Why does most ATP come from the mitochondrial inner membrane rather than earlier breakdown steps?

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5
Joined:
01/21/2026

Yeah, that always tripped me up too until I dug a bit deeper. Basically, the early stages like glycolysis and the Krebs cycle only squeeze out a handful of ATP directly—think net 2 from glycolysis and maybe another couple from the cycle per glucose. But then those carrier molecules (NADH and FADH2) carry a ton of potential energy in their electrons. The real payoff hits when those electrons get shuffled through the electron transport chain right on the inner mitochondrial membrane. That process pumps protons out, building this gradient, and then they rush back through ATP synthase to crank out way more ATP—like 30-ish total from the whole thing. It's just way more efficient harnessing that stepwise electron drop and proton flow instead of direct chemical grabs earlier on. I actually sketched out a cellular respiration chart once to visualize the yields per stage, and it clicked how lopsided it is toward the membrane part. Kinda wild how cells evolved to maximize that tiny space.




#1 02/04/2026 at 09:11 PM
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