A sequence of biochemical reduction-oxidation reactions that affects the transfer of electrons through a series of carriers. Also known as the respiratory chain, forms the final stage of aerobic respiration.

Results in the transfer of electrons or hydrogen atoms derived from the Krebs cycle to molecular oxygen, with the formation of water. It conserves energy from food or light in the form of ATP.

Comprises a series of carrier molecules that undergo reversible reduction-oxidation reactions, accepting electrons and then donating them to the next carrier in the chain – a process known as electron flow. Also occurs in photosynthesis.