As NADH and FADH approach, they are reduced and they donate their electrons, which then move down the membrane. H+ are pumped out and create a concentration gradient. H+ then diffuses down it's concentration gradient and ATP synthase uses the kinetic energy and converts it to chemical energy, thus producing ATP. Oxygen is a great oxidizing agent and acts as the final election acceptor (taking electrons), and producing H20 (which is later used in Krebs Cycle). Biochemistry Notes, Electron Transport Chain, Krebs Cycle, Chemical Energy, Kinetic Energy, Chemical Reactions, Anatomy And Physiology, Paradigm