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Article By:

Tanese, Naoko Department of Microbiology, New York University School of Medicine, New York, New York.

Wilson, Angus C. Department of Microbiology, New York University School of Medicine, New York, New York.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.800940

The process that occurs within a living cell in which an enzyme makes a ribonucleic acid (RNA) copy of the deoxyribonucleic acid (DNA) that contains the genetic information. The resulting RNA is often used as a template to make proteins by the cellular protein-synthesizing (translation) machinery. Transcription is an essential step in the growth and differentiation of all cells and contributes to almost every aspect of the development of an organism. Because transcription is so fundamental to life, there is significant conservation of proteins and enzymatic steps involved in transcription in cells of bacterial, archaeal, and eukaryotic origin. An RNA polymerase catalyzes synthesis of RNA from DNA by binding to a sequence termed the promoter located adjacent to or upstream of the coding portion of the linked gene. Genetic and biochemical studies have defined distinct steps in the transcriptional process. The first step of the transcription cycle is initiation, which involves melting (strand separation) of the template DNA and formation of the first chemical bond that makes the RNA. Like a revving engine, the RNA polymerase carries out several rounds of synthesis of short RNA transcripts (termed abortive transcripts) until it becomes disengaged from the promoter (promoter escape) and moves along the DNA, synthesizing RNA at an estimated rate of 1500 bases per minute. This step of the transcription cycle is called elongation, which is followed by termination and re-initiation. Transcription is a highly regulated process; each step requires participation of accessory proteins and is subject to control by transcription factors that respond to intra- and extracellular signals. See also: Deoxyribonucleic acid (DNA); Enzyme; Gene; Protein; Ribonucleic acid (RNA)

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