The function of the electron transport chain and the synthesis
of ATP in the chlorophast
The electron transport chain
in chloroplast is a series of coupled oxidation reduction reactions. The
enzymes of the electron transport chain are located in the thylakoid membranes.
In noncyclic photophosphorylation,
the electron at the acceptor in PSII is transfered to the electron transport
The electrons are passed down
the electron transport chain and free energy is released. Some of the free
energy is used to translocate protons from the stroma into the intrathylakoid
space. The result being that the proton concentration in the intrathylakoid
space (pH 5) in much higher than in the stroma (pH 7).
There is a proton concentration
gradient across the thylkoid membrane. The protons travel down this gradient
through a protein complex called the ATP synthase. This enzyme uses the
energy released by the movement of protons down the gradient to convert
ADP and Pi into ATP.