Reverse transcriptase was discovered by Howard Temin at the University of Wisconsin, also known as RNA directed DNA polymerase which synthesis DNA from RNA.

Taq polymerase derived from thermostable bacteria called thermus aquaticus.it is basically used in PCR and have the ability to withstand with 90°C temperature.

Nucleases are the enzymes which break phosphodiester bonds of DNA that link one nucleotide to another. Nucleases are of two types i.e., endonucleases and exonucleases.

Endonuclease are those which break internal phosphodiester bonds of DNA while exonuclease removes nucleotide from the end of the DNA. Examples: mung bean nuclease, S1 nuclease, Rnase A, and RNase H.

S1 nuclease has been derived from Aspergillus oryaze and used to degrade single strand RNA and DNA but does not affect ds DNA or DNA-RNA hybrid.