Cyclic and Non-Cyclic Photophosphorylation | Plants

The upcoming discussion will update you about the difference between cyclic photophosphorylation and non-cyclic photophosphorylation.

Difference # Cyclic Photophosphorylation:

1. It is found dominantly in bacteria.

2. It involves photosystem I only.

3. Electrons move in a closed circle. Electron expelled from chlorophyll (P₇₀₀) returns to it after passing through a series of electron accep­tors in an ETS.

4. It is not involved in the photolysis of water and therefore, no oxygen is involved.

5. It sythesises only ATP, reduced NADP, i.e., NADPH₂ is not synthesised.

6. It operates under low light intensity, anaerobic conditions and the poor availability of CO₂.

Difference # Non-Cyclic Photophosphorylation:

1. This is dominant in green plants.

2. It involves both photosystems I and II.

3. Electrons do not move in a closed circle. Here electron expelled by reaction centre (P₆₈₀) are not returned to them. Here water is the ultimate source of electrons and NADP⁺ is the final acceptor.

4. It is involved in the photolysis of water, and therefore oxygen is released as a by-product.

5. It is involved in the synthesis of both ATP and NADPH₂.

6. It takes place under optimum light, aerobic conditions and in the presence of sufficient CO₂.