elektrontransportketi

The electron transport chain, or elektrontransportkjeden in Norwegian, is a series of protein complexes and electron carrier molecules embedded in the inner mitochondrial membrane in eukaryotes. This process is a crucial part of cellular respiration, the metabolic pathway that converts biochemical energy from nutrients into adenosine triphosphate (ATP), and subsequently releases waste products. The electron transport chain itself does not produce ATP directly but rather creates a proton gradient across the inner mitochondrial membrane.

Electrons are passed from one carrier molecule to the next in a series of redox reactions. These electrons originate from electron carriers like NADH and FADH2, which are generated during earlier stages of cellular respiration, such as glycolysis and the citric acid cycle. As electrons move through the chain, energy is released, which is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space. This establishes an electrochemical gradient, with a higher concentration of protons in the intermembrane space.

This proton gradient represents a form of stored potential energy. Protons then flow back into the mitochondrial matrix down their concentration gradient through a specialized enzyme called ATP synthase. This flow of protons drives the synthesis of ATP from ADP and inorganic phosphate, a process known as oxidative phosphorylation. The final electron acceptor in the chain is oxygen, which combines with electrons and protons to form water.