Question

Question 26:                                                                                                 (20 marks)

List and explain the functions of 5 different types of enzymes that can be used to modify DNA. Explain how each might be used in cloning DNA or in analysis of a cloning experiment.

Answer 1

Enzymes used in cloning are -

1) restriction endonuclease - cleaves DNA at specific base sequence and cause double stand break.itvis used to create double strand break in plasmid .

2) ligase - this is used to join plasmis and gene of interest, help in involve in formation of recombinant molecule.

3) ALP - help in removing phosphate from ends of plasmid after RE digestion, thus prevent recirculization.

4) reverse transcriptase (Rt) - used in cDNA cloning. In cDNA cloning mRNA is used as starting material, RT convert mRNA to cDNA thus use in cloning.

5) terminal transferase - add homopolymer tail to the 3' end of a linear duplex.