What is the Electron Transport Chain (ETC)?

The electron transport chain is a process that occurs in the inner membrane of mitochondria. It involves the transport of electrons through 4 complexes in the membrane, which provides energy for the transfer of H⁺ ions (coming from reduced NAD and reduced FAD made in aerobic respiration) into the intermembranous space. These H⁺ ions then diffuse down the electrochemical membrane back into the mitochondrial matrix through ATP Synthase, which uses this movement to drive ATP synthesis. Oxygen is the final electron acceptor, removing electrons and H⁺ ions so that the ETC may start again. Overall, 32 ATP molecules are generated, and for every two electrons and two H⁺ ions a molecule of water is made using half an O₂ molecule.