öndunarkeðjunni

Öndunarkeðjunni, also known as the electron transport chain, is a vital metabolic pathway that occurs in the mitochondria of eukaryotic cells and the plasma membrane of prokaryotic cells. Its primary function is to generate ATP, the main energy currency of the cell, through a series of redox reactions. The process involves a sequence of protein complexes embedded within the inner mitochondrial membrane.

These protein complexes, designated as Complex I through Complex IV, accept electrons from electron carriers like NADH and FADH2, which are produced during earlier stages of cellular respiration, such as glycolysis and the Krebs cycle. As electrons are passed from one complex to the next, energy is released. This energy is then used to pump protons (H+) from the mitochondrial matrix into the intermembrane space, creating an electrochemical gradient.

Oxygen serves as the final electron acceptor in this chain, combining with electrons and protons to form water. This step is crucial for maintaining the flow of electrons through the chain. The proton gradient established across the inner mitochondrial membrane represents a form of potential energy. This energy is harnessed by another protein complex, ATP synthase, which allows protons to flow back into the matrix. The movement of protons through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate. This process is known as oxidative phosphorylation.