Describe the process of oxidative phosphorylation

There are four main electron carrier protein complexes in the inner mitochondrial complex, which use the energy from the transfer of electrons to pump H+ into the intermembrane space, this is known as the electron transport chain. H+ and e- are generated from the breakdown (re-oxidisation) of NADH and FADH2 (at Complexes I and II respectively) and are produced by the Krebs cycle. The H+ build up in the intermembrane space creates a proton gradient which causes the H+ ions to diffuse through a protein channel associated with ATP synthase which uses the gradient's energy to facilitate the formation of ATP from ADP + Pi. The electrons left over from the transport chain react with oxygen, as the terminal reaction of the electron transport chain and create oxygen radicals. These oxygen radicals react with the H+ ions in the mitochondrial matrix to produce water.