hengitysketju

Hengitysketju, also known as the electron transport chain, is a critical process in cellular respiration that generates a large portion of ATP, the energy currency of cells. It is the final stage of aerobic respiration and occurs within the inner mitochondrial membrane in eukaryotic cells.

The process begins with the transfer of electrons from electron carriers, NADH and FADH2, which were produced during earlier stages like glycolysis and the Krebs cycle. These electrons are passed down a series of protein complexes embedded in the mitochondrial membrane. As electrons move through these complexes, they release energy.

This released energy is used to pump protons (H+) from the mitochondrial matrix into the intermembrane space, creating a proton gradient across the inner membrane. This gradient represents stored potential energy.

Finally, protons flow back into the mitochondrial matrix through an enzyme called ATP synthase. This flow of protons drives ATP synthase to catalyze the synthesis of ATP from ADP and inorganic phosphate. Oxygen acts as the final electron acceptor in the chain, combining with electrons and protons to form water. Without oxygen, the electron transport chain and thus significant ATP production would cease.