Energy for the synthesis of ATP can become available in two ways:
- In aerobic respiration, energy is released by reorganising chemical bonds during Glycolysis and the Krebs Cycle.
- Harnessing the energy given off by H+ ions as electrical potential energy, in Oxidative Phosphorylation.
N.B. The carrier protein which spans the phospholipid bilayer of the mitochondrion has incorporated into it the enzyme ATP synthase. This enzyme has three binding site, which rotate as H+ ions pass. The rotation leads to structural changes in the biding sites, and allows them to synthesize ATP in three stages:
- Binding P to ADP
- Formation of ATP
- Release of ATP