Chemiosmotic ATP Synthesis in Chloroplasts — NEET Biology
✅ Asked in NEET 2024Let us now try and understand how actually ATP is synthesised in the chloroplast. The chemiosmotic hypothesis has been put forward to explain the mechanism. Like in respiration, in photosynthesis too, ATP synthesis is linked to development of a proton gradient across a membrane. This time these are the membranes of thylakoid. There is one difference though, here the proton accumulation is towards the inside of the membrane, i.e., in the lumen. In respiration, protons accumulate in the intermembrane space of the mitochondria when electrons move through the ETS (Chapter 12).
NTA tests whether students understand that ATP synthesis in photosynthesis relies on a proton gradient across thylakoid membranes, similar to the chemiosmotic mechanism in mitochondria. The key trap: students confuse the location of proton accumulation—in chloroplasts, protons accumulate INSIDE the thylakoid lumen, while in mitochondria they accumulate in the intermembrane space. Remember: in both organelles, the proton gradient drives ATP synthase, but the anatomical location differs due to different membrane structures. This concept bridges photosynthesis and respiration, making it highly testable for integrated understanding of cellular energy production.
Synthesis of ATP linked to development of a proton gradient across a membrane is: (NEET 2024)
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