elektrontranszferlánc

An elektrontranszferlánc, often translated as electron transport chain (ETC), is a series of protein complexes and electron carrier molecules embedded in the inner mitochondrial membrane in eukaryotes and the plasma membrane in prokaryotes. This crucial biological process is the final stage of cellular respiration and plays a pivotal role in ATP (adenosine triphosphate) production.

The ETC functions by accepting high-energy electrons from electron carriers like NADH and FADH2, which are produced during earlier stages of cellular respiration such as glycolysis and the Krebs cycle. These electrons are then passed sequentially from one complex to another. As electrons move down the chain, they release energy. This released energy is harnessed by the protein complexes to pump protons (H+ ions) from the mitochondrial matrix to the intermembrane space.

This proton pumping creates an electrochemical gradient across the inner mitochondrial membrane, with a higher concentration of protons in the intermembrane space than in the matrix. This gradient represents potential energy. The protons then flow back into the matrix through a specialized enzyme called ATP synthase. The energy from this proton flow drives the synthesis of ATP from ADP (adenosine diphosphate) and inorganic phosphate.

Oxygen serves as the final electron acceptor in the ETC of aerobic organisms. It combines with electrons and protons to form water. This continuous flow of electrons and the resultant proton gradient are essential for generating the vast majority of ATP required by cells for their metabolic activities. Disruptions to the elektrontranszferlánc can have severe consequences for cellular function and organismal health.