Deamination of adenine and guanine by `HNO_(2)` produces :-

Options

A. Cytosine and uracil
B. Xanthine nd hypoxanthine
C. Hypoxanthine and xanthine
D. Xanthine and uracil

Answer

To solve the question regarding the deamination of adenine and guanine by nitrous acid (HNO₂), we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Deamination**:
- Deamination is a chemical reaction where an amine group (−NH₂) is removed from a molecule. In the context of nucleotides, this process can lead to changes in the nitrogenous bases of DNA.

2. **Identifying the Bases**:
- The bases in question are adenine and guanine. Both are purines, which are a type of nitrogenous base found in DNA and RNA.

3. **Deamination of Adenine**:
- When adenine undergoes deamination, it loses its amine group. The product of this reaction is hypoxanthine. Hypoxanthine is structurally similar to adenine but lacks the amine group.

4. **Deamination of Guanine**:
- Similarly, when guanine is deaminated, it also loses its amine group. The product of this reaction is xanthine. Like hypoxanthine, xanthine is a derivative of guanine.

5. **Conclusion**:
- Therefore, the deamination of adenine produces hypoxanthine, and the deamination of guanine produces xanthine.

6. **Final Answer**:
- The correct answer to the question is that the deamination of adenine and guanine by nitrous acid produces hypoxanthine and xanthine.