in Biotechnology and its Applications by

1 Answer

0 votes
by

Enzymes in recombinant DNA technology are used to make specific changes in the DNA molecules that are being manipulated. These enzymes are classified into four categories as follows:

(1) Nucleases: These enzymes are used to cut, shorten or degrade nucleic acid molecules (DNA and RNA). These are of 2 types:

[i] Exonucleases- These remove nucleotide molecules from the end of DNA.

[ii] Endonucleases- These enzymes break internal phosphodiester bonds within DNA or RNA

E.g.: Restriction enzyme or restriction endonuclease, Exonuclease, S1 nuclease, Deoxyribonuclease I (DNase I)

(2) Polymerases: These enzymes are used for making copies of DNA molecules from DNA or RNA template. E.g.: DNA polymerase  I, Reverse Transcriptase

(3) Ligases: These enzymes are used to join DNA molecules. E.g.: DNA ligase, T4 ligase

(4) Modifying enzymes: These enzymes are used to make changes at the end of the DNA molecules by adding or removing chemical groups. E.g.: Polynucleotide kinase, Alkaline phosphatase.

Biology Questions and Answers for Grade 10, Grade 11 and Grade 12 students, Junior and Senior High Schools, Junior Colleges, Undergraduate biology programs and Medical Entrance exams.
...