Question

Define Non-cyclic photophosphorylation.

Answer 1

Photosynthesis is a two step process. In first step phosphorylation of ADP to ATP in the presence of sunlight take place (photophosphorylation) to produce large amount of energy (ATP) which is further used for second step of photosynthesis.Photophosphorylation is of two types cyclic and non-cyclic.In cyclic photophosphorylation Photon from the light excite an electron from the reaction center P680. This electron is than passed through ferredoxin to cytochrome b6f where phosphorylation of ADP to ATP take place and than it passes to the plastocyanin which return the electron to reaction center P680. In cyclic photophosphorylation electron comes back to the reaction center.In non-cyclic photophosphorylation electron does not come back to the reaction center P680 instead plastocyanin pass that electron to the reaction center P700 that uses that electron to convert NADP to NADPH.