Coupling and respiratory control:

Electron transport is generally tightly coupled to ATP synthesis instance example for that is electrons do not flow by the electron transport chain to oxygen unless ADP is concurrently phosphorylated to ATP. Clearly, it also follows which ATP is not synthesized unless electron transport is occurring to give the proton gradient. Therefore oxidative phosphorylation required FADH₂ or NADH, oxygen, ADP and inorganic phosphate. The real rate of oxidative phosphorylation is set through the availability of ADP if ADP is added to mitochondria and the rate of oxygen consumption rises as electrons flow down the chain and then the rate of oxygen utilization falls when all the ADP has been phosphorylated to ATP; a procedure known as respiratory control. This mechanism ensures in which electrons flow down the chain only when ATP synthesis is required. If the level of ATP is high and the ADP level is low, no electron transport occurs, FADH₂ and NADH build up, as does excess citrate and the citric acid cycle and glycolysis are inhibited.