Q: Discuss the role of membranes in the synthesis of ATP during photosynthesis

The chloroplast is enclosed by two membranes, and this separates reactions within the chloroplast from the rest of the cytoplasm. The double membrane of the chloroplast also serves to maintain high substrate concentrations within the chloroplast for photosynthesis. The outer membrane of the chloroplast is smooth and is freely permeable to many substances. The inner membrane regulates the entry ot substances needed for photosynthesis, such as water. Floating in the stroma are tiny membrane sacs known as thylakoids. The thylakoid membranes are the site of the photosynthetic light reactions. Photosystems 1 and 2, are sequentially organized on the thylakoid membrane, responsible to trapping light energy for photosynthesis. Electron carriers are also organized on the thylakoid membrane. The flow of electrons down the electron transport chain provide the energy needed for the active transport of H+ ions from the stroma, across the thylakoid membrane, into the thylakoid space. The hydrophobic nature of the thylakoid membrane functions as a channel for the diffusion of H+ ions. The diffusion of H+ out of the thykaloid space provides the energy for the synthesis of ATP from ADP and inorganic phosphate. ATP synthase in the stalked particles catalyses the reaction.