Question

In DNA $20\%$ bases are adenine. What percentage of bases are pyrimidines?

• A. 30%
• B. 60%
• C. 50%
• D. 20%

Answer 1

Answer: (C)

The percentage of bases which are pyrimidines is
$50\%$. According to Chargaff s rule
$A+G=C+T=50\%$
(Purines) (Pyramidines)
$\therefore A=20\%,$ then $T=20\%$
$C+T=50\%$
$C=50\%-20\%=30\%$
Total percentage of pyrimidine bases
$(T+C)$ are $20+30=50\%$