Yes, in the vast majority of complex lifeforms, oxygen absolutely serves as the final electron acceptor during cellular respiration. To understand why this is such a critical biological milestone, we have to trace the journey of electrons through the Electron Transport Chain (ETC) and see how oxygen’s unique chemical properties make it the ideal partner for life-sustaining energy production.
Introduction
Cellular respiration is the metabolic process by which cells convert nutrients into energy. At the heart of this process lies the transfer of electrons through a series of protein complexes embedded in the inner mitochondrial membrane. These electrons are carried by electron carriers—primarily NADH and FADH2—which donate their electrons to the beginning of the transport chain. As these electrons move down the chain, they lose potential energy, which is used to pump hydrogen ions across the membrane. This establishes an electrochemical gradient that ultimately drives the production of ATP, the energy currency of the cell. The molecule at the end of this chain that claims the final electron is oxygen. Without oxygen acting as this terminal acceptor, the entire electron transport
