carbon fixation https://scienceblogs.com/ en Carboxysomes in a row https://scienceblogs.com/oscillator/2010/03/13/carboxysome-in-a-row <span>Carboxysomes in a row</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p><a href="http://scienceblogs.com/oscillator/2010/03/bacterial_organelles.php">Carboxysomes</a> are small compartments inside photosynthetic bacteria where the machinery for capturing carbon dioxide is concentrated. You can see carboxysomes and their characteristic virus-like shape when you look at slices of these bacteria under an electron microscope:</p> <p><a href="http://en.wikipedia.org/wiki/Carboxysome"><img src="http://scienceblogs.com/oscillator/wp-content/blogs.dir/343/files/2012/04/i-afd6d3980037f860bd06e9a242ead26c-Carboxysomes_EM-thumb-510x185-42568.jpg" alt="i-afd6d3980037f860bd06e9a242ead26c-Carboxysomes_EM-thumb-510x185-42568.jpg" /></a><a href="http://hms.harvard.edu/public/news/2010/030410_silver/index.html"><img src="http://scienceblogs.com/oscillator/wp-content/blogs.dir/343/files/2012/04/i-eca5a08a696ac800334faeee403d246e-psa-thumb-250x142-42569.jpg" alt="i-eca5a08a696ac800334faeee403d246e-psa-thumb-250x142-42569.jpg" /></a>Until recently, no one had looked at carboxysomes under the microscope in cells that were still alive. My labmates Dave and Bruno developed a way to label carboxysomes with fluorescent proteins and track them under a microscope as the cells grow, and their <a href="http://www.sciencemag.org/cgi/content/abstract/327/5970/1258">amazing paper</a> in <em>Science</em> details some of the fascinating systems they discovered about how carboxysomes are controlled. </p> <p><img src="http://scienceblogs.com/oscillator/wp-content/blogs.dir/343/files/2012/04/i-ab65676e3b2e28a8d3c0082199b5a676-knockouts.png" alt="i-ab65676e3b2e28a8d3c0082199b5a676-knockouts.png" /> They noticed something very interesting right away: the carboxysomes in live cells are all lined up, evenly spaced, down the central axis of the rod-shaped bacteria. They hypothesized that there must be something holding the carboxysomes in place, preventing them from diffusing through the cytoplasm. All bacteria have a "skeleton," a mesh of proteins that maintains their shape, helps them divide, and can hold chromosomes and other cellular parts in place. When they deleted one of these mesh proteins out of the genome of the photosynthetic bacteria they saw that the cells would become rounder, not able to hold their shape as well, and that the carboxysomes weren't evenly spaced any more (figure B). When they knocked out a different skeleton-associated protein, <em>parA</em>, they saw that it seemed to exert special control over the carboxysomes. Deleting this gene allowed the cells to stay rod-shaped, but the carboxysomes weren't lined up anymore (figure C).</p> <p>In the mutants without <em>parA</em> and no even carboxysome spacing, sometimes when a cell divided, one of its daughter cells wouldn't get any carboxysomes. Without the machinery to capture carbon dioxide, the cell grew much slower until it was able to get enough protein together to make a new carboxysome. In the video below you can see this happening. The red arrow points to a cell that gets no carboxysomes after division, and the white arrow points at its sister cell that got them all. The empty cell doesn't divide again until it forms carboxysomes (the green dots), while the cell that got the carboxysomes has already divided by that time. This shows why the cell would invest so much energy holding the carboxysomes in place; without even spacing a certain number of cells wouldn't be able to grow at the optimal speed, decreasing the fitness of the whole population.</p> <object width="450" height="300"> <param name="movie" value="http://hms.harvard.edu/public/news/2010/030410_silver/player.swf?xmlFile=http://hms.harvard.edu/public/news/2010/030410_silver/custom.xml&amp;imagePath=http://hms.harvard.edu/public/news/2010/030410_silver/img/video2.jpg&amp;videoPath=http://hms.harvard.edu/public/news/2010/030410_silver/silver2.mov&amp;autoStart=false&amp;volAudio=60&amp;newWidth=480&amp;newHeight=385&amp;disableMiddleButton=false&amp;playSounds=true&amp;soundBarColor=0x0066FF&amp;barColor=0x0066FF&amp;barShadowColor=0x91BBFB&amp;subbarColor=0xffffff" /><param name="allowFullScreen" value="true" /><embed src="http://hms.harvard.edu/public/news/2010/030410_silver/player.swf?xmlFile=http://hms.harvard.edu/public/news/2010/030410_silver/custom.xml&amp;imagePath=http://hms.harvard.edu/public/news/2010/030410_silver/img/video2.jpg&amp;videoPath=http://hms.harvard.edu/public/news/2010/030410_silver/silver2.mov&amp;autoStart=false&amp;volAudio=60&amp;newWidth=480&amp;newHeight=385&amp;disableMiddleButton=false&amp;playSounds=true&amp;soundBarColor=0x0066FF&amp;barColor=0x0066FF&amp;barShadowColor=0x91BBFB&amp;subbarColor=0xffffff" type="application/x-shockwave-flash" allowfullscreen="true" width="450" height="300"></embed></object><p> When they fluorescently tagged <em>parA</em> in wild type cells, they saw something amazing: this "skeleton" protein isn't just a static structure that the carboxysomes cling too, but an oscillating wave, ping-ponging back and forth down the length of the bacteria. As the wave moves through the cell <em>parA</em> makes sure that the carboxysomes are evenly spaced along the whole axis. In other species of bacteria, this skeleton wave can control the even spacing of genetic material along the length of the cell or keeps proteins associated with the tips of rod-shaped bacteria where they belong. You can see the wave traveling through the cell in the second video, where the carboxysomes are labeled in red and the wave protein in green.</p> <object width="450" height="300"> <param name="movie" value="http://hms.harvard.edu/public/news/2010/030410_silver/player.swf?xmlFile=http://hms.harvard.edu/public/news/2010/030410_silver/custom.xml&amp;imagePath=http://hms.harvard.edu/public/news/2010/030410_silver/img/video1.jpg&amp;videoPath=http://hms.harvard.edu/public/news/2010/030410_silver/silver1.mov&amp;autoStart=false&amp;volAudio=60&amp;newWidth=480&amp;newHeight=385&amp;disableMiddleButton=false&amp;playSounds=true&amp;soundBarColor=0x0066FF&amp;barColor=0x0066FF&amp;barShadowColor=0x91BBFB&amp;subbarColor=0xffffff" /><param name="allowFullScreen" value="true" /><embed src="http://hms.harvard.edu/public/news/2010/030410_silver/player.swf?xmlFile=http://hms.harvard.edu/public/news/2010/030410_silver/custom.xml&amp;imagePath=http://hms.harvard.edu/public/news/2010/030410_silver/img/video1.jpg&amp;videoPath=http://hms.harvard.edu/public/news/2010/030410_silver/silver1.mov&amp;autoStart=false&amp;volAudio=60&amp;newWidth=480&amp;newHeight=385&amp;disableMiddleButton=false&amp;playSounds=true&amp;soundBarColor=0x0066FF&amp;barColor=0x0066FF&amp;barShadowColor=0x91BBFB&amp;subbarColor=0xffffff" type="application/x-shockwave-flash" allowfullscreen="true" width="450" height="300"></embed></object><p> With a deeper understanding of the cell biology of the carboxysomes and how they are controlled in the cell, as well as the genetic tools that Bruno and Dave developed for putting the fluorescent proteins into the photosynthetic bacteria, synthetic biologists in our lab and others will be better poised to engineer the carboxysomes for any number of synthetic purposes, to design novel bacterial micro-factories.</p> </div> <span><a title="View user profile." href="/author/cagapakis" lang="" about="/author/cagapakis" typeof="schema:Person" property="schema:name" datatype="">cagapakis</a></span> <span>Sat, 03/13/2010 - 06:10</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/bacteria" hreflang="en">bacteria</a></div> <div class="field--item"><a href="/tag/friends" hreflang="en">friends</a></div> <div class="field--item"><a href="/tag/papers" hreflang="en">papers</a></div> <div class="field--item"><a href="/tag/photosynthesis" hreflang="en">photosynthesis</a></div> <div class="field--item"><a href="/tag/research" hreflang="en">Research</a></div> <div class="field--item"><a href="/tag/carbon-fixation" hreflang="en">carbon fixation</a></div> <div class="field--item"><a href="/tag/carboxysome" hreflang="en">carboxysome</a></div> <div class="field--item"><a href="/tag/research-blogging-0" hreflang="en">research blogging</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-2493514" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268531632"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Very well explained.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493514&amp;1=default&amp;2=en&amp;3=" token="MzUrnUdhWT5x65U3tjRRpq9TNfTZyBGCbjraKFHn_3I"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Art (not verified)</span> on 13 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493514">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493515" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268702208"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Excellent blog, i am jealous of you students because you have great writing skills, keep it up, Greetings form Mexico.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493515&amp;1=default&amp;2=en&amp;3=" token="o2orC0hRiM55Z3rqASSMnkof5bu4UicgR3hVpbp1ONc"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">MSemán (not verified)</span> on 15 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493515">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493516" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1307328971"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Respected Sir,</p> <p>For my research work i need to isolate carboxysome from cyanobacteria please sent the protocol for carboxysome isolation</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493516&amp;1=default&amp;2=en&amp;3=" token="9o6DXi9aC7wvBnwMHAb2k1x8iFDdVktgIz3rpMVlInU"></drupal-render-placeholder> </div> <footer> <em>By <a rel="nofollow" href="http://scienceblogs.com/mt/pings/133382" lang="" typeof="schema:Person" property="schema:name" datatype="">Meenakshi (not verified)</a> on 05 Jun 2011 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493516">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/oscillator/2010/03/13/carboxysome-in-a-row%23comment-form">Log in</a> to post comments</li></ul> Sat, 13 Mar 2010 11:10:54 +0000 cagapakis 146861 at https://scienceblogs.com Bacterial "Organelles" https://scienceblogs.com/oscillator/2010/03/10/bacterial-organelles <span>Bacterial &quot;Organelles&quot;</span> <div class="field field--name-body field--type-text-with-summary field--label-hidden field--item"><p><a href="http://en.wikipedia.org/wiki/Organelle"><img alt="cell organelles.png" src="http://scienceblogs.com/oscillator/assets_c/2010/03/cell organelles-thumb-250x177-42351.png" width="250" height="177" class="mt-image-left" style="float: left; margin: 0 20px 20px 0;" /></a>Animal cells are made up of many smaller membrane-bound compartments called organelles that perform highly specialized functions necessary for life. Incredibly, several of these organelles have been shown to be evolutionarily related to free-living bacteria, captured and incorporated inside a larger cell billions of years ago in a complex mutually beneficial relationship, known as <a href="https://www.socgenmicrobiol.org.uk/pubs/micro_today/pdf/110406.pdf">endosymbiosis</a> (a partnership between two species where one of the species is <em>inside</em> the other). The mitochondria that power our cells, generating energy by breaking down sugars are in fact relatives of regular old bacteria, even having retained some bacterial genes that they replicate on their own. In some (very very rare) cases, the bacteria-ness of your own mitochondria can actually be bad for you, <a href="http://www.nature.com/nature/journal/v464/n7285/full/nature08780.html">activating an aggressive immune response </a>after a serious trauma releases the contents of lots of mitochondria into the bloodstream!</p> <p><a href="http://en.wikipedia.org/wiki/Bacteria"><img src="http://scienceblogs.com/oscillator/wp-content/blogs.dir/343/files/2012/04/i-e514a6c2edc41d6acdc554fd5392dd83-494px-Average_prokaryote_cell-_en.svg-thumb-250x203-42353.png" alt="i-e514a6c2edc41d6acdc554fd5392dd83-494px-Average_prokaryote_cell-_en.svg-thumb-250x203-42353.png" /></a>Bacteria themselves are much smaller and much simpler cells, performing many of the same cellular functions without the spatial organization of organelles, all the cell's enzymes and genetic material are instead floating freely in the cell. Some types of bacteria, however, do have compartments that have specialized functions, separating certain enzymatic activities from the rest of the cytoplasm. These compartments are surrounded by a protein shell, not a membrane, so they aren't <em>technically</em> organelles, but they're still pretty amazing. </p> <p>Many species of photosynthetic bacteria (the precursor to the chloroplast organelle that makes plants photosynthetic) have protein-bound compartments that separate the carbon dioxide capturing machinery from the rest of the cell, called <a href="http://en.wikipedia.org/wiki/Carboxysome">carboxysomes</a>. The enzyme that captures the carbon dioxide and turns its carbon atoms into chemical forms that the cell can use is called <a href="http://en.wikipedia.org/wiki/RuBisCO">RuBisCO</a> and it kind of sucks. Every carbon atom in a photosynthetic cell comes from this enzyme's function, but the reaction happens much much slower than most enzymatic reactions and if there's too much oxygen around it doesn't happen at all. In the carboxysome, RuBisCO is so tightly packed that oxygen can barely fit through the cracks, and the high concentration of the enzyme can help to overcome some of the inefficiency of the reaction. The carboxysome protein shell is made up of interconnecting proteins shaped like hexagons and pentagons that link together to form a complex polygon, kind of like a soccer ball. </p> <p><a href="http://en.wikipedia.org/wiki/Carboxysome"><img src="http://scienceblogs.com/oscillator/wp-content/blogs.dir/343/files/2012/04/i-8a344bfbfd6fb2dc0fb0509df533fb4c-800px-Carboxysome-thumb-510x194-42357.png" alt="i-8a344bfbfd6fb2dc0fb0509df533fb4c-800px-Carboxysome-thumb-510x194-42357.png" /></a><a href="http://en.wikipedia.org/wiki/Phage"><img src="http://scienceblogs.com/oscillator/wp-content/blogs.dir/343/files/2012/04/i-03255abd191187ea01447beb19d1af8f-512px-Phage-thumb-200x234-42364.jpg" alt="i-03255abd191187ea01447beb19d1af8f-512px-Phage-thumb-200x234-42364.jpg" /></a>This soccer-ball protein geometry is also used by some species of <a href="http://en.wikipedia.org/wiki/Phage">viruses</a> to form a protective shell. Some carboxysomes have a geometry that is <a href="http://aem.asm.org/cgi/reprint/67/12/5351">more complex than the standard icosahedral viral capsid</a>, indicating that carboxysomes may have not actually originated from the same common ancestor as the virus, but that their similarity is the result of <a href="http://en.wikipedia.org/wiki/Convergent_evolution">convergent evolution</a>. However, the question of whether carboxysomes are the result of endosymbiosis between bacteria and viruses that have evolved over billions of years is <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2267389/">still open</a>. This matryoshka doll concept of evolution and cellular substructure, with animal cells housing bacteria housing viruses is wonderful and fascinating, pointing to a rich diversity of interspecies <a href="http://scienceblogs.com/oscillator/2010/01/cooperation_and_experimental_e.php">cooperation</a> in nature.</p> <p>There's still a lot that we don't know about carboxysomes, and there's a lot of active research going on in my lab about how carboxysomes are formed and controlled inside of photosynthetic cells, with the goal of being able to engineer special protein substructures inside any bacterial cell. Stay tuned for more on that shortly!</p> </div> <span><a title="View user profile." href="/author/cagapakis" lang="" about="/author/cagapakis" typeof="schema:Person" property="schema:name" datatype="">cagapakis</a></span> <span>Wed, 03/10/2010 - 02:07</span> <div class="field field--name-field-blog-tags field--type-entity-reference field--label-inline"> <div class="field--label">Tags</div> <div class="field--items"> <div class="field--item"><a href="/tag/bacteria" hreflang="en">bacteria</a></div> <div class="field--item"><a href="/tag/cooperation" hreflang="en">Cooperation</a></div> <div class="field--item"><a href="/tag/evolution" hreflang="en">evolution</a></div> <div class="field--item"><a href="/tag/photosynthesis" hreflang="en">photosynthesis</a></div> <div class="field--item"><a href="/tag/symbiosis" hreflang="en">symbiosis</a></div> <div class="field--item"><a href="/tag/viruses" hreflang="en">viruses</a></div> <div class="field--item"><a href="/tag/carbon-fixation" hreflang="en">carbon fixation</a></div> <div class="field--item"><a href="/tag/carboxysome" hreflang="en">carboxysome</a></div> <div class="field--item"><a href="/tag/organelle" hreflang="en">organelle</a></div> </div> </div> <div class="field field--name-field-blog-categories field--type-entity-reference field--label-inline"> <div class="field--label">Categories</div> <div class="field--items"> <div class="field--item"><a href="/channel/life-sciences" hreflang="en">Life Sciences</a></div> </div> </div> <section> <article data-comment-user-id="0" id="comment-2493506" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268215941"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Also there are membrane-bound organelles in bacteria, e.g., magnetosomes.<br /> These protein-shell ones are also cool.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493506&amp;1=default&amp;2=en&amp;3=" token="3xfi1LUTiReL_73CzYTU9rRSVL_Y5VlmRvsf-Q69uNo"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Joe (not verified)</span> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493506">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="307" id="comment-2493507" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268224868"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Oh yeah! There's someone in my lab working on magnetosomes too (it's a big lab)! Maybe something for another future blog post :)</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493507&amp;1=default&amp;2=en&amp;3=" token="Bx6ESl2nmKopZo6lQGizw0s3OexAOzNYCqgvQ2LQfRU"></drupal-render-placeholder> </div> <footer> <em>By <a title="View user profile." href="/author/cagapakis" lang="" about="/author/cagapakis" typeof="schema:Person" property="schema:name" datatype="">cagapakis</a> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493507">#permalink</a></em> <article typeof="schema:Person" about="/author/cagapakis"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/author/cagapakis" hreflang="en"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493508" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268231587"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p><em>all the cell's enzymes and genetic material are instead floating freely in the cell.</em></p> <p>They're not separated into membrane-bound organelles (in general), but that doesn't mean that they're "floating freely". You have invaginations with proteins trapped in those regions for starters; but even more generally, everything in cytoplasm is packed tightly -- and trapped by its interactions with other proteins, and the dimensionality of its co-operative proteins (1, 2, or 3).</p> <p>It's very, very organized -- not "floating freely", just not as clearly divided as in eukaryotes. There's a big world between membrane-bound organelles and primitive bags of cytoplasm which supposedly existed 4 billion years ago.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493508&amp;1=default&amp;2=en&amp;3=" token="ku8FqhSYJ1xxC-Ai7RBCZLkvMpKq2j_dI-DY_5e8_-s"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">frog (not verified)</span> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493508">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493509" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268231754"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Great teaser at the end, leaving us to wonder what kind of awesome hacks are possible by employing these carboxysomes for our wishes ;).<br /> I'm still struggling with something though: if oxygen cannot fit through the cracks, how would the carbon dioxide (which is bigger) get in? The structure of the monomers seem to be too simple for elaborate mechanisms like the <a href="http://en.wikipedia.org/wiki/Potassium_channel#Selectivity_filter">selectivity filters</a> in ion channels.. Are funky nano-physics to blame?</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493509&amp;1=default&amp;2=en&amp;3=" token="Zq5RO_rNg6XRY8czBJqZqwZiCsBSO5xTNEsC66ZELmY"></drupal-render-placeholder> </div> <footer> <em>By <a rel="nofollow" href="http://www.lucasbrouwers" lang="" typeof="schema:Person" property="schema:name" datatype="">Lucas (not verified)</a> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493509">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493510" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268232328"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p><em>all the cell's enzymes and genetic material are instead floating freely in the cell.</em></p> <p>They're not separated into membrane-bound organelles (in general), but that doesn't mean that they're "floating freely". You have invaginations with proteins trapped in those regions for starters; but even more generally, everything in cytoplasm is packed tightly -- and trapped by its interactions with other proteins, and the dimensionality of its co-operative proteins (1, 2, or 3).</p> <p>It's very, very organized -- not "floating freely", just not as clearly divided as in eukaryotes. There's a big world between membrane-bound organelles and primitive bags of cytoplasm which supposedly existed 4 billion years ago.</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493510&amp;1=default&amp;2=en&amp;3=" token="QCbFpwwbvf-qhF1BZRgBYqGwpFM5hZ0ZhnsQ3nuHIrw"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">frog (not verified)</span> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493510">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493511" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268232820"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>@frog you're right, it's definitely an oversimplification to go from "no organelles" to "freely floating." Not to give it away but some of the caeboxysome work in my lab is about how they are spatially regulated by the cytoskeleton, and this kind of control happens even without carboxysomes. </p> <p>@Lucas I'm afraid I oversplifies this part too, it's less that oxygen can't get in and more that you're hugely concentrating carbon dioxide because the carboxysomes also associate with carbonic anhydrase. </p> <p>I was having a hard time figuring out how much detail I needed to include in this post, seems like I underestimated! Thanks for pointing out these important issues!</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493511&amp;1=default&amp;2=en&amp;3=" token="KjMskn9sByuammEdB6a3x92NM_Wb9oZshXkXzLMrzpI"></drupal-render-placeholder> </div> <footer> <em>By <span lang="" typeof="schema:Person" property="schema:name" datatype="">Christina (not verified)</span> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493511">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> <article data-comment-user-id="0" id="comment-2493512" class="js-comment comment-wrapper clearfix"> <mark class="hidden" data-comment-timestamp="1268273171"></mark> <div class="well"> <strong></strong> <div class="field field--name-comment-body field--type-text-long field--label-hidden field--item"><p>Thanks for the explanation.<br /> The balance between simplicity and detail can be tricky, but I like that the post is so accessible. It gave me a chance to think for myself and ask questions!</p> </div> <drupal-render-placeholder callback="comment.lazy_builders:renderLinks" arguments="0=2493512&amp;1=default&amp;2=en&amp;3=" token="QzcpgkEs1NMSj6zR_L8kZgxq8ma_EW3u90KHGHKtOgk"></drupal-render-placeholder> </div> <footer> <em>By <a rel="nofollow" href="http://www.lucasbrouwers.nl" lang="" typeof="schema:Person" property="schema:name" datatype="">Lucas (not verified)</a> on 10 Mar 2010 <a href="https://scienceblogs.com/taxonomy/term/36017/feed#comment-2493512">#permalink</a></em> <article typeof="schema:Person" about="/user/0"> <div class="field field--name-user-picture field--type-image field--label-hidden field--item"> <a href="/user/0" hreflang="und"><img src="/files/styles/thumbnail/public/default_images/icon-user.png?itok=yQw_eG_q" width="100" height="100" alt="User Image" typeof="foaf:Image" class="img-responsive" /> </a> </div> </article> </footer> </article> </section> <ul class="links inline list-inline"><li class="comment-forbidden"><a href="/user/login?destination=/oscillator/2010/03/10/bacterial-organelles%23comment-form">Log in</a> to post comments</li></ul> Wed, 10 Mar 2010 07:07:12 +0000 cagapakis 146860 at https://scienceblogs.com