Electron Transport Chain

[Avicenna]

Is the hydrogen ion that reduces the oxygen to form water different than the hydrogen ion that gets pumped into the intermembrane space of the mitochondria for chemiosmosis? Or are they one and the same?

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[FauxBlue]

I believe they are different. How I see it is that the odds of the SAME hydrogen ion pumped into the intermembrane space, coming back through ATP synthase and to reduce the terminal electron acceptor (O2) is very unlikely. (Please correct me if I am wrong)

 

[Parcas]

They are essentially the same hydrogen (maybe not literally the exact same H molecule, but they're primarily coming from NADH and FADH2). The hydrogens that are in the intermembrane space are the result of the oxidation of NADH and FADH2. Their hydrogens then travel through the electron transport chain via specialized channels until an electrochemical gradient of H+ is formed, which allows those hydrogens to then pass through the ATP Synthase (which will then reduce oxygen to form water). Unless there is hydrogen leakage somewhere (which could happen), the hydrogens are technically the same hydrogens as from chemiosmosis (they just need to go through the ETC). Not sure if that answers your question, but I hope it helps!

Maybe watch this video to help your understanding of cellular respiration.