Which one of the following is incorrect statement for mitochondrial ETC and oxiative phosphorylation?

Options

A. Enzyme complex I accepts electrons and `H^(+)` from NADH and `FADH_(2)`
B. Passage of protons through the channel is coupled to the catalytic site of the `F_(1)` for ATP production
C. Cytochrome-c is a mobile protein attached to outer surface of inner membrane
D. `6H^(+)` passes thorugh `F_(0)` from intermembrane space to the matrix down the electrochemical proton gradient to produce 3ATP

Answer

To answer the question regarding which statement is incorrect about the mitochondrial electron transport chain (ETC) and oxidative phosphorylation, we will analyze each option provided in the question.

### Step-by-Step Solution:

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

2. **Analyzing the Statements**:
- **Statement 1**: "Enzyme complex first accepts the electron and proton from NADH and FADH2."
- **Analysis**: This statement is incorrect. Complex I (NADH dehydrogenase) accepts electrons from NADH, but it does not accept electrons from FADH2. FADH2 donates its electrons to Complex II (succinate dehydrogenase).

- **Statement 2**: "Passes of proton through the channel is coupled to the catalytic site of the F1 for ATP production."
- **Analysis**: This statement is correct. The flow of protons through the F0 channel is coupled to ATP synthesis at the F1 site, where ATP is produced from ADP and inorganic phosphate.

- **Statement 3**: "Cytochrome c is a mobile protein attached to the outer surface of the inner membrane."
- **Analysis**: This statement is also correct. Cytochrome c is a mobile electron carrier that is loosely associated with the outer surface of the inner mitochondrial membrane.

- **Statement 4**: "The 6 protons pass through F0 from intermembrane space to the matrix down the electrochemical proton gradient to produce 3 ATP."
- **Analysis**: This statement is correct. It is known that the movement of protons through the ATP synthase complex (F0) results in the synthesis of ATP, with approximately 2 protons needed to produce 1 ATP molecule.

3. **Conclusion**:
- The incorrect statement among the options is **Statement 1**: "Enzyme complex first accepts the electron and proton from NADH and FADH2." This is the correct answer to the question.

### Final Answer:
The incorrect statement is: **"Enzyme complex first accepts the electron and proton from NADH and FADH2."**

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