UKw2t57tgXfjTtZHNR1GolWSRmNtJ48f7qlCXB801XAkXNKVAhoSFSE/s1600/1-koala.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIkA8K2l7vwBRPUA_19v60dybhPawodxWH25wKQ9kbkaDZ61iBtrfLzVH28WPTgMw-7DGJLNYV18lnT_UXsavD5UKw2t57tgXfjTtZHNR1GolWSRmNtJ48f7qlCXB801XAkXNKVAhoSFSE/s320/1-koala.jpg" width="293" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-size: small;"><span style="font-family: "cambria";">“Koala” in aborigine means “no drink.” The </span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: small;"><span style="font-family: "cambria";">moist eucalyptus leaves are poisonous </span></span><br />
<span style="font-size: small;"><span style="font-family: "cambria";">to most animals, but koalas have a special </span></span><br />
<span style="font-size: small;"><span style="font-family: "cambria";">bacteria that can break down the toxic </span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: small;"><span style="font-family: "cambria";">eucalyptus oil.</span></span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">We all know we need water to survive (see <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><a href="http://biologicalexceptions.blogspot.com/2016/08/gimme-some-dihydrogen-monoxide.html" target="_blank">Gimme Some Dihydrogen Monoxide</a></span>), so why is it that koala bears have decided they don’t need to drink? </span></div>
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<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Koalas eat eucalyptus leaves, as well as mistletoe and a few other leaves. The leaves contain a good amount of water, and the koalas can survive on just this source of moisture. It also helps that they sleep about 18 hours each day, have a very slow metabolism, and feed about 80% of the time they are awake - it is apparent that they have evolved into teenagers. This doesn’t mean that koalas can’t or don’t drink, they just don’t require drinking to get their daily requirement of water unless a drought dries up the leaves. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">However, there exist species that never drink. The kangaroo rat and the spinifex hopping mouse take temperance to the extreme. These rodents can live out their entire life (5-7 years) and never use the water fountain. They have chosen their lifestyles wisely, considering that the hopping mouse lives in the Australian outback and the kangaroo rat lives in Death Valley! We will use the kangaroo rat as our exemplar for this exception.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Unlike the koala that gets its water from its diet, the kangaroo rat eats seeds- not a great source of water. Therefore, it must have other strategies for survival. Foremost, it has developed ways to prevent water loss. Its kidneys super-</span><span style="font-family: "cambria"; font-size: 12pt;">distill its urine so it is up to 17 times more concentrated than its blood; the best we can do is 3-4 times concentration.</span><span style="font-family: "cambria"; font-size: 12pt;"> </span></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWh7A2lgEcurKJBmOJQHtQ3KLsrsoz3ZOlKze6uwz_VUMrnbTpxNOVSeFXD6WEHBJtqf-_Dgj23e0TSgU2_McEMwjRvxJ6MZIfESoMsf0jqAjC_IGWcQFgDK2GHK99Z8SGOvBiovBK_y4z/s1600/2-nephron.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="276" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWh7A2lgEcurKJBmOJQHtQ3KLsrsoz3ZOlKze6uwz_VUMrnbTpxNOVSeFXD6WEHBJtqf-_Dgj23e0TSgU2_McEMwjRvxJ6MZIfESoMsf0jqAjC_IGWcQFgDK2GHK99Z8SGOvBiovBK_y4z/s400/2-nephron.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Please meet the nephron. The blood vessels form a </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">glomerulus, which is surrounded by the Bowman’s capsule. </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Notice how the blood vessels surround the Loop of </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Henle to take the retained water and salts back into </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">the blood.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">The kidney is made up of thousands of filtering units called <b>nephrons</b> (Greek nephros = kidney). Each nephron has a <b>Bowman’s capsule</b> that filters the blood of waste,and removes some of the water and salt. The filtrate then flows through a series of tubules that adjust the concentration of the salts and water according to what the body needs to retain or dispose of at that particular moment. The portion of the kidney that removes water from the urine back to the blood are called the <b>Loop of Henle</b>, and these loops are much longer in the kangaroo rat’s kidney as compared to those in human kidneys. Therefore, more water is returned to the blood and the urine wastes are more concentrated.</span></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_T6soAlrTCWT8RnKeDA3csrhEZ-dqmZ_qJ5If5c9D2I5SN6DxdEdM7mdkXkD08zTngUE_gGJ1PZfQ-oAsRjlgZTj-pwrVJPjwKJ3jfgvMvKmhhnvlnJAmioUaDx8cRo8bniwccYGQwA2O/s1600/3-+kangaroo.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_T6soAlrTCWT8RnKeDA3csrhEZ-dqmZ_qJ5If5c9D2I5SN6DxdEdM7mdkXkD08zTngUE_gGJ1PZfQ-oAsRjlgZTj-pwrVJPjwKJ3jfgvMvKmhhnvlnJAmioUaDx8cRo8bniwccYGQwA2O/s200/3-+kangaroo.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">The kangaroo rat doesn’t look thirsty, </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">even though it doesn’t look like his </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">burrow has seen water for years. </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">I would imagine that despite the hot </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">weather and the fur coat, kangaroo </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">rats don’t sweat; they can’t afford the </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">water loss.</span></div>
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</tbody></table>
<br />
<br />
<br />
<br />
<br />
<span style="font-family: "cambria"; font-size: 12pt;">The kangaroo rat doesn't stop there. He burrows deep and keeps his burrow small. This helps to trap and moisture that escapes via his exhalations. If you breathe on a mirror, it will show condensation; you invest a lot of water in keeping your lungs moist and functional. The rat can reabsorb some of the moisture present in its burrow via its skin, respiratory tract, and his seeds. </span><br />
<br />
<span style="font-family: "cambria"; font-size: 12pt;">The dry seeds that the kangaroo rat finds are stored in a pouch in its mouth and taken back to the burrow. Here they are stored for several days in a corner, during which time they also absorb moisture from the burrow’s air. This is just another way the rat recycles some of its own moisture. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Finally, the kangaroo rat makes the most of the water it produces. Yes, it generates water – but so do you. Think of the production of ATP (aerobic respiration) as the opposite of photosynthesis. In the building of carbohydrates (during photosynthesis). In photosynthesis, water is split and the hydrogen is added to the growing carbohydrate. But in the <b>electron transport chain</b> for <b>oxidative</b> <b>phosphorylation</b> (making ATP) oxygen accepts an electron and then reacts with hydrogen to form water. Water made this way is called <b>metabolic water</b>. In humans, metabolic processes like generation of ATP produce about 2.5 liters of water each day. In the kangaroo rat, this process is more efficient and the water produced is kept in house.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">As the electrons from the breakdown of glucose travel down the </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">electron transport chain in the mitochondrial membrane, they </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">help to move protons (H+) out. As they leak back in through the</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">ATPase, they help make ATP. The electron needs some place to go, </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">and an oxygen atom is a good place to go. This makes </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">the oxygen reactive; it picks up hydrogens to form water.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Add all these measures up and the kangaroo rat changes its habitat from Death Valley to Life Valley. Unfortunately, not many other organisms can join it there. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Just because it doesn't drink or eat watery foods doesn’t necessarily mean that an organism doesn’t take in water. Amphibians absorb environmental (air or surface) water through their skin. Frogs are a group of amphibians that can be used as good examples. Frog skin is smooth, without hair or feathers, and is permeable to water. A <b>ventral patch</b> (sometimes called a seat patch) of skin is located on the underside of the frog between its two hind legs. This skin patch has a higher concentration of blood vessels just beneath the surface, ready to suck available water into the bloodstream. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">To get to the blood vessels below the skin, the water passes through a series of <b>aquaporin</b> (aqua = water, pore = opening) protein channels in the skin cells. These proteins also control water entry into bacteria; they are evolutionarily very old and therefore must be important. The frog splays its legs and lays down on a surface that is moist from dew or rain, and the water flows through the ventral patch aquaporins and into the bloodstream. Interestingly, water doesn’t flow the other direction, although some water does evaporate through amphibian skin. That is why frogs must live close to water. Toad skin is much less likely to lose water, so they can live farther from water.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Some plants also garner water in unconventional ways. <b>Non-vascular plants</b> (mosses, lichens, liverworts, hornworts) as well as many <b>epiphytes</b> (bromeliads, orchids, some ferns and mosses, mistletoe) are plants without roots. However, a lack of roots or vessels doesn’t stop these plants, they have evolved marvelous adaptations to procure the water they must have.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Non vascular plants are just that – plants without vascular tissues (<b>xylem</b> and <b>phloem</b>). Plant vascular tissues are tubes inside the stem that transport water (phloem) and sugars (xylem) throughout the plant. Non-vascular plants don’t have roots and vessels to absorb and transport water and minerals, although mosses and ferns may have rhizoids that serve that purpose. In general, non-vascular plants grow close to water so that they can use all their structures to absorb water by capillary action as well as by absorbing water directly from the air. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Epiphytes are even better at pulling water from the air, although they still use pooled rainwater as well. This group of plants may have dense root systems, but some are not anchored in the ground to give support to the plant. Instead, many of them use other plants for support. Orchids are particularly good at storing water in their thick stems and absorbing water through their exposed roots. <b>Velamen </b>(latin for veil or cover) layer root cells of orchids are adapted to prevent water loss while a few cells in this layer and the layer below are hollow and allow water to pass through.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Bromeliad epiphytes are better at absorbing pooled water and humidity through their leaves than in taking water in through their roots. In tropical regions, they have two adaptations to aid this process. One, many bromeliads have near vertical leaves shaped to trap water at their bases (together called a tank) that may hold over a liter of water. Second, they have specialized cells at the base of the leaves to transfer this water (and minerals) to the interior of the plant. The most economically important of this Bromelioideae subfamily is the pineapple, which is a terrestrial bromeliad. It can absorb water through its roots in the ground, but if you are growing one, try to keep the tank from drying out as well.</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">The top picture is looking down on a bromeliad trichome. </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">The middle picture is looking from the side. See how they </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">curl up to allow water in. When they fill with water, </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">they fold down (lowest picture), to prevent water loss </span><br />
<span style="font-family: "cambria"; font-size: 11pt;">from the cells underneath.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Bromeliads living in areas with less rain, such as Spanish moss, have a different adaptation. Their leaves store the water that is absorbed through specialized structures called <b>trichomes</b> on the surface of each leaf. Trichomes have shields made of non-living cells, much like our outer layers of skin. Other cells form a disc and are mostly a void, capable of rapidly taking in water. When these cells swell, their tips curl downward (remember turgor pressure from <span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><a href="http://biologicalexceptions.blogspot.com/2016/02/plants-that-dont-sleep-will-take-dirt.html" target="_blank">Plants That Don’t Sleep Well</a></span>). </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Curling forms a small cavity under the disc that draws water in to the protected foot cells under the disc by capillary action. These cells also have aquaporin proteins that draw the water into the interior tissues. When there is less water around, the disc cells flatten out and cover the stalk cells, preventing water loss. The whole structure acts like an anti-umbrella!</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">So organisms can get water from air, food, or metabolism - but we can go them one better. There is an animal that doesn’t eat or drink during its entire adult life, can you imagine? O.K. – so its life is only five minutes long, but it doesn’t eat or drink during that five minutes.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Adult female sand burrowing mayflies (<i>Dolania Americana</i>) emerge from their water-borne larval form and seek two things, a male for mating, and a place to deposit her eggs. Since all larvae are evolved to mature at once, males are around in large numbers; problem 1 solved. And since they live near water, place to lay eggs are also plentiful; problem 2 solved. Within five minutes, her work is done and she dies – not a glamorous life.</span></div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQD5jNOkU9tFRqkZRwVd6fl0MRZRD-9B8D-xhQZk-oG_RnNWfswW85ise_HpelAqxBsc9DxD6BugKav1gAyism0Sv5ULcBjZvkW85Ngj_UeY291WxOIdDmteV5Eg2JDRyFHiN9MuwubzGE/s1600/6-Dolania+Americana.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQD5jNOkU9tFRqkZRwVd6fl0MRZRD-9B8D-xhQZk-oG_RnNWfswW85ise_HpelAqxBsc9DxD6BugKav1gAyism0Sv5ULcBjZvkW85Ngj_UeY291WxOIdDmteV5Eg2JDRyFHiN9MuwubzGE/s320/6-Dolania+Americana.jpg" width="320" /></a></td></tr>
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<span style="font-family: "cambria"; font-size: 11pt;">The American sand burrowing mayfly lives a year or more </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">as a larvae in the water, but when it metamorphoses into </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">the sexually mature form and leaves the water, 5 minutes </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">is all she gets. There may be species with shorter sexual </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">reproductive life span, but it would be hard to spot, and </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">harder to study. </span> </td></tr>
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<span style="font-family: "cambria"; font-size: 12pt;">Different species of mayfly live varying amounts of time – some live as adults for up to 2 days - oldtimers! But even if the mayfly wanted to invest some of their precious time in eating and drinking, they couldn’t do it. Adult mayfly mouthparts are <b>vestigial</b> (having become nonfunctional through evolution) and their digestive systems disappear as they mature. So in this biological case, a <u>lack</u> of form follows a <u>lack</u> of function. </span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">There is another crucial element of life that interacts with water, and ocean going organisms are intimately familiar with it. Salt is just as important for life as is water, but why? We will begin looking into the functions of salts and how they interact with water next time.</span><br />
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Physiological+and+biochemical+zoology+%3A+PBZ&rft_id=info%3Apmid%2F13130431&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Merriam%27s+kangaroo+rats+%28Dipodomys+merriami%29+voluntarily+select+temperatures+that+conserve+energy+rather+than+water.&rft.issn=1522-2152&rft.date=2003&rft.volume=76&rft.issue=4&rft.spage=522&rft.epage=32&rft.artnum=&rft.au=Banta+MR&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CEcology+%2F+Conservation%2CZoology%2C+Behavioral+Biology%2C+Anatomy%2C+Physiology%2C+Climate+Change%2C+Ecology">Banta MR (2003). Merriam's kangaroo rats (Dipodomys merriami) voluntarily select temperatures that conserve energy rather than water. <span style="font-style: italic;">Physiological and biochemical zoology : PBZ, 76</span> (4), 522-32 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/13130431" rev="review">13130431</a></span>
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<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+sports+sciences&rft_id=info%3Apmid%2F18828029&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=Estimating+changes+in+hydration+status+from+changes+in+body+mass%3A+considerations+regarding+metabolic+water+and+glycogen+storage.&rft.issn=0264-0414&rft.date=2008&rft.volume=26&rft.issue=12&rft.spage=1361&rft.epage=3&rft.artnum=&rft.au=King+RF&rft.au=Cooke+C&rft.au=Carroll+S&rft.au=O%27Hara+J&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CMedicine%2CHealth%2CBiochemistry%2C+Cell+Biology%2C+Physiology%2C+Metabolism%2C+Kinesiology">King RF, Cooke C, Carroll S, & O'Hara J (2008). Estimating changes in hydration status from changes in body mass: considerations regarding metabolic water and glycogen storage. <span style="font-style: italic;">Journal of sports sciences, 26</span> (12), 1361-3 PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/18828029" rev="review">18828029</a></span>
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<span style="font-family: "cambria"; font-size: 11pt;">For more information, classroom activities, and laboratories about water uptake, renal function, trichome, or mayflies:</span></div>
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<span style="font-family: "cambria"; font-size: x-small;">Animals that don’t drink –</span></div>
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<span style="font-size: x-small;"><a href="http://library.thinkquest.org/3500/polarbear.htm">http://library.thinkquest.org/3500/polarbear.htm</a></span><span style="font-family: "cambria"; font-size: x-small;"></span></div>
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<span style="font-size: x-small;"><a href="http://www.kidcyber.com.au/topics/koalas.htm">http://www.kidcyber.com.au/topics/koalas.htm</a></span><span style="font-family: "cambria"; font-size: x-small;"></span></div>
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<span style="font-size: x-small;"><a href="http://www.veganpeace.com/animal_facts/Frogs.htm">http://www.veganpeace.com/animal_facts/Frogs.htm</a></span><span style="font-family: "cambria"; font-size: x-small;"></span></div>
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<span style="font-size: x-small;"><a href="http://www.desertmuseum.org/kids/oz/long-fact-sheets/krat.php">http://www.desertmuseum.org/kids/oz/long-fact-sheets/krat.php</a></span><span style="font-family: "cambria"; font-size: x-small;"></span></div>
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<span style="font-size: x-small;"><a href="http://www.alicespringsdesertpark.com.au/kids/nature/mammals/mouse.shtml">http://www.alicespringsdesertpark.com.au/kids/nature/mammals/mouse.shtml</a></span></div>
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<span style="font-size: x-small;"><span style="font-family: "cambria";">Kidneys – </span></span></div>
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<span style="font-size: x-small;"><a href="http://www.youtube.com/watch?v=7nesHuVEe8M&feature=related">http://www.youtube.com/watch?v=7nesHuVEe8M&feature=related</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.comprehensive-kidney-facts.com/kidney-anatomy.html">http://www.comprehensive-kidney-facts.com/kidney-anatomy.html</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.youtube.com/watch?v=aQZaNXNroVY">http://www.youtube.com/watch?v=aQZaNXNroVY</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.khanacademy.org/video/the-kidney-and-nephron?playlist=Biology">http://www.khanacademy.org/video/the-kidney-and-nephron?playlist=Biology</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://oracle3927.tripod.com/nephron.htm">http://oracle3927.tripod.com/nephron.htm</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEAQFjAD&url=http%3A%2F%2Fwww.apsarchive.org%2Fdownload.cfm%3FsubmissionID%3D1785&ei=7-oST7rJL-qvsQL9q8CKBA&usg=AFQjCNGprOyj9oVkDNKowpCPpxK2D3HgUw">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEAQFjAD&url=http%3A%2F%2Fwww.apsarchive.org%2Fdownload.cfm%3FsubmissionID%3D1785&ei=7-oST7rJL-qvsQL9q8CKBA&usg=AFQjCNGprOyj9oVkDNKowpCPpxK2D3HgUw</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CD8QFjAC&url=http%3A%2F%2Flifesciences.envmed.rochester.edu%2Fcurriculum%2FSEPAClass%2F3.TEACHERKidneyDialysis7-23-09.pdf&ei=0OsST_DVL4STgwfJ_sS-BA&usg=AFQjCNFweWcQcIeROvktESpk7DoA_Jzu0Q">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CD8QFjAC&url=http%3A%2F%2Flifesciences.envmed.rochester.edu%2Fcurriculum%2FSEPAClass%2F3.TEACHERKidneyDialysis7-23-09.pdf&ei=0OsST_DVL4STgwfJ_sS-BA&usg=AFQjCNFweWcQcIeROvktESpk7DoA_Jzu0Q</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEcQFjAD&url=http%3A%2F%2Flifesciences.envmed.rochester.edu%2Fcurriculum%2FSEPAClass%2F2.STUDENTKidneyProblem7-23-09.pdf&ei=0OsST_DVL4STgwfJ_sS-BA&usg=AFQjCNFl-pKLn0G3-5Rmuky8CTrrJP43Ng">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CEcQFjAD&url=http%3A%2F%2Flifesciences.envmed.rochester.edu%2Fcurriculum%2FSEPAClass%2F2.STUDENTKidneyProblem7-23-09.pdf&ei=0OsST_DVL4STgwfJ_sS-BA&usg=AFQjCNFl-pKLn0G3-5Rmuky8CTrrJP43Ng</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.pbs.org/wgbh/nova/teachers/resources/subj_05_03.html">http://www.pbs.org/wgbh/nova/teachers/resources/subj_05_03.html</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=0CHgQFjAJ&url=http%3A%2F%2Fwww.apsarchive.org%2Fdownload.cfm%3FsubmissionID%3D1785&ei=0OsST_DVL4STgwfJ_sS-BA&usg=AFQjCNGprOyj9oVkDNKowpCPpxK2D3HgUw">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&ved=0CHgQFjAJ&url=http%3A%2F%2Fwww.apsarchive.org%2Fdownload.cfm%3FsubmissionID%3D1785&ei=0OsST_DVL4STgwfJ_sS-BA&usg=AFQjCNGprOyj9oVkDNKowpCPpxK2D3HgUw</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><span style="font-family: "cambria";">Aquaporins – </span></span></div>
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<span style="font-size: x-small;"><a href="http://www.ks.uiuc.edu/Research/aquaporins/">http://www.ks.uiuc.edu/Research/aquaporins/</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.vivo.colostate.edu/hbooks/molecules/aquaporins.html">http://www.vivo.colostate.edu/hbooks/molecules/aquaporins.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.aquaporins.org/">http://www.aquaporins.org/</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.ncbi.nlm.nih.gov/pubmed/11773613">http://www.ncbi.nlm.nih.gov/pubmed/11773613</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://scifair.org/news/chemistry-news/one-protein-two-channels-scientists-explain-mechanism-in-aquaporins.html">http://scifair.org/news/chemistry-news/one-protein-two-channels-scientists-explain-mechanism-in-aquaporins.html</a><span style="font-family: "cambria";"></span></span></div>
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<span style="font-size: x-small;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC4QFjAA&url=http%3A%2F%2Fwww.apsarchive.org%2Fdownload.cfm%3FsubmissionID%3D1912&ei=Wu0ST4TNKo7iggeYg6zMAw&usg=AFQjCNFxPFXm3XwoxYOlJB-lPX-oxAPJ_Q">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC4QFjAA&url=http%3A%2F%2Fwww.apsarchive.org%2Fdownload.cfm%3FsubmissionID%3D1912&ei=Wu0ST4TNKo7iggeYg6zMAw&usg=AFQjCNFxPFXm3XwoxYOlJB-lPX-oxAPJ_Q</a><span style="font-family: "cambria";"></span></span></div>
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<br /></div>
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<span style="font-size: x-small;"><span style="font-family: "cambria";">Trichomes – </span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.420magazine.com/forums/how-grow-marijuana/71982-what-trichomes-trichome-101-a.html">http://www.420magazine.com/forums/how-grow-marijuana/71982-what-trichomes-trichome-101-a.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.astrographics.com/GalleryPrintsIndex/GP2023.html">http://www.astrographics.com/GalleryPrintsIndex/GP2023.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.sbs.utexas.edu/mauseth/weblab/webchap9secretory/9.4-1.htm">http://www.sbs.utexas.edu/mauseth/weblab/webchap9secretory/9.4-1.htm</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://bromeliads.gardenwebs.net/trichomes.htm">http://bromeliads.gardenwebs.net/trichomes.htm</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.bsi.org/brom_info/what.html">http://www.bsi.org/brom_info/what.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://plantsinaction.science.uq.edu.au/edition1/?q=content/15-4-3-epiphytes">http://plantsinaction.science.uq.edu.au/edition1/?q=content/15-4-3-epiphytes</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CFMQFjAE&url=http%3A%2F%2Fcsusciencemethods.wikispaces.com%2Ffile%2Fview%2FFast_Plants_unit_LP&ei=r_AST_nvO8qrsAKp0dXcAw&usg=AFQjCNEIHT9dlpgkKb53N0BUbBCOyTsyLA">http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0CFMQFjAE&url=http%3A%2F%2Fcsusciencemethods.wikispaces.com%2Ffile%2Fview%2FFast_Plants_unit_LP&ei=r_AST_nvO8qrsAKp0dXcAw&usg=AFQjCNEIHT9dlpgkKb53N0BUbBCOyTsyLA</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
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<span style="font-size: x-small;"><span style="font-family: "cambria";">Mayflies - </span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://insects.tamu.edu/fieldguide/aimg3.html">http://insects.tamu.edu/fieldguide/aimg3.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.entm.purdue.edu/mayfly/">http://www.entm.purdue.edu/mayfly/</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.cirrusimage.com/ephemeroptera_mayflies.htm">http://www.cirrusimage.com/ephemeroptera_mayflies.htm</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.ucmp.berkeley.edu/arthropoda/uniramia/ephemeroptera.html">http://www.ucmp.berkeley.edu/arthropoda/uniramia/ephemeroptera.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.mayflyintheclassroom.org/">http://www.mayflyintheclassroom.org/</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.rectory-farm.org.uk/HTML_Files/Mayfly_Classroom.html">http://www.rectory-farm.org.uk/HTML_Files/Mayfly_Classroom.html</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://www.learnnc.org/lp/editions/mudcreek/6603">http://www.learnnc.org/lp/editions/mudcreek/6603</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://biofreshblog.com/2011/05/17/mayfly-in-the-classroom/">http://biofreshblog.com/2011/05/17/mayfly-in-the-classroom/</a><span style="font-family: "cambria";"></span></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: x-small;"><a href="http://dnr.wi.gov/org/land/er/biodiversity/index.asp?mode=info&Grp=18&SpecCode=IIEPH02010">http://dnr.wi.gov/org/land/er/biodiversity/index.asp?mode=info&Grp=18&SpecCode=IIEPH02010</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<span style="font-size: 11pt;"><a href="http://www.youtube.com/watch?v=7nesHuVEe8M&feature=related"></a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1tag:blogger.com,1999:blog-8136765635696545893.post-14444504337007874082016-08-10T06:00:00.000-04:002016-08-10T06:00:02.943-04:00Gimme Some Dihydrogen Monoxide<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh85wdj4KIiMkzSmZxD5jza6g8g2hWYpQ2dn-UpGpSYdQ6GYKc75UBK_cF5bqJJxfT66WXdMdv8dJLT2xCPHErzkPhcvC8-zsg6a0P0ftroh_wycYvz3C9_2UX0h2HhsrLxLBEE7I0hrG9N/s1600/thirsty-water-crisis.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh85wdj4KIiMkzSmZxD5jza6g8g2hWYpQ2dn-UpGpSYdQ6GYKc75UBK_cF5bqJJxfT66WXdMdv8dJLT2xCPHErzkPhcvC8-zsg6a0P0ftroh_wycYvz3C9_2UX0h2HhsrLxLBEE7I0hrG9N/s200/thirsty-water-crisis.jpg" width="195" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Birds need water just like the rest of us, </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">but beaks make it harder. They may suck </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">it up like a straw or scoop it up like a bucket, </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">or by leaning back and letting the rain fall in.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">At some point or another we've all said, “I’m about to die of thirst.” Of course we can only survive for a few short days without water, but do you know why? </span></div>
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<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Cells are full of salt water (<b>saline</b>), but are also crowded with proteins, carbohydrates and lipids (saline + organic molecules = <b>cytoplasm</b>). This suggests the importance of H<sub>2</sub>O, but it doesn’t say anything about the reasons behind its importance.</span></div>
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<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Water is the <b>solvent</b> (the liquid part of a solution), while the proteins and carbohydrates are the <b>solutes</b> (the solids dissolved in the solvent). Lipids (a type of fat) are insoluble in water; therefore, they are good for building cell membranes. They help keep what is in in, and what is out out. With a lipid membrane, our cytoplasm doesn't leak out on to the floor.</span></div>
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDtNXZCTmhEDN671W6FxzBXloVZsDTSSaW9gx-kE16WFAg4n6vH4aEnvEbd9Ap5jIfmLIFr1NZqc9RJQ8Ody48adeZALj9VLwQ0eBFiivmARP078c2OUmIn8NT5nrEzjzUHGoxjx70p-XU/s1600/Cell_cytoplasm-SPL.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="276" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDtNXZCTmhEDN671W6FxzBXloVZsDTSSaW9gx-kE16WFAg4n6vH4aEnvEbd9Ap5jIfmLIFr1NZqc9RJQ8Ody48adeZALj9VLwQ0eBFiivmARP078c2OUmIn8NT5nrEzjzUHGoxjx70p-XU/s400/Cell_cytoplasm-SPL.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
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<span style="font-family: "cambria"; font-size: 11pt;">Cytoplasm isn’t water plus some organelles. As shown in </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">this electron micrograph, it is more like a gel, packed </span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">with organelles, proteins, minerals, sugars, and nucleic</span></div>
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<span style="font-family: "cambria"; font-size: 11pt;">acids. There is water, but just enough to separate the other</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">constituents. </span>Photomicrograph credit: Dr. Jeremy Burgess/Science </div>
<span style="font-size: x-small;"><span style="font-family: "cambria";">Photo Library.</span></span> </td></tr>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">The intracellular solutes are surrounded by water. It’s like the green jello with pineapple that your Aunt brought every Christmas, except that it's packed to the gills with pineapple. Cytoplasm is more crowded than the public pool on a 104˚F day when the ice cream vendors have gone on strike. In some cases, there may only be a few molecules of water separating different cellular components, but this water layer is crucial.</span></div>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Water is the solvent in which most cellular reactions take place. Water is made up of an acid (H<sup>+</sup>) and a base (hydroxyl, OH<sup>-</sup>). Together, they are two hydrogen atoms and one oxygen, H<sub>2</sub>O! Having the H<sup>+</sup> around keeps the bases in check, while the OH<sup>-</sup> keeps the acids in check. This helps keep the cytoplasmic pH within a small range (<b>buffers</b> it), about 7.35-7.45. Buffering the cytoplasm ensures that that reactions proceed in the proper direction and at the proper rate.</span></div>
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<span style="font-family: "cambria"; font-size: 12pt;">Water transports materials within the cell, from cell to cell, and through the blood and lymph. The partial negative and positive charges, the high surface tension, and the cohesive properties of water make it good at its jobs. </span></div>
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<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihOMaullIU-X7KDbemGM0KKipLqSHOiLQ2OcHf98fj1YHSA6NO9GYOZa7OMNB1OshkO4CNUZ_SpB5EcUe4ip0HQV7RgCbuCO6igihU0c7D-QbCgVnuIpuJ-4Cr5gEZ1elWRh2nd0eBTaz1/s1600/capillarity.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="199" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihOMaullIU-X7KDbemGM0KKipLqSHOiLQ2OcHf98fj1YHSA6NO9GYOZa7OMNB1OshkO4CNUZ_SpB5EcUe4ip0HQV7RgCbuCO6igihU0c7D-QbCgVnuIpuJ-4Cr5gEZ1elWRh2nd0eBTaz1/s200/capillarity.jpg" width="200" /></a></td></tr>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Water being sucked up in a capillary tube </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">uses cohesion (water sticking to water) and </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">adhesion (water sticking to the glass tube). </span></div>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Water likes to bond to itself (<b>cohesion</b>) via <b>hydrogen bonds</b> formed between the positive H<sup>+</sup>’s of one water molecule and the negative OH<sup>-</sup>‘s of two others. Cohesion is what makes water form drops as it rains, and what gives water its strong <b>surface tension</b>. Surface tension is why some insects can land on water and take off again. Water striders (family Gerridae), walk on water and you can actually see the depression in the surface, like when you stand on your bed. They are helped out in this endeavor by <b>hydrophobic</b> (water-fearing) tiny hairs on their legs and feet.</span></div>
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<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Water also likes to hydrogen bond other surfaces; this is called <b>adhesion</b>. If you pour water into a small diameter glass, you can see it cling to the side (<b>meniscus</b>, Greek for crescent), and even seem to rise up the side of the glass </span><span style="font-family: "cambria"; font-size: 12pt;">(see the image above)</span><span style="font-family: "cambria"; font-size: 12pt;">. If the glass tube is narrow enough, like in a capillary tube, the water will climb up the tube against gravity. The force that drives this is adhesion. </span></div>
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<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-tyHCD27_UkHc0gO2M9568z2EFYgcjPulTgkSO2DEJm9lgRSti2q5SVHORXfzo2a5V4EdPeDFNEvrQxfrV4LXKLkUcdF81ipnL1e3xnNyD3DayyeDXku5gpSM-DK3RioxT77ZKTYrTygw/s1600/water+bug+2.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="256" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-tyHCD27_UkHc0gO2M9568z2EFYgcjPulTgkSO2DEJm9lgRSti2q5SVHORXfzo2a5V4EdPeDFNEvrQxfrV4LXKLkUcdF81ipnL1e3xnNyD3DayyeDXku5gpSM-DK3RioxT77ZKTYrTygw/s320/water+bug+2.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Water striders spread their weight over a large area to</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">reduce their pressure on the water. They are also helped</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">by the hydrophobic proteins on their legs. But mostly, the cohesive </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">force of the water raises the surface tension so the strider</span></div>
<span style="font-family: "cambria"; font-size: 11pt;">remains on the surface.</span> </td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">The adhesive force is driven by the bipolar (a negative end and a positive end) nature of water, just as with cohesion. The positive H<sup>+</sup> is attracted to any negative molecules, and the negative OH<sup>-</sup> is attracted to anything positive. Together, they are attracted to most everything, not just other water molecules. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Hydrogen bonding and the adhesion and cohesion they produce are important for plants. How does water absorbed by a redwood’s roots get to its leaves way up high? The mechanism has several features, the most important of which is suction. When water in the leaves evaporates, it creates negative pressure that actually pulls the water up from the roots through the plants vessels. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">The negative pressure alone isn’t strong enough to keep the water moving against gravity, but when you add in the cohesion of water molecules to one another, and adhesion of the water molecules to the sides of the vessels, it all works out. The sum total of these actions is called <b>transpiration</b>, and is responsible for moving water against gravity in plants. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Water also participates in many cellular reactions, most famously photosynthesis. During the <b>Calvin cycle</b> of photosynthesis (dark reactions) glucose is produced, water is split into hydrogen atoms that are incorporated into the growing carbohydrate and gaseous oxygen (O<sub>2</sub>) that is released. It is this transformation of water to gas that drives transpiration. In <b>cellular respiration</b>, when carbohydrates are used to produce chemical energy (ATP), the exact opposite occurs – water is formed from oxygen and hydrogen.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Other cellular reactions, such as the <b>hydrolysis</b> (hydro = water and lyse = split) of fats or proteins are occurring inside cells all the time. In these types of reactions, a water molecule is split into H and OH while the target molecule is also split in two; one part gains a hydrogen and the other gains a hydroxyl group. This is crucial for the normal degradation of cellular proteins by protease enzymes, amongst other things. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">If that wasn’t enough, water acts as temperature buffer, helping organisms hold a more constant temperature. Water does not warm up fast and it does not cool down fast; it tends to keep an even temperature. It has a high <b>specific heat</b> (1 calorie/gram C˚), meaning that you must add a lot of energy in order to change its temperature. Water’s high specific heat evens out temperature fluctuations in the body and allows reactions to proceed in a controlled fashion.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Finally, many organisms use water pressure to hold their form, an example of the turgor pressure we learned about several weeks ago (<span style="background: none repeat scroll 0% 0% rgb(255, 255, 255);"><a href="http://biologicalexceptions.blogspot.com/2016/02/plants-that-dont-sleep-will-take-dirt.html" target="_blank">Plants That Don’t Get A Good Night’s Sleep</a></span>). For instance, you return home from a trip to find your plants have turned brown and are drooping in their pots. Your goldfish are belly up, and the expensive six-pack in your fridge is now a two pack – the neighbor you asked to look after them did a bang up job. If you’re lucky, the plants stand back up a few hours after a good soaking, especially if you fertilize them with your goldfish carcasses. Your plants need the water for everything we have discussed, but also because the water pressure in the cells keeps them the plant stem and leaves standing rigid. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCQheS6rh5cEWrBR8Q_519Fmsgd7kJIIRox9S5yWziwcPnj6FrZfv_GT9qNPnkBatS_BQ2yVHs4WcTZzhu8q_Dmxt7yuLDctjXRFh-axf3iZY85aKd9DtGDH3PW4gfYj-dnorF9dFh0HHU/s1600/tube+feet.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="214" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCQheS6rh5cEWrBR8Q_519Fmsgd7kJIIRox9S5yWziwcPnj6FrZfv_GT9qNPnkBatS_BQ2yVHs4WcTZzhu8q_Dmxt7yuLDctjXRFh-axf3iZY85aKd9DtGDH3PW4gfYj-dnorF9dFh0HHU/s320/tube+feet.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">The tube feet of starfish and other eichinoderms have a </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">suction cup on the end of the <b>podia</b>. The internal portion</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">is the <b>ampulla</b>, the tube that holds water to regulate the</span></div>
<span style="font-family: "cambria"; font-size: 11pt;">tube movement.</span> </td></tr>
</tbody></table>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">In a similar fashion, starfish store and move water through a series of hollow tubes to form a <b>hydrostatic skeleton</b>. In the general sense, this type of skeleton is any fluid filled cavity surrounded by muscle, in which the actions of the muscles work against the fluid pressure in the cavity. Worms, and many other invertebrates have this type of support system. </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">But starfish take the concept a bit further. Not only is water used to maintain the form and structure of the animal; it makes up the <b>water vascular system</b> for locomotion (tube feet), food transport, and respiration. By moving water in and out of specific tubes in the different arms, the muscles contract and extend the tube feet, pushing them against a surface. The movement of water in and out of the tube feet is also the primary way to move oxygen into the tissues of the starfish, and the water pressure can be used to evert </span><span style="font-family: "cambria"; font-size: 12pt;">their stomach</span><span style="font-family: "cambria"; font-size: 12pt;"> (it will protrude out their mouth and turn inside out) to surround and engulf food. Ugh!</span><br />
<br />
<span style="font-family: "cambria"; font-size: 12pt;">
</span><br />
<div class="MsoNormal">
Many types of animals use hydrostatic skeletons, where the
pressure of water substitutes for a rigid skeleton. Muscular movements are
generated against the in agonist/antagonist form against the pressure of the
water, using muscular fibers positioned in several planes. <a href="http://jeb.biologists.org/content/215/8/1247.long"><span style="background-color: white;"><span style="background-attachment: scroll; background-clip: border-box; background-image: none; background-origin: padding-box; background-position: 0% 0%; background-repeat: repeat; background-size: auto auto;">A recent review by William M. Kier</span></span></a>
demonstrates how the hydrostatic skeletons and muscular arrangements of several
different animals work to generate stiffness as well as movement.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
For instance, in the tube feet of the starfish, <i style="mso-bidi-font-style: normal;">Ludia clathrata</i>, muscular fibers are
oriented in longitudinal and circular directions, allowing for extrusion and
contraction. But he also discusses the connective tissue fibers that are just
as important for the limiting of movement and generation of tension.</div>
</div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">We always knew water was crucial for life, and now we know why. Its importance is reinforced when you consider how much water there is in different organisms. Humans are about 60% water by mass, but it varies from person to person. Younger children are normally have a slightly higher percentage of water, maybe 70%, while morbidly obese people have much less water, remember that fat is stored in the absence of water (</span><span style="background: none repeat scroll 0% 0% rgb(255 , 255 , 255); font-family: "cambria"; font-size: 12pt;"><a href="http://biologicalexceptions.blogspot.com/2016/07/is-it-hot-in-here-or-is-it-just-my.html" target="_blank">Is it Hot in Here or is it Just My Philodendron</a>?</span><span style="font-family: "cambria"; font-size: 12pt;">).</span><span style="font-family: "cambria"; font-size: 12pt;"> </span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqNJc-aahtuFmw0jpGA8CfO4qsKybjXsELgX6jOBKofJTAzy9iVvMiKCzmo1eA_SzzO4xuZVj5hYGnaLwiRY48vD9Ibg7mbpGQ8gH2c4e2TAMfNsAcGW6B1RPBNs688VTfRCVCTMPpLF3P/s1600/golden_barrel_cactus.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqNJc-aahtuFmw0jpGA8CfO4qsKybjXsELgX6jOBKofJTAzy9iVvMiKCzmo1eA_SzzO4xuZVj5hYGnaLwiRY48vD9Ibg7mbpGQ8gH2c4e2TAMfNsAcGW6B1RPBNs688VTfRCVCTMPpLF3P/s320/golden_barrel_cactus.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><br />
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">The golden barrel cactus has ribs that can expand and </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">contract, depending on the hydration state of the plant. </span></div>
<span style="font-family: "cambria"; font-size: 11pt;">It is also called a mother-in-law’s cushion….that’s just mean.</span> </td></tr>
</tbody></table>
<div class="MsoNormal">
<span style="font-family: "cambria"; font-size: 12pt;">Plants require even more water. Cactuses can be more than 90% water after a good rainfall. The places where cacti grow have variable water availability, so when water is present, they must take advantage. The endangered golden barrel cactus has ribs that can expand to take in more water. In addition, the golden barrel cactus is round to reduce surface area and has a thick waxy surface, both of which reduce water loss.</span> </div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Despite these dehydration prevention measures, cacti still lose water over time, and it might not be replaced for a long time. Therefore, cacti have evolved mechanisms to withstand the loss of almost 60% of their water without any negative ramifications. In this area, they are the exception. Typical flowers and trees can only withstand a 20% water loss without damage; however, this is still much better than humans can do.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">No matter what your personal water percentage might be, you can only afford to lose about 5% of your water without suffering symptoms. At mild levels of dehydration (5%), you may feel groggy or get a headache. Higher levels of water loss will bring tingling in the muscles, nausea, and confusion. If the loss reaches 10-15%, there can be muscle spasms, delirium, and the kidneys may be permanently damaged (if water loss is held for a sufficient period). Held above 15%, dehydration is usually fatal. However, athletes can lose up to 30% of their body water in the short term, but it must be replenished immediately so that performance or normal function will not be compromised.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">When we say normal function, we mean those functions of water we have mentioned, but also several others we haven’t. Water, along with surfactant proteins, works to keep our lungs absorbing oxygen. Water lubricates our joints and tissues to avoid friction damage. People with <b>xerostomia</b> (Greek, xero = dry and stoma = mouth) or <b>xerophthalmia</b> (dry eyes) use artificial saliva or tears to prevent damage to mucous membranes. Finally, water acts as a cushion, absorbing pressure and force to protect our organs from traumatic damage, like a punch to the gut.</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 12pt;">Damage can come in many forms when water is low, so all living organisms require water intake to function and remain safe, right?……Or is just <b>most</b> organisms? Next time.</span><br />
<br />
<br />
<span class="Z3988" title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.jtitle=Journal+of+Experimental+Biology&rft_id=info%3Adoi%2F10.1242%2Fjeb.056549&rfr_id=info%3Asid%2Fresearchblogging.org&rft.atitle=The+diversity+of+hydrostatic+skeletons&rft.issn=0022-0949&rft.date=2012&rft.volume=215&rft.issue=8&rft.spage=1247&rft.epage=1257&rft.artnum=http%3A%2F%2Fjeb.biologists.org%2Fcgi%2Fdoi%2F10.1242%2Fjeb.056549&rft.au=Kier%2C+W.&rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CAnatomy%2C+Biophysics%2C+Cell+Biology%2C+Zoology">Kier, W. (2012). The diversity of hydrostatic skeletons <span style="font-style: italic;">Journal of Experimental Biology, 215</span> (8), 1247-1257 DOI: <a href="http://dx.doi.org/10.1242/jeb.056549" rev="review">10.1242/jeb.056549</a></span>
<br />
<br /></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria";">For more information, classroom activities, or laboratories about water in biology, the properties of water, transpiration, or the Calvin cycle, see:</span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">Water in biology –</span></div>
<div style="margin: 0.1pt 0in;">
<a href="http://www.amnh.org/exhibitions/water/?section=lifeinwater&page=lifeinwater_f"><span style="font-size: 11pt;">http://www.amnh.org/exhibitions/water/?section=lifeinwater&page=lifeinwater_f</span></a></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.everydayhealth.com/water-health/water-body-health.aspx">http://www.everydayhealth.com/water-health/water-body-health.aspx</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "times";"><a href="http://www.coastalcoolers.com/body.pdf"><span style="font-style: normal;">www.coastalcoolers.com/</span><b><span style="font-style: normal;">body</span></b><span style="font-style: normal;">.pdf</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.chemcraft.net/wbody.html">http://www.chemcraft.net/wbody.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.rawfoodexplained.com/water/waters-role-in-the-body.html">http://www.rawfoodexplained.com/water/waters-role-in-the-body.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.weightlossunit.com/Pages/Healthy_eating_articles/role_of_water_in_human_body.html">http://www.weightlossunit.com/Pages/Healthy_eating_articles/role_of_water_in_human_body.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">properties of water –</span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.uni.edu/~iowawet/H2OProperties.html">http://www.uni.edu/~iowawet/H2OProperties.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://faculty.rcoe.appstate.edu/goodmanjm/asuscienceed/background/waterdrops/waterdrops.html">http://faculty.rcoe.appstate.edu/goodmanjm/asuscienceed/background/waterdrops/waterdrops.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html">http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://daphne.palomar.edu/jthorngren/water.htm">http://daphne.palomar.edu/jthorngren/water.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.youtube.com/watch?v=LrNwcxMWJ68">http://www.youtube.com/watch?v=LrNwcxMWJ68</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.physicalgeography.net/fundamentals/8a.html">http://www.physicalgeography.net/fundamentals/8a.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://propertiesofwater.org/">http://propertiesofwater.org/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.watereducation.utah.gov/WaterScience/Properties/default.asp">http://www.watereducation.utah.gov/WaterScience/Properties/default.asp</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://aquarius.nasa.gov/prop_fresh_sea.html">http://aquarius.nasa.gov/prop_fresh_sea.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "times";"><a href="http://www.uas.alaska.edu/attac/ampdf/activity3.pd"><span style="font-style: normal;">www.uas.alaska.edu/attac/ampdf/</span><b><span style="font-style: normal;">activity</span></b><span style="font-style: normal;">3.pd</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "times";"><a href="http://www.edinformatics.com/math_science/water_ice.htm"><span style="font-style: normal;">www.edinformatics.com/math_science/</span><b><span style="font-style: normal;">water</span></b><span style="font-style: normal;">_ice.htm</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">transpiration – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://ga.water.usgs.gov/edu/watercycletranspiration.html">http://ga.water.usgs.gov/edu/watercycletranspiration.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Transpiration.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Transpiration.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.phschool.com/science/biology_place/labbench/lab9/intro.html">http://www.phschool.com/science/biology_place/labbench/lab9/intro.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.biologymad.com/resources/transpiration.swf">http://www.biologymad.com/resources/transpiration.swf</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://extension.oregonstate.edu/mg/botany/transpir.html">http://extension.oregonstate.edu/mg/botany/transpir.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.eoearth.org/article/Transpiration">http://www.eoearth.org/article/Transpiration</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.youtube.com/watch?v=U4rzLhz4HHk">http://www.youtube.com/watch?v=U4rzLhz4HHk</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<cite><span style="font-family: "times";"><a href="http://www.ucar.edu/learn/1_4_2_18t.htm"><span style="font-style: normal;">www.ucar.edu/learn/1_4_2_18t.htm</span></a></span></cite></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.sciencebob.com/blog/?p=162">http://www.sciencebob.com/blog/?p=162</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://beckyboop.wordpress.com/2011/03/22/plant-transpiration-lesson-plan/">http://beckyboop.wordpress.com/2011/03/22/plant-transpiration-lesson-plan/</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.learnnc.org/lp/pages/3600">http://www.learnnc.org/lp/pages/3600</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<br /></div>
<div style="margin: 0.1pt 0in;">
<span style="font-family: "cambria"; font-size: 11pt;">calvin cycle – </span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.science.smith.edu/departments/Biology/Bio231/calvin.html">http://www.science.smith.edu/departments/Biology/Bio231/calvin.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.bio.umass.edu/biology/conn.river/calvin.html">http://www.bio.umass.edu/biology/conn.river/calvin.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html">http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.youtube.com/watch?v=_NIhg1qa_L0">http://www.youtube.com/watch?v=_NIhg1qa_L0</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.khanacademy.org/video/photosynthesis---calvin-cycle?playlist=Biology">http://www.khanacademy.org/video/photosynthesis---calvin-cycle?playlist=Biology</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CalvinCycle.html">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CalvinCycle.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://sites.bio.indiana.edu/~hangarterlab/courses/b373/lecturenotes/photosyn/carbon/c3.html">http://sites.bio.indiana.edu/~hangarterlab/courses/b373/lecturenotes/photosyn/carbon/c3.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/dark.htm">http://rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/dark.htm</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<div style="margin: 0.1pt 0in;">
<span style="font-size: 11pt;"><a href="http://www.johnkyrk.com/photosynthesisdark.html">http://www.johnkyrk.com/photosynthesisdark.html</a></span><span style="font-family: "cambria"; font-size: 11pt;"></span></div>
<span style="font-family: "cambria"; font-size: 11pt;"><a href="http://www.educationalrap.com/song/photosynthesis.html">http://www.educationalrap.com/song/photosynthesis.html</a></span>Anonymoushttp://www.blogger.com/profile/00419768882341300420noreply@blogger.com1