Question

During non cyclic photophosphorylation, how does (NADP +) become NADPH.

Answer 1

Hint: A two-stage process involving two separate photosystems of chlorophyll is non-cyclic photophosphorylation. Non-cyclic photophosphorylation in the thylakoid membrane occurs as a light reaction.

Complete answer:
Two photosystems occur in eukaryotes and certain prokaryotes. The first is called photosystem II (PSII), which was named for its discovery order rather than for the feature order. Energy from sunlight is used to remove electrons from water after a photon reaches the photosystem II (PSII) reaction core. The electrons pass to Photosystem I (PSI) through the chloroplast electron transport chain, which decreases NADP+ to NADPH.

The electron movement through the electron transport chain fuels the proton pumps present in the membrane and helps to transfer hydrogen ions towards the concentration gradient from the stroma side to the thylakoid lumen. Water separation appears to inject protons into the lumen at the same time, resulting in the elimination of NADPH. Inside the thylakoid lumen, which results in a high concentration of protons (H+) but a low concentration of stroma protons. The enzyme ATP synthase uses this electrochemical gradient to make ATP, similar to the way it is used in cellular respiration. A high concentration of a proton means an acidic pH, rendering the lumen of the thylakoid more acidic (lower) than the stroma.

Note: If the plant has an adequate reduction agent (NADPH), there is no need to generate more NADPH involving all photosystems (I and II). Photosystem I is only involved in cyclic photophosphorylation. Therefore, at this time, the cyclic one is required because it can produce ATP at less cost.