electron transport system
An electron transport system, also known as an electron transport chain, is a sequence of biochemical reactions that transfers electrons, through a series of carriers, in certain metabolic processes (see metabolism). It involves carrier substances that accept electrons and then donate them to the next carrier in the chain, while themselves undergoing a series of redox reactions. It forms the last stage of aerobic respiration in cells, causing hydrogen atoms to combine with oxygen to form water and conserving energy in the form of ATP. Photosynthesis also involves an electron transport system.