When and where does it happen, why is it important please and ty
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Definitions first. Photophosphorylation is the production of ATP using sunlight. It involves photosystems II and I (in that order), linked by an electron transport chain. Photosystems are embedded in the thylakoid membrane, and absorb light using chlorophyll and other pigments. The light absorbed energizes an electron in photosystem, and so on. (Check photosynthesis)
Anyways, to answer your question. When: Light is absorbed by photosystem. Electron received by electron acceptor, then passed on to electron transport chain. Electron loses energy, used to pump H+ ions into thylakoid space. This creates a proton gradient, which drive ATP synthesis by ATP synthase, when the H+ exits the thylakoid space through the synthase.
Where: Thylakoid. Across the thylakoid membrane. In the chloroplast.
By the way, there are two forms of photophosphorylation. In non-cyclic photophosphorylation, the electron is eventually transferred to NADP to form NADPH. In cyclic, it is transferred from photosystem I (the later one) back to the electron transport chain.
And, it is important as it produces ATP and NADPH, used for subsequent steps of photosynthesis.
Hope this helps. And I apologise for being so long-winded.
Anyways, to answer your question. When: Light is absorbed by photosystem. Electron received by electron acceptor, then passed on to electron transport chain. Electron loses energy, used to pump H+ ions into thylakoid space. This creates a proton gradient, which drive ATP synthesis by ATP synthase, when the H+ exits the thylakoid space through the synthase.
Where: Thylakoid. Across the thylakoid membrane. In the chloroplast.
By the way, there are two forms of photophosphorylation. In non-cyclic photophosphorylation, the electron is eventually transferred to NADP to form NADPH. In cyclic, it is transferred from photosystem I (the later one) back to the electron transport chain.
And, it is important as it produces ATP and NADPH, used for subsequent steps of photosynthesis.
Hope this helps. And I apologise for being so long-winded.