Non-cyclic photophosphorylation

• 1. Light is absorbed by the chlorophyll in both photosystems and excited electrons are emitted from the primary pigment of both reaction centres.
• 2. The primary pigment of photosystem II receives replacement electrons from the photolysis of water.
• 3. The primary pigment of photosystem I receives electrons from photosystem II.
• 4. As the electron passes from photosystem II to photosystem I it passes along a chain of carriers, the electron transport chain. The energy of the electron is released and used to pump protons across the thylakoid membrane. The hydrogen ions accumulate in the thylakoid space
• 5. The protons passes back across the membrane through ATP synthase from the thylakoid space back into the stroma. This provides kinetic energy that allows the ATP synthase to produce ATP from ADP and inorganic phosphate.
• 6. The electron is then accepted by NADP after leaving photosystem I.
• 7. The end products of non-cyclic photophosphorylation are ATP and reduced NADP.