What is reverse transcription and when is it used?

Reverse transcription is the synthesis of DNA from an RNA template, catalyzed by reverse transcriptase enzyme. This produces complementary DNA (cDNA) which represents expressed genes without introns. Applications include: RT-PCR for detecting and quantifying RNA expression, cDNA library construction for studying expressed genes, and cloning of coding sequences without introns for protein expression. Common reverse transcriptases include M-MLV (Moloney Murine Leukemia Virus) and AMV (Avian Myeloblastosis Virus). The process requires RNA template, primers (oligo-dT, random hexamers, or gene-specific), dNTPs, and the enzyme.