Complementary DNA

Complementary DNA (cDNA, complementary DNA) genes constitute the double-stranded DNA molecule with a single strand as a template, the transcription produce its complementary sequence of messenger RNA molecules, and then in the role of the enzyme reverse transcriptase, to mRNA molecules as a template, with a synthetic mRNA sequence complementary single-stranded DNA, and then to single-stranded DNA template for the synthesis of another with complementary single-stranded DNA, the two complementary single-stranded DNA molecule to form a double-stranded cDNA molecules. As a result, double-stranded molecule of the cDNA sequences With the transcription of the mRNA molecules have the gene are the same. Therefore, a cDNA molecules on behalf of a gene. CDNA, but still different from the genes because genes produce mRNA transcription, the number of non-coding sequences of introns that have been removed, reservations Only the coding sequence, that is, the exons. CDNA sequences so than the much shorter sequences, as in cDNA gene does not include the non-coding sequences --- intron.