Chemiosmosis

Chemiosmosis is the mechanism by which cells generate the majority of their chemical energy, using the movement of ions, typically protons, across a membrane down an electrochemical gradient to drive the synthesis of adenosine triphosphate. British biochemist Peter Mitchell proposed the chemiosmotic hypothesis in 1961, arguing that the electron transport chains of mitochondria and chloroplasts pump protons across a membrane to build up a gradient whose energy is then captured by the enzyme ATP synthase, a proposal that met considerable early resistance before being confirmed experimentally and earning Mitchell the 1978 Nobel Prize in Chemistry. Chemiosmosis is now understood as the central energy-conversion mechanism of cellular respiration and photosynthesis across nearly all forms of life.