Differences between Cyclic and Non-cyclic photophosphorylation :

S.No. Cyclic photophosphorylation                              Non-cyclic Photophosphorylation

1. Associated with PS I                                                     Associated with both PS I and PSII

2. Electron expelled from chl molecule                            Electron expelled from chl molecule

is cycled back.                                                                   is not cycled back. Its loss is compensated

                                                                                       by electrons coming from the photolysis of water.

3. Photolysis of water and O2                                         Photolysis of water and O2 evolution

evaluation does not take place                                        take place.

4. Phosphorylation takes place at two places                Phosphorylation takes place only at one place.

5. Two ATP molecules are produced.                             one ATP and one NADPH2 are produced.

6. NADP is not reduced                                                 NADP is reduced to NADPH2 and used in

                                                                                       assimilation of CO2.

7. This system is found dominantly in                           This is dominant in green plants

photosynthetic bacteria.

8. The process is not inhibited by DCMU/CMU        The process is stopped by the use of DCMU or                                                                                             CMU.





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