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Endosymbiosis and assimilation in genetic code

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Endosymbiosis and assimilation in genetic code

Postby Alek » Thu Sep 14, 2006 8:15 pm

After vigorously searching my textbook (Campbell/Reese) and the internet, I have been unable to find anything regarding how, exactly, RNA and DNA assimilation in symbionts (i.e mitochondria) occured. That is, how a cell assimilated this genetic information from other symbionts into itself. I would appreciate any help offered, as I have an exam tomorrow evening.

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Postby baikuza » Fri Sep 15, 2006 7:13 am

hmm... do you know how lichen arise on this world?
my master in highschool only said it happen by randomly... but i'm not satisfied already at the time.

oh well.. in this case of mitochondrion and chloroplast.. it happen because the ancient cell-procaryotic cell-, long time ago, egnulfed the bacterial cell. then they make relationship... and the time go pretty long and they said to be endosymbiotic.

the term of egnulfing the bacteria in this case said to be an endophagocytosis.

.. hmm. are you still not satisfied just like me?
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Postby MrMistery » Fri Sep 15, 2006 7:20 pm

good question. If you find the answer make you sure you tell me cause a lot of cytologists are being payed truckloads of money to find out how this happened. What we do know so far are:
1. It DID happen. Some genes in the nucleus that code for mithocondrial proteins resemble more bacterial proteins than cytosolic ones. For example, the gene that codes for mithocondrial superoxid dismutase in chickens resembles more the one found in bacteria than the one found in the cytoplasm of cicken cells.
2. It happened gradually. some organisms have mithocondrial genomes that code for a lot of proteins. The most evolved mithocondrial genomes have only a few tRNA, rRNA and electron transport chain coding genes. This means that some genes gradually moved from the mithocondrion to the nucleus. How?! In a complicated way. and as i said not yet understood. but what i can tell you is that this involves: acquiring posttranslational and splicing properties, mithocondrial targeting signaling sequences etc.

If you want something to do your PhD on, here's your topic.
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
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