Non-cyclic photophosphorylation:
a. It involves both photosystems- PS-I and PS-II.
b. In this case, electron transport chain starts with the release of electrons from PS-II.
c. In this chain high energy electrons released from PS-II do not return to PS-II but, after passing through an electron transport chain, reach PS-I, which in turn donates it to reduce NADP to NADPH.
d. The reduced NADP+ (NADPH) is utilized for the reduction of CO2 in the dark reaction.
e. Electron-deficient PS-II brings about oxidation of watermolecule. Due to this, protons, electrons and oxygen atom are released.
f. Electrons are taken up by PS-II itself to return to reduced state, protons are accepted by NADP+ whereas oxygen is released.
g. As in this process, high energy electrons released from PSII do not return to PS-II and it is accompanied with ATP formation, this is called Non-cyclic photophosphorylation.
