Question

An analysis of a DNA (double stranded) sample yielded $18\%$ cytosine. What would be the percentage of other base ion this sample?

• A. T-32%, A-32%, G-18%
• B. T-32%, A-18%, G-32%
• C. T-18%, A-32%, G-32%
• D. T-40%, A-22%, G-20%

Answer 1

Answer: (B)

According to Chargaffs rule, in DNA purines and pyrimidines are always in equal proportion (ie, $A +G =T +C$) and proportion of adenine is always equals to that of thymine, while proportion of guanine always equals to that of cytosine (ie, $A = T$ and $G = C$). So, option a is correct.