1. The synthesis of ATP that takes place during photosynthesis. In noncyclic photophosphorylation the photolysis of water produces electrons that generate a proton motive force which is used to produce ATP, the electrons finally being used to reduce NADP to NADPH.
When the cellular ratio of reduced to nonreduced NADP is high, cyclic photophosphorylation occurs and the electrons pass down an electron transport system and generate additional ATP, but no NADPH.
(31 Dec 1997)
