As promised here is an explanation of the how of the development of eukaryotic cells. As proposed by Martin and Muller the hydrogen hypothesis goes initially against logic by arguing that it is hydrogen that forced eukaryotes to develop and not oxygen (the bottle neck most commonly thought of as pushing for aerobic respiration and thus mitochondria). However the theory is broken down into very logical evolutionary steps that make a lot of sense.
The hypothesis starts with a methanogen (as discuses in previous posts) which thrives of carbon dioxide and hydrogen gas producing methane as its only form of energy. Now it is evident that the methanogen living in anaerobic conditions could not survive for too long in an oxygen rich environment, as oxygen would react with the hydrogen forming water, meaning the cell could not form glucose in its normal way. Now at the same time a bacterium is living in close proximity with the methanogen, benefiting the methanogen by releasing the carbon dioxide and hydrogen the methanogen loves. The bacterium has special genes to absorb glucose that the methanogen can only dream about at this point.
As the relationship between the methanogen and the bacterium is so beneficial to the methanogen, it is not surprising when the larger methanogen engulfs the bacterium and now becomes a part of the newly formed cell. Now this may appear to be irrelevant to how eukaryotes develop as we all know the modern mitochondria are aerobic and use oxygen. Additionally this seems strange because eukaryotes can also use phagocytosis to 'absorb' food stuff. The likeliest explanation of all is that some horizontal gene transfer occurred from bacterium to what now cant really be considered to be a methanogen, but eukaryote.
Now the eukaryote has all of the full sections of coding genes to absorb glucose, just as the bacterium once did. The mitochondria (most likely to have once been alpha-proteobacteria) produce energy much more efficiently than the methanogen ever did by it's self (mentioned in previous posts). this combined with the abundance of oxygen in the new world. The eukaryotic cell is born.
The hypothesis starts with a methanogen (as discuses in previous posts) which thrives of carbon dioxide and hydrogen gas producing methane as its only form of energy. Now it is evident that the methanogen living in anaerobic conditions could not survive for too long in an oxygen rich environment, as oxygen would react with the hydrogen forming water, meaning the cell could not form glucose in its normal way. Now at the same time a bacterium is living in close proximity with the methanogen, benefiting the methanogen by releasing the carbon dioxide and hydrogen the methanogen loves. The bacterium has special genes to absorb glucose that the methanogen can only dream about at this point.
As the relationship between the methanogen and the bacterium is so beneficial to the methanogen, it is not surprising when the larger methanogen engulfs the bacterium and now becomes a part of the newly formed cell. Now this may appear to be irrelevant to how eukaryotes develop as we all know the modern mitochondria are aerobic and use oxygen. Additionally this seems strange because eukaryotes can also use phagocytosis to 'absorb' food stuff. The likeliest explanation of all is that some horizontal gene transfer occurred from bacterium to what now cant really be considered to be a methanogen, but eukaryote.
Now the eukaryote has all of the full sections of coding genes to absorb glucose, just as the bacterium once did. The mitochondria (most likely to have once been alpha-proteobacteria) produce energy much more efficiently than the methanogen ever did by it's self (mentioned in previous posts). this combined with the abundance of oxygen in the new world. The eukaryotic cell is born.
1 comments:
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