Complementary DNA

In genetics, complementary DNA (cDNA) is DNA synthesized from a mature mRNA template. cDNA is often used to clone eukaryotic genes in prokaryotes.

Overview

The central dogma of genetics outlines that in synthesizing proteins, DNA is transcribed into mRNA, which is translated into protein. One difference between eukaryotic and prokaryotic mRNA is that eukaryotic mRNA can contain introns (intervening sequences), which are not coding sequences, per se, and must be spliced out of the mRNA before it is translated into protein. Prokaryotic mRNA has no introns, so it is not subject to splicing.

Related Topics:
Central dogma of genetics - Protein - DNA - Transcribed - MRNA - Translated - Intron - Spliced - Splicing

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Often it is desirable to express eukaryotic genes in prokaryotic cells. A simplified method of doing so would include the addition of eukaryotic DNA to a prokaryotic host, which would transcribe the DNA to mRNA and then translate it to protein. However, as eukaryotic DNA has introns, and since prokaryotes lack the machinery to splice them, the splicing of eukaryotic DNA must be done prior to adding the eukaryotic DNA into the host (as well, before placing the eukaryotic DNA into the prokaryote, it must be methylated and a prokaryotic promoter region must be added). This spliced DNA is called complementary DNA.

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