Difference between Cyclic and Non-cyclic Photophosphorylation

The upcoming discussion will update you about the differences between Cyclic Photophosphorylation and Non-cyclic Photophosphorylation.

Difference # Cyclic Photophosphorylation:

1. It is performed by photosystem I independently.

2. An external source of electrons is not required because the same electrons get revelled.

3. It is not connected with photolysis of water. Therefore, no oxygen is evolved.

4. It synthesizes only ATP.

5. It operates under low light intensity, anae­robic conditions or when CO₂ availability is poor.

6. The system does not take part in photosynthesis except in certain bacteria.

7. It occurs mostly in stromal or interregnal thylakoids.

8. ATP synthesis is not affected by DCMU.

Difference # Non-Cyclic Photophosphorylation:

1. It is performed by collaboration of both photosystems II and I.

2. The process requires an external electron donor.

3. It is connected with photolysis of water and liberation of oxygen.

4. Noncyclic photophosphorylation is not only connected with ATP synthesis but also production of NADPH.

5. Noncyclic photophosphorylation takes place under optimum light, aerobic conditions and in the presence of carbon dioxide.

6. The system is connected with CO₂ fixation in all plants.

7. It occurs in the granal thylakoids.

8. DCMU inhibits noncyclic photophos­phorylation.