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− The oxidized reaction centre of the chlorophyll, that had donated
an electron, is reduced by a secondary donor, which in turn is reduced by a tertiary
donor.
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− The water (H2O) is oxidized by light (photolysis) to oxygen. The
oxidation of water as the primary source of electrons. Protons also are released in the
lumen by PS-II.
− The primary electron and proton are transferred from chlorophyll
of the PS-II to chlorophyll of the PS-I that had donated the electron. This is called
non-cyclic electron transfer.
− The electron in PS-I is transferred through electron protein
carriers, and return to PS-I again. This is called cyclic electron transfer.
from the lumen to stroma.
− Then, ATP is released into the stroma by proton (H + ) moving
− In plant, water (H2O) is the ultimate electron donor, and NADP +
is the ultimate electron acceptor.Moving electrons, electron flow, to synthesize ATP is
called Z scheme.
− PS-II oxidizes water, while PS-I reduces NADP + .
− NADP + is reduced to NADPH on the stromal side of the
membrane via the action of ferredoxin (Fd) and the flavoprotein ferredoxin-NADP
reductase (FP).
− All the electron carriers are known to function in electron flow
from water (H2O) to NADP + .
complex.
− PS-II produces an oxidant that can oxidize the cytochrom b6f
− The transfer of electrons (e-) and protons (H+) in thylakoid
membrane is carried out by protein complexes--PS-II, the cytochrom b6f, PS-I, and
the ATP synthease.