Protons travel along a concentration gradient, passing through the ATP synthase which converts rotational kinetic energy into chemical energy stored in ATP

Protons are pumped against a concentration gradient using the energy derived from the electrons travelling along the chain.

The electrons that travel through the electron transport chain end up reducing oxygen to produce water.

Coenzyme Q and Cytochrome C are responsible for the harvesting of protons from NADH and FADH2