If a double stranded DNA has 20 per cent of cytosine, calculate the per cent of adenine in the DNA.

Question

Philoid · Accepted Answer

Its given that Cytosine = 20%. Hence according to Erwin Chargaff, Guanine = 20%. So, Cytosine + Guanine = 40% which makes Adenine + Thymine = 60%. Hence Adenine = 30%.

Explanation: Adenine is paired to Thymine by 2 hydrogen bonds. Cytosine is paired to Guanine by 3 hydrogen bonds. According to Erwin Chargaff, the ratios between Adenine & Thymine and Cytosine & Guanine are constant and equals one.

%A = %T and %C = %G