question_answer 25)

  The role of DNA ligase in the construction of a recombinant DNA molecule is (a) formation of phosphodiester bond between two DNA fragments (b) formation of hydrogen bonds between sticky ends of DNA fragments (c) ligation of all purine and pyrimidine bases (d) None of the above

Answer:

                  (a) DNA ligase (joining or sealing enzymes) are also called genetic gum. They join two individual fragments of double-stranded DNA by forming phosphodiester bonds between them. Thus they help in sealing gaps in DNA fragments. Therefore, they actas a molecular glue.