The two DNA strands are held against each other by hydrogen bonds. Determine the number of nucleotides with adenine

The two DNA strands are held against each other by hydrogen bonds. Determine the number of nucleotides with adenine, thymine, guanine and cytosine in a DNA molecule, in which 42 nucleotides are connected by two hydrogen bonds and 48 nucleotides by three hydrogen bonds. Explain the results.

1) the chains of the DNA molecule are connected according to the principle of complementarity: A – T, G – C;
2) two hydrogen bonds are formed between A and T, the total number of nucleotides (in two DNA chains): A + T = 42, therefore,
A = T = 42: 2 = 21;
3) three hydrogen bonds are formed between G and C, the total number of nucleotides (in two DNA chains): G + C = 48, therefore,
G = C = 48: 2 = 24.

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