Which component of ETC is not a protein ?

Options

A. Cytochrome
B. Ubiquinone
C. Cytochrome oxidase
D. All the above

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the component of the electron transport chain (ETC) that is not a protein. The options provided are cytochrome, ubiquinone, cytochrome oxidase, and all of the above.

2. **Identifying Components of the ETC**: The electron transport chain is a series of complexes involved in aerobic respiration, primarily located in the inner mitochondrial membrane. It consists of various proteins and coenzymes that facilitate the transfer of electrons.

3. **Analyzing the Options**:
- **Cytochrome**: This is a heme-containing protein that plays a crucial role in the electron transport chain. Therefore, it is a protein.
- **Ubiquinone**: Also known as coenzyme Q, ubiquinone is a lipid-soluble molecule (1,4-benzoquinone) and is not a protein. This makes it a potential answer to the question.
- **Cytochrome Oxidase**: This is an enzyme that contains cytochromes and is involved in the final step of the electron transport chain. It is also a protein.

4. **Conclusion**: Since ubiquinone is the only component listed that is not a protein, the correct answer is ubiquinone.

5. **Final Answer**: Ubiquinone is the component of the electron transport chain that is not a protein.

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