Question

If in a double-stranded DNA total 100 base pairs are present out of these 40 nucleotides have G, find out that
i) How many nucleotides have A and C?
ii) Which base pair is maximum in this DNA?

Answer 1

In double stranded DNA, purines (Adenine and Guanine) pair with pyrimidines (Thymine and Cytosine).

Adenine (A) pairs with Thymine (T) with two hydrogen bonds and Guanine (G) pairs with Cytosine (C) with three hydrogen bonds.

Thus, amount of A is equal to T and amount of G is equal to C

(i) So, out of 100 base pairs, if 40 are G, then C will also be 40

As (A + T) + (G+C) = 100, so A + T = 100 - (40 + 40) = 100 - 80 = 20

and A = T = 20/2 = 10

So, nucleotides having A are 10 and nucleotides having C are 40

(ii) In this DNA, base pairs G and C are maximum as they are present in 40 nucleotides.