Electron Transport Chains
Electron transfer is the elemental transaction in chemical reactions. An atom donates an electron to another atom in a process that takes a few quadrillionths (10-15) of a second.
An electron transport chain comprises electron transfer between a series of electron donors and acceptors. Electron transport chains are formed by protein complexes embedded in a membrane that act concertedly during a sequence of redox reactions.
A complex is reduced by accepting electrons. Conversely, a complex is oxidized when it gives up electrons.
An electron transport chain works because each acceptor, the next in the chain, is more electronegative than the donor. For an electron transport chain to function – allowing electrons to pass through – an exogenous electron acceptor must be present at the end of the chain.
Some protein complexes use electron transport chains to transfer H+ ions (protons) across a membrane. This is part of the oxidative phosphorylation process, which is a metabolic pathway to use energy released by the oxidation of nutrients to produce ATP.
