Photsynthesis IV

1. For every two photons ( one photon per P.S. ) one electron is transferred from H2O to NADP+.
2. For one O2 molecule transfer of 4 e are required, i.e. 8 photons ( 4 photons per P.S. )
3. Binding of PQA to protein is the site for action of many commercial herbicides like DCMU.

Cytb6f links PSII and PSI

Cytb6f is similar to Complex III of mitochondria.

Chloroplast Mitochondria

A. Cytb6f Cytbc1
B. PQB QB
C. PC Cyt c
D. Proton transfer ( outside ---inside) Proton transfer ( inside ----outside )