Chemiosmosis

What is chemiosmosis?

Chemiosmosis is the synthesis of ATP driven by a proton (H⁺) gradient across a membrane. In photosynthesis, light energises electrons that pump H⁺ into the thylakoid lumen; the gradient drives ATP synthase. In respiration, the electron transport chain pumps H⁺ into the mitochondrial inter-membrane space; ATP synthase converts the flow-back into ATP. The principle (proposed by Peter Mitchell, 1978 Nobel Prize) is central to both energy-converting processes in cells.