Chemiosmosis and ATP production

During aerobic respiration, electron transport in mitochondria helps build a proton gradient across the inner membrane. Protons returning through ATP synthase provide energy for ATP production. Oxygen serves as the final electron acceptor in this transport chain. If the membrane becomes freely permeable to protons, the gradient weakens. Electron transport may continue, but ATP production through ATP synthase falls because the stored gradient is lost. This separates the roles of electron transfer and the proton gradient.