Out of six protons extruded into outer mitochondrial chamber, only two are available form `NADH+H^(+)`. The others come form

Options

A. `FADH_(2)`
B. `NADPH+H^(+)`
C. Matrix
D. Both A and B.

Answer

To solve the question, we need to understand the process of oxidative phosphorylation and the role of different electron carriers in the electron transport chain.

### Step-by-Step Solution:

1. **Understanding Oxidative Phosphorylation**:
- Oxidative phosphorylation occurs in the mitochondria and is responsible for the production of ATP. It involves the electron transport chain and the generation of a proton gradient across the inner mitochondrial membrane.

2. **Role of Electron Carriers**:
- NADH and FADH2 are the primary electron carriers that donate electrons to the electron transport chain. As electrons are passed along the chain, protons (H⁺ ions) are pumped from the mitochondrial matrix into the outer mitochondrial chamber.

3. **Proton Contribution**:
- In the given scenario, it is stated that out of six protons extruded into the outer mitochondrial chamber, only two are derived from NADH + H⁺. This indicates that NADH contributes to the proton gradient.

4. **Identifying the Source of Remaining Protons**:
- The question asks where the remaining four protons come from. Since NADH contributes two protons, we need to identify the other source.
- FADH2 is another electron carrier that also contributes to the electron transport chain, but it enters the chain at a different point than NADH, resulting in fewer protons being pumped compared to NADH.

5. **Conclusion**:
- The remaining protons (four protons) are contributed by FADH2. Therefore, the correct answer to the question is that the other protons come from FADH2.

### Final Answer:
The other protons come from **FADH2**.

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