What are the Products of Deamination of Cytosine and 5-Methyl

Question

What are the products of deamination of cytosine and 5-methyl cytosine, respectively?
A) Thymine and uracil
B) Thymine in both cases
C) Uracil and thymine
D) Uracil in both cases
E) Xanthine and hypoxanthine

Accepted Answer

The use of thymine instead of uracil by DNA has the advantage that deamination of cytosine (to uracil) can be readily detected as an abnormal base in DNA. However, deamination of 5-methyl cytosine (a modification that is found in vertebrate DNA) can produce thymine and lead to mutations at a higher rate.