Question

What is the difference between non cyclic photo phosphorylation and Z scheme?

Answer 1

Noncyclic photophosphorylation is the synthesis of ATP from ADP using energy from sunlight and involve two types of photosystems. Photophosphorylation takes place through energy transfer from sunlight to electrons and involve several oxidation- reduction reactions in the electron transport chain.
Z scheme is the representation of change in reduction potential of molecular species and electrons during noncyclic photophosphorylation. In Z scheme, electrons are removed from water by photolysis and get excited. These electrons move to the photosystem II. Photons from light excite the photosystem II species increasing their reduction potential. The excited photosystem II donates its electron to cyt-bf electron transport chain which in turn donate the electrons to photosystem I. The excited photosystem I, which has high reduction potential donate electrons to NADP through electron transport chain. Thus, reduction potential of species in the noncyclic photophosphorylation follow a Z scheme i.e. first increases then decreases again increases and then finally decreases.