Question

Which one of the following mutagens convert DNA’s adenine to hypoxanthine?

• A. Ultraviolet light
• B. Mitomycin C
• C. Methyl methanesulfonate
• D. Nitrous acid

Hint:

Nitrous acid is a mutagen that deaminates adenine, converting it to hypoxanthine and causing base substitution in DNA.

Answer 1

The Correct Option is D

Step 1: Understanding the process.
Nitrous acid is a mutagen that deaminates adenine, converting it to hypoxanthine. Hypoxanthine then pairs with cytosine during DNA replication, leading to a base pair substitution.
Step 2: Analyzing the options.
- (A) Incorrect, ultraviolet light causes thymine dimers, not base substitutions.
- (B) Incorrect, Mitomycin C is a cross-linking agent and does not deaminate adenine.
- (C) Incorrect, Methyl methanesulfonate adds methyl groups to DNA but does not convert adenine to hypoxanthine.
- (D) Correct, Nitrous acid deaminates adenine to hypoxanthine, causing base substitution.
Step 3: Conclusion.
The correct answer is (D) Nitrous acid.