Electron transport system and ATP synthesisइलेक्ट्रॉन परिवहन तंत्र और ATP संश्लेषण

NCERT Figs 12.4, 12.5 · interactive diagram

Parts and their functions

• Complex I (सम्मिश्र I) — NADH dehydrogenase; oxidises NADH from the matrix.
• Complex II (सम्मिश्र II) — Receives electrons from FADH₂ (succinate oxidation).
• Ubiquinone (यूबिक्विनोन) — Carrier in the inner membrane; reduced to ubiquinol.
• Complex III (सम्मिश्र III) — Cytochrome bc₁ complex; passes electrons to cytochrome c.
• Cytochrome c (साइटोक्रोम c) — Small protein on the outer surface of the inner membrane; mobile carrier III → IV.
• Complex IV (सम्मिश्र IV) — Cytochrome c oxidase (cyt a, a₃, two copper centres); gives electrons to O₂.
• Complex V — ATP synthase (सम्मिश्र V — ATP सिंथेज़) — F₀ = integral proton channel; F₁ = headpiece where ATP is made.
• NADH (NADH) — 1 NADH oxidised → 3 ATP.
• FADH₂ (FADH₂) — 1 FADH₂ oxidised → 2 ATP.
• Oxygen (ऑक्सीजन) — Final hydrogen/electron acceptor, reduced to water — drives the whole chain.
• Proton pumping (प्रोटॉन पंपन) — Energy of electron flow moves H⁺ out → gradient.
• ATP synthesis (ATP संश्लेषण) — 2 H⁺ through F₀ → 1 ATP at F₁ (oxidative phosphorylation).

Original diagram drawn by Simple Learning Hub, based on NCERT Figs 12.4, 12.5. Report a mistake