Identifying a Smallish Frog

[Alyrium Denryle]

^ These aren't "our" cells yet, really. Somewhere along the line, proto-eukaryotes absorbed primitive aerobic bacteria, and that's why our cells today have mitochondria.

Look up anaerobic bacteria, there are tons of other ways to fuel metabolism. I believe H2S metabolism was very popular back then (and it's still very common today).

Well yeah, but I was not going to nitpick

[Bottlestein]

^ These aren't "our" cells yet, really. Somewhere along the line, proto-eukaryotes absorbed primitive aerobic bacteria, and that's why our cells today have mitochondria.

Look up anaerobic bacteria, there are tons of other ways to fuel metabolism. I believe H2S metabolism was very popular back then (and it's still very common today).

That's pretty cool - I had no idea that acid breakdown released enough energy to manufacture the enzymes necessary to function. Were the ribosomes in these bacteria very different from "our" (I guess eukaryotic) ribosomes - or the same two subunit structure? Also, how long did the explosion of facultative anaerobes take from the time that oxygen became a significant percent of the atmosphere? What I'm trying to ask is, were there many aerotolerant bacteria whose enzymes, membrane proteins, etc were better off in the oxygenated atmosphere, or were there very few common ancestors to the aerobic species?

[Anguirus]

I think ribosomes are very highly conserved.

As for the rest of your questions, you'd do just as well to look them up...I'm not an expert on the history of life.