Write notes on photosystem I and II.
Photosystem I [PSI] :
Location : It is present in the membrane of stroma thylakoids and non-appressed parts of grana thylakoids.
Pigment molecules : In PS I the reaction centre chlorophyll a which has an absorption peak at P700.
Reducing agents : The PS I has following reducing agents viz. ferrodoxin, plastoquinone, cytochrome complex, n-plastocyanin.
Function of PS I : In PS I cyclic photophos-phorylation occurs.
Photosystem II [PS II] :
Location : It is present in appressed part of grana thylakoids.
Pigment molecules : It has in the centre special type of chlorophyll ‘a’ molecules called P680.
Reducing agents : PS II has quencher, plastoquinone, cytochrome complex and plastocyanin reducing agents.
Function : In PS II non-cyclic photophosphorylation occurs, alongwith photolysis of water.
