elektrontransportkeðjuna

The electron transport chain, or elektrontransportkeðjan in Danish, is a critical process in cellular respiration that generates most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. This chain is located in the inner mitochondrial membrane in eukaryotes and the plasma membrane in prokaryotes. It consists of a series of protein complexes and small organic molecules.

Electrons are passed sequentially from one molecule to the next in a series of redox reactions. These electrons originate 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 move down the chain, energy is released. This energy is used by the protein complexes to pump protons (H+ ions) from the mitochondrial matrix to the intermembrane space. This pumping action creates an electrochemical gradient across the inner mitochondrial membrane.

The potential energy stored in this proton gradient is then utilized by a separate enzyme complex called ATP synthase. Protons flow back across the membrane through ATP synthase, driving the synthesis of ATP from ADP and inorganic phosphate. This process is known as chemiosmosis. The final electron acceptor in the chain is typically oxygen, which combines with protons to form water. The electron transport chain is thus essential for aerobic respiration and the efficient production of energy in most living organisms.