Differences between Pigment System I and Pigment System II
| Pigment System I (PS I) | Pigment System II (PS II) |
| PS I is made up of about 200 to 400 chlorophyll molecules;
50 carotenoid molecules; one molecule of reaction centre P700 (Chl.a700), Plastocyanin, Cytochrome f each; two molecules of Cyt. b563 (Cyt b6) and one or 2 molecules of ferredoxin. | PS II is made up of about 200 chlorophyll molecules;
50 carotenoid molecules; one molecule of reaction centre P680 (Chl. a680), and other substances Z, Mn++, Cl-, Quinone, Cytochrome b6 (b559), Cytochrome f and Plastocyanin each. |
| 2. Usually the number of Chl. b. molecules is less. | 2. Usually the number of Chl. b molecules is more. |
| 3. It’s reaction centre is P700 | 3. Its reaction centre is P680. |
| 4. It is located on the outer surface of the thylakoid. | 4. It is located on the inner surface of the thylakoid. |
| 5. In this system, molecular O2 is not evolved. | 5. In this system, molecular O2 is evolved as a result of the breakdown of water. |
| 6. Pigment System I formed NADPH + H+. | 6. NADPH + H+ is not formed in PS II. |
| 7. It participates in both cyclic and non-cyclic photophosphorylation. | 7. It participates only in non-cyclic photophosphorylation. It gives elections to PS I when NADP is reduced to. NADPH + H+ in PS I. |
| 8. When chloroplasts are ultracentrifuged, PS I being lighter comes up. Thus, PS IBcomes under a lighter fraction. | 8. On ultracentrifugation, PS II being heavier settles down. Thus PS II comes under a heavier fraction. |