The two strands in $DNA$ are not identical but are complementary. Explain.

(N/A) In the helical structure of $DNA$,the two strands are held together by hydrogen bonds between specific pairs of bases. $Cytosine$ $(C)$ forms hydrogen bonds with $Guanine$ $(G)$,while $Adenine$ $(A)$ forms hydrogen bonds with $Thymine$ $(T)$. Because of this specific base pairing,the sequence of one strand determines the sequence of the other,making them complementary rather than identical.