Question

If the base adenine constitutes 31% of an isolated DNA fragment, then write what will be the expected percentage of the base cytosine in it. Explain how did you arrive at the answer given.

Hint:

The Chargaff’s rule states that in DNA, the percentage of \(A = T\) and \(C = G\), with the total equalling 100\%.

Answer 1

Adenine (\(A\)) pairs with Thymine (\(T\)), so \(A + T = 31\% + 31\% = 62\%\). Cytosine (\(C\)) pairs with Guanine (\(G\)), and since \(C + G = 100\% - (A + T) = 38\%\), the percentage of cytosine is \(C = 19\%\).