In the DNA molecule

Options

(a) the total amount of purine nucleotides and pyrimidine nucleotides is not always equal
(b) there are two strands which run parallel in the 5′ → 3′ direction
(c) the proportion of Adenine in relation to thymine varies with the organism
(d) there are two strands which run antiprallel one in 5′ → 3′ direction and other in 3′ → 5′

Correct Answer:

there are two strands which run antiprallel one in 5′ → 3′ direction and other in 3′ → 5′

Explanation:

In the DNA molecule, there are two strands which run anti parallel one is 5′ – 3′ direction and other in 3′ – 5′ direction, the two chains are held together by hydrogen bonds between their bases.Adenine (A), a purine of one chain his exactly opposite thymine (T), a pyramidine of the other chain. Similarly, cytosine (C), a pyrimidine lies opposite guanine (G), a purine. This allows a sort of lock & key arrangement between large sized purine & small sized pyrimidine. It is strengthened by the appearance of hy