The number of hydrogen bonds formed between adenine and thymine and that formed between guanine and cytosine are respectively

Options

A. 3 and 2
B. 2 and 3
C. 2 and 2
D. 3 and 3

Answer

B

Explanation

`DNA` consists of two polynucleotide stands coiled aroung each other in a helix. The sugar - phosphate backbone is on the outside of the helix, and the amine bases are on the inside, so that a base on one strand points directly in towards a base on the second strand. The two strands run in opposite directions and are held together by hydrogen bond between pairs bases. Adenine `(A)` and thymine `(T)` form two strong hydrogen bonds to each other, but not to G or C while G and C form three strong hydrogen bonds to each other, but not to `A` or `T` . As a result, sample of `DNA` having more `GC` content has higher melting temperature `(T_(m))`.