What occurs in the electron transport chain in cellular respiration?

In the electron transport chain, a crucial process of cellular respiration, ATP is synthesized from ADP. This occurs through a series of protein complexes located in the inner mitochondrial membrane. As electrons are transferred through these complexes, derived from the oxidation of NADH and FADH2 (which are produced in earlier stages of cellular respiration like glycolysis and the citric acid cycle), they release energy.

This energy is utilized to pump protons (H+) from the mitochondrial matrix into the intermembrane space, creating a proton gradient. This gradient is then harnessed by ATP synthase, an enzyme that allows protons to flow back into the matrix. As protons move through ATP synthase, it catalyzes the conversion of ADP and inorganic phosphate (Pi) into ATP. This process exemplifies oxidative phosphorylation and is the primary method of ATP production within aerobic organisms.

The production of ATP in the electron transport chain is vital, as it provides the energy necessary for various cellular processes. The role of oxygen in this stage is as the final electron acceptor, forming water, but the primary function highlighted here is the synthesis of ATP from ADP.