complementary DNA

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complementary DNA (cDNA) A form of DNA prepared in the laboratory using messenger RNA (mRNA) as template, i.e. the reverse of the usual process of transcription in cells; the synthesis is catalysed by reverse transcriptase. cDNA thus has a base sequence that is complementary to that of the mRNA template; unlike genomic DNA, it contains no noncoding sequences (introns). cDNA is used in gene cloning for the expression of eukaryote genes in prokaryote host cells, or as a gene probe to locate particular base sequences in genomic DNA.

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