Final Electron Acceptor

∞ generated and posted on 2016.12.05 ∞

That substance which receives the terminal waste product of cellular respiration.

In Final Electron Acceptor, 'Final' means 'last', as in last electron acceptor, 'Electron' is the subatomic particle that is being moved from compound to compound, and 'Acceptor' means literally to accept, that is, to acquire the electron. Final Electron Acceptor thus is the final thing (compound) to accept an electron, particularly at the point where the organism or at least biochemical pathway is now done (finished) with the electron.

The most common of final electron acceptors is molecular oxygen, O2, which combines with the spent electrons of cellular respiration, along with protons, to generate what is known as metabolic water. We breathe in to supply the oxygen necessary to keep cellular respiration going. Without oxygen the electrons in the electron transport chain have nowhere to go, so it backs up the system, shutting down the "aerobic" means of generating ATP.

There in addition exists a whole diversity of electron acceptors that are used in what is known as anaerobic respiration. Anaerobic respiration is used by numerous bacterial types, particularly prokaryotes that can be referred to as chemolithotrophs or "rock eaters". These non-oxygen final electron acceptors generally require higher energy electrons than oxygen, resulting in less energy extraction (proton pumping) than can be achieved by anaerobic electron transport chains.