ATP Synthase Structure & Proton Flow — NEET Biology
✅ Asked in NEET 2023Which of the following combinations is required for chemiosmosis? 2023
Which of the following combinations is required for chemiosmosis? 2023
Answer & NCERT explanation
Correct answer: D — Membrane, proton pump, proton gradient, ATP synthase
Chemiosmosis requires four essential components according to NCERT: (1) A membrane to separate compartments, (2) Proton pumps to create concentration gradient, (3) Proton gradient (electrochemical potential), and (4) ATP synthase to utilize the gradient for ATP synthesis. Option (d) correctly lists all four requirements. Other options either mention NADP synthase (incorrect enzyme) or lack membrane component.
Read more NCERT concept on the PYQ
This complex consists of two major components, F₁ and F₀. The F₁ headpiece is a peripheral membrane protein complex and contains the site for synthesis of ATP from ADP and inorganic phosphate. F₀ is an integral membrane protein complex that forms the channel through which protons cross the inner membrane. The passage of protons through the channel is coupled to the catalytic site of the F₁ component for the production of ATP. For each ATP produced, 4H⁺ pass through F₀ from the intermembrane space to the matrix down the electrochemical proton gradient.
ATP synthase (Complex V) has two key parts: F₁ (headpiece where ATP is made) and F₀ (channel for protons). Protons flow through F₀ from the intermembrane space into the matrix, and this movement drives ATP synthesis in F₁. Students often confuse which direction protons move or forget that 4H⁺ ions are needed per ATP molecule. Remember: protons move DOWN their electrochemical gradient through F₀, and this energy directly powers the catalytic sites in F₁ to phosphorylate ADP into ATP. This is the final step of cellular respiration and a classic NEET topic.
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