Question

If the total amount of adenine and thymine in a double-stranded DNA is $45\%$, the amount of guanine in this DNA will be

• A. $22.5\%$
• B. $27.5\%$
• C. $45\%$
• D. $55\%$

Answer 1

Answer: (B)

$27.5\%$

Answer 2

According to Chargaffs rule
$A + G = T + C$
$A+G=T+C$
In the given ds- DNA, the total amount of adenine and thymine is $45 \%$,
thus, the remaining $55 \%$ will be of cytosine and guanine.
Out of which, $27.5 \%$ ( $55 / 2$ ) will be of guanine.