citric acid cycle

[Eddy the Very Great]

I'm confused about the citric acid cycle. It couldn't have evolved at once becaue it would mean that all the enzymes evolved at the same time, but it couldn't have evolved in stages because that would be pointless until the whole thing is complete.

[Cyborg Stan]

I'm tired, and there's not enough here for a decent response. Read this instead, starting on the section titled The Krebs Cycle

Darwin's Black Box Irreducible Complexity or Irreproducible Irreducibility

Now, shall we start a discussion on the shortcomings of 'Intelligent Design' Theory?

[Trytostaydead]

I'm confused about the citric acid cycle. It couldn't have evolved at once becaue it would mean that all the enzymes evolved at the same time, but it couldn't have evolved in stages because that would be pointless until the whole thing is complete.

The best I can say is the TCA occurs in the mitochondria and there are those who propose the mitochondria was never really part of the body in the first place, a foreign body that somehow lives symbiotically with the body.

So, perhaps the TCA evolved as part of the original mitochondrial 'organism' that lived in a symbioism to take pyruvate from its host and deliver goods like ATP and stuff..

But you're right. The TCA is an amazingly complex system that requires many constant interactions between the mitochondria itself and the intracelleular environment, and seemingly the body 'evolved' to catbolize specific compounds to be delivered into the TCA (keto-acids, acetyl-coA, etc.)