Because the central dogma runs DNA → mRNA → protein and the genetic code is a defined mapping, the pathway can in principle be inverted: a known amino acid sequence implies its mRNA sequence via the codon table, and reverse transcriptase — an enzyme that synthesizes DNA from an RNA template — converts that transcript into complementary DNA (cDNA), a single-stranded molecule that DNA polymerase renders double-stranded. Amplifying this double-stranded product by inserting it into a cloning vector propagated in bacteria yields enough material to sequence, and depositing the resulting sequences in a searchable database constitutes a DNA library, a repository allowing a protein of interest to be looked up and its corresponding genetic sequence retrieved. The topic belongs to molecular biology and biotechnology, specifically recombinant DNA methodology.
Because the central dogma runs DNA → mRNA → protein and the genetic code is a defined mapping, the pathway can in principle be inverted: a known amino acid sequence implies its mRNA sequence via the …