AP BIOLOGY

Detailed explanation-1: -During transcription, the DNA of a gene serves as a template for complementary base-pairing, and an enzyme called RNA polymerase II catalyzes the formation of a pre-mRNA molecule, which is then processed to form mature mRNA (Figure 1).

Detailed explanation-2: -The upper strand of DNA is the “mRNA-like” strand. The lower strand is the strand that is complementary to the mRNA.

Detailed explanation-3: -Figure 2: RNA polymerase (green) synthesizes a strand of RNA that is complementary to the DNA template strand below it. Once RNA polymerase and its related transcription factors are in place, the single-stranded DNA is exposed and ready for transcription.

Detailed explanation-4: -Template strand is the DNA strand off which the mRNA is synthesized. The coding, or non-template, strand is the DNA strand complementary to the template strand; it has the same sequence (except for T for U substitutions) as the mRNA.

Detailed explanation-5: -In transcription, a portion of the double-stranded DNA template gives rise to a single-stranded RNA molecule. In some cases, the RNA molecule itself is a “finished product” that serves some important function within the cell.