Which strand of DNA is complementary to the sense strand?

The complementary strand to the sense strand of DNA is the antisense or template strand. The sense strand, also known as the coding strand, has the same sequence as the mRNA that is transcribed from the gene, with thymine (T) replaced by uracil (U) in RNA. The antisense strand is complementary to this sense strand and serves as the template for RNA synthesis during transcription.

When RNA polymerase synthesizes mRNA, it reads the antisense strand from 3' to 5', creating an mRNA strand that is synthesized in the 5' to 3' direction. This relationship ensures that the base pairing rules are followed—adenine (A) pairs with uracil (U) in RNA while cytosine (C) pairs with guanine (G).

Understanding this relationship is crucial, as it underlies the process of gene expression and the flow of genetic information from DNA to RNA and ultimately to protein. The other options, such as the messenger strand, coding strand, and promoter strand, either refer to the same strand in different contexts or do not represent a complementary relationship.