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 chain


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.