One molecule of `FADH_(2)` upon oxidative phosphorylation yields

Options

A. 2 ATP
B. 3 ATP
C. 4 ATP
D. 5 ATP

Answer

To determine how many ATP molecules are produced from one molecule of FADH₂ during oxidative phosphorylation, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of FADH₂**: FADH₂ is a reduced coenzyme that plays a crucial role in cellular respiration. It is produced during the Krebs cycle and is involved in the electron transport chain (ETC).

2. **Identify the Entry Point in the ETC**: FADH₂ enters the electron transport chain at a lower energy level compared to NADH. Specifically, FADH₂ donates its electrons to Complex II (succinate dehydrogenase), while NADH donates its electrons to Complex I.

3. **ATP Yield from FADH₂**: Each time electrons pass through the ETC, protons are pumped across the mitochondrial membrane, creating a proton gradient. This gradient is used by ATP synthase to produce ATP.
- Since FADH₂ enters the ETC at Complex II, it results in the pumping of fewer protons compared to NADH, which enters at Complex I.
- The general yield from FADH₂ is approximately 1.5 ATP per molecule of FADH₂, but in many contexts, it is rounded to 2 ATP.

4. **Conclusion**: Therefore, one molecule of FADH₂ upon oxidative phosphorylation yields **2 ATP molecules**.

### Final Answer:
One molecule of FADH₂ upon oxidative phosphorylation yields **2 ATP molecules**.

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