Question

If a dsDNA has 20% adenine, what would be its cytosine content?

(a) 20%

(b) 30%

(c) 40%

(d) 80%

Answer 1

Answer is : (b) 30%

If dsDNA has 20% adenine, then according to the Chargaff’s rule, it would have 20% thymine. The remaining 60% represents both G + C. Since guanine and cytosine are always present in equal numbers, the percentage of cytosine molecule is 30%.