Question

The two strands in DNA are not identieal but are complementary. Explain.

Answer 1

In the helical structure of DNA, the two strands are held together by hydrogen bonds between specific pairs of bases. Cytosine forms a hydrogen bond with guanine, while adenine forms a hydrogen bond with thymine. As a result, the two strands are complementary to each other.

In another way, the two stands in DNA molecule are held together by hydrogen bonding, which is according to a specific rule. Adenine is bound thymine and guanine to cytosine. Due to this base pairing principle, the sequence of bases in one strand automatically fixes the sequence of bases in the other stand. Thus, the two strands are not identical but are complimentary.