At the end of the Krebs Cycle, most of the energy extracted from glucose is in molecules of NADH and FADH 2 . These reduced coenzymes link glycolysis and the Krebs Cycle to oxidative phosphorylation by passing their electrons down the electron transport chain to oxygen. This exergonic transfer of electrons down the ETC to oxygen is coupled to ATP synthesis. The electron transport chain is made of electron carrier molecules embedded in the inner mitochondrial membrane. Each successive carrier in the chain has a higher electronegativity than the carrier before it, so the electrons are pulled downhill towards oxygen, the final electron acceptor and the molecule with the highest electronegativity.
Prosthetic groups alternate between reduced and oxidized states as they accept and donate electrons.
Prosthetic group composed of four organic rings surrounding a single iron atom. Type of protein molecule that contains a heme prosthetic group and that functions as an electron carrier in the electron transport chains of mitochondria and chloroplasts. There are several cytochromes, each a slightly different protein with a heme group. It is the iron of cytochromes that transfers electrons.