The main purpose of electron transport chain is to -

Options

A. Cycle `NADH^(+)` + `H^(+)` back to `NAD^(+)`
B. Use the intermidiates from TCA cycle
C. breakdown pyruvate
D. All

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Electron Transport Chain (ETC):** The Electron Transport Chain is a series of protein complexes and other molecules that transfer electrons from electron donors like NADH and FADH2 to electron acceptors, ultimately leading to the production of ATP.

2. **Role of NADH and FADH2:** NADH and FADH2 are generated during glycolysis and the Krebs cycle (TCA cycle). They carry high-energy electrons that are essential for the process of oxidative phosphorylation.

3. **Oxidation of NADH and FADH2:** In the ETC, NADH and FADH2 are oxidized, meaning they lose electrons. This process converts NADH back to NAD+ and FADH2 back to FAD. This recycling is crucial because NAD+ and FAD are necessary for glycolysis and the Krebs cycle to continue functioning.

4. **Production of ATP:** As electrons move through the chain, their energy is used to pump protons (H+) across the mitochondrial membrane, creating a proton gradient. This gradient is then used by ATP synthase to produce ATP from ADP and inorganic phosphate.

5. **Conclusion:** The main purpose of the Electron Transport Chain is to recycle NADH and FADH2 back to NAD+ and FAD, allowing for continuous energy production through cellular respiration.

**Final Answer:** The main purpose of the Electron Transport Chain is to recycle NADH and FADH2 back to NAD+ and FAD, facilitating ATP production.

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