The synthesis of ATP by photophosphorylation depends on a pair of coupled reactions. One involves an electron transport chain and the second involves ATP synthase. Describe the second coupled reaction that involves the ATP synthase. Which process or reaction is exergonic and which is endergonic
Due to light energy electrons are excited and move from PS2 to PS1 and then to NADPH in the stroma. As the electrons move from one elctron carrier to other, the H+ ions are passed into thulakoid lumen from stroma along with splitting of water in lumen results in H+ conc. Increase and Decrease of stromal H+ conc. ( Also because of NADPH formation).
As, a result, H+ conc. Gradient is formed across membrane. ATP synthase enzym transferred these H+ ions back to stroma by breaking the gradient energy and coupled with that, it starts using that energy for formation of ATP on the stroma side due to conformational change in structure.
Light harvesting is endergonic and AtP formation is exergonic.
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