Transcription

Making an RNA copy from a sequence of DNA (a gene). Transcription is the first step in gene expression.

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Transfer of genetic code information from one kind of nucleic acid to another, especially with reference to the process by which a base sequence of messenger RNA is synthesized (by an RNA polymerase) on a template of complementary DNA.

- reverse t. reversal of the normal pattern of t. (from DNA to RNA); the effective means is the viral enzyme reverse transcriptase.

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tran·scrip·tion tran(t)s-'krip-shən n the process of constructing a messenger RNA molecule using a DNA molecule as a template with resulting transfer of genetic information to the messenger RNA compare REVERSE TRANSCRIPTION, TRANSLATION

tran·scrip·tion·al -shnəl, -shən-əl adj

tran·scrip·tion·al·ly -ē adv

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n.

the process in which the information contained in the genetic code is transferred from DNA to RNA: the first step in the manufacture of proteins in cells. See messenger RNA, translation.

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trans·crip·tion (trans-kripґshən) [L. transcriptio transfer, copy] the process by which a single-stranded RNA with a base sequence complementary to one strand of a double-stranded DNA is synthesized. The enzymes involved are called DNA-dependent RNA polymerases (see under polymerase).

Transcription. Binding of the RNA polymerase at a specific site on DNA to be transcribed (A) is followed by unwinding of a region of the DNA helix and initiation of transcription in a 5′ to 3′ direction (B), producing an RNA transcript complementary to, and hydrogen-bonded with, the template strand of the DNA. The transcript elongates as the polymerase proceeds down the DNA (C), with the helix unwinding before and rewinding after it.