Photosystem I (PS I) and Photosystem II (PS II) | Photosynthesis

The upcoming discussion will update you about the difference between Photosystem I (PS I) and Photosystem II (PS II).

Difference # Photosystem I (PS I):

1. Photosystem I (PS I) is involved in the cyclic and non-cyclic photophosphorylation.

2. Photosystem I (PS I) receives the electrons from photosystem II. This system produces a strong reductant which reduces NADP+ to NADPH₂.

3. Molecular oxygen is not evolved in this system.

4. PS I is located in the outer surface of the thylakoid, i.e., appressed regions of grana. 

5. The reaction centre of PS I is P₇₀₀.

6. Chlorophyll carotenoid pigments are in the ratio 20-30 : 1.

7. Chlorophyll a with maximum absorption at 700 nm(P₇₀₀).

Difference # Photosystem II (PS II):

1. Photosystem II (PS II) is involved only in non-cyclic photophosphorylation.

2. Photosystem II (PS II) donates electrons to photosystem I where NADP+ is reduced.

3. This system is responsible for the photolysis of water and involves the evolution of molecular oxygen.

4. PS II is located on the inner surface of the thylakoid, i.e., in the stroma and non-appressed regions of grana. 

5. The reaction centre of PS II is P₆₈₀.

6. Chlorophyll carotenoid pigments are in the ratio 3-7 : 1.

7. Chlorophyll a with peak absorption at 680 nm(P₆₈₀).