When decoding the nut genome, it was found that in a fragment of a DNA molecule the proportion of nucleotides with thymine is 20%.

When decoding the nut genome, it was found that in a fragment of a DNA molecule the proportion of nucleotides with thymine is 20%. Using Chargaff’s rule describing the quantitative relationships between different types of nitrogenous bases in DNA (G + T = A + C), calculate the amount (in%) in this sample of nucleotides with guanine.

Adenine (A) is complementary to thymine (T), and guanine (G) is complementary to cytosine (C), therefore the number of complementary nucleotides is the same; Chargaff’s rule: (A + T) + (G + C) = 100%
By condition T = 20%
G + C = 100% – (20% + 20%) = 60%
G = C = 60%: 2 = 30%