Endosymbiosis

hoggy87

I understand the theory that Mitochondria were originally prokaryotic cells.
But what I don't understand is how they can be passed on from generation to generation in eukaryotes? It's obviously not Lamarckian evolution, but I've never seen any information which clears my misunderstanding up.

DrIndy

Mitochondria are passed on maternally in the ova. As with any natural evolution, if it is of benefit to the organism, then it is facilitated in passing this trait or organelle on.

hoggy87

DrIndy wrote:

Mitochondria are passed on maternally in the ova. As with any natural evolution, if it is of benefit to the organism, then it is facilitated in passing this trait or organelle on.

But surely there are genes that code for the production of mitochondria? A mitochondrial like prokaryote happened to worm its way into an ovum, and got copied, when the zygote formed, via mitosis? Am I on the right track? I do apologise for my stupidity. I do usually have a good enough grasp of the concepts of Darwinian Natural Selection!

Kevster

The exact same theory is applied to plant Chloroplasts. Not only have Mitochondria and Chloroplasts their own DNA, it is DNA that is remarkably similar in structure to bacterial DNA. Also, the membranes on these organelles are made-up of amino acids that are only found in bacterial membranes. The metabolism in Mitochondria is also similar to that of many bacteria and the way that Chloroplasts photosynthesise is performed in exactly the same way as the Cyanobacteria photosynthesise. The evidence for endosymbiosis is very strong.


Bacteria are the true conquerers of this world. When mammals (including us), fish, and all other animals have vanished the only life that will remain will be the glorious Prokaryotes: The Eubacteria and Archaebacteria.

hoggy87

Kevster wrote:

The exact same theory is applied to plant Chloroplasts. Not only have Mitochondria and Chloroplasts their own DNA, it is DNA that is remarkably similar in structure to bacterial DNA. Also, the membranes on these organelles are made-up of amino acids that are only found in bacterial membranes. The metabolism in Mitochondria is also similar to that of many bacteria and the way that Chloroplasts photosynthesise is performed in exactly the same way as the Cyanobacteria photosynthesise. The evidence for endosymbiosis is very strong.


Bacteria are the true conquerers of this world. When mammals (including us), fish, and all other animals have vanished the only life that will remain will be the glorious Prokaryotes: The Eubacteria and Archaebacteria.

Don't get me wrong, I'm a second year Biochem student, and there's not a doubt in my mind that this is the case. It's just the exact mechanism for the original "colonisation" of mitochondria/chloroplasts into eukaryote cells and their subsequent vertical transmission down through the generations is what I was asking about. Apologies if this was unclear.

Kevster

Ah! Cool - I'm a second-year Applied Biology student. The theory is amazing isn't it? The way that they integrated with Eukaryotes is something that puzzles me too. I cannot possibly understand how it could be done at this moment in time but I'm sure that I will develop my own theories for it in the future.

Do you have any ideas yourself?


Kevin.