Cyanide affects which complex of ETC?

Options

A. complex I
B. complex III
C. complex IV
D. complex V

Answer

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

1. **Understanding the Electron Transport Chain (ETC):**
- The Electron Transport Chain (ETC) is a series of complexes involved in cellular respiration where electrons are transferred through a series of proteins to ultimately produce ATP.
- There are four main complexes in the ETC: Complex I, Complex II, Complex III, and Complex IV.

2. **Identifying the Role of Cyanide:**
- Cyanide is a potent inhibitor of cellular respiration. It disrupts the normal function of the ETC.
- It specifically targets one of the complexes within the ETC, which prevents the cells from utilizing oxygen effectively.

3. **Locating the Affected Complex:**
- In the context of the ETC, cyanide binds to the E3 portion of Complex IV, which is also known as cytochrome oxidase.
- Complex IV is responsible for the final step of the electron transport chain where oxygen is used as the terminal electron acceptor.

4. **Understanding the Consequences of Cyanide Binding:**
- When cyanide binds to Complex IV, it prevents the transfer of electrons to oxygen.
- This blockage leads to a halt in ATP production and can result in cell death due to lack of energy.

5. **Conclusion:**
- Therefore, the complex affected by cyanide in the Electron Transport Chain is Complex IV.

**Final Answer:**
Cyanide affects Complex IV of the Electron Transport Chain.

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