We begin our detailed study of transcription by looking at the synthesis and processing of mRNAs, the molecules that make up the transcriptome and which specify the protein content of the cell.

DNA transcription, also known as RNA synthesis is the process by which genetic information that is contained in DNA is re-written into messenger RNA (mRNA) by an RNA polymerase enzyme. The synthesized mRNA is transported out of the cell nucleus where it will later on aid in the synthesis of proteins by the mechanism of translation.

RNA is synthesized from its 5′ end to its 3′ end, antiparallel to its DNA template strand (see p. 463). The template is copied as it is in DNA synthesis, in which a guanine (G) on the DNA species a cytosine (C) in the RNA , a C species a G, a T species an A , but an A species a U instead of a T (Fig. 31. 5). The RNA , then, is

In vitro transcription (IVT) is a simple procedure that allows for template-directed synthesis of RNA molecules of any sequence from short oligonucleotides to those of several kilobases in μg to mg quantities [1].

Transcription begins with the opening and unwinding of a small portion of the DNA double helix to expose the bases on each DNA strand. One of the two strands of the DNA double helix then acts as a template for the synthesis of an RNA molecule.