Question

Deamination of adenine and guanine by HNO${}_2$ and UV rays produces

• A. Cytosine and Uracil
• B. Xanthine and Hypoxanthine
• C. Hypoxanthine and Xanthine
• D. Xanthine and Uracil

Answer 1

Answer: (C)

Hypoxanthine and Xanthine

Mutations in organism also occur if any damage is caused to its DNA. The damage can be caused by environmental factors, such as radiation and chemicals like mutagens. Sometimes damage can also be caused by some mechanism like hydrolysis. Hydrolysis leads to deamination and depurination. In deamination, amine group is removed from the molecule. Deamination of adenine by $HN{O}_2$ and UV rays produces hypoxanthine. It makes hydrogen bonds with cytosine rather than with thymine. Deamination of guanine by $HN{O}_2$ and UV rays produces xanthine. It continues to make hydrogen bonds with cytosine, but it makes only two hydrogen bonds.