Question

The role of DNA ligase in the construction of a recombinant DNA molecules 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 pirine and pyrimidine bases.
• D. Formation of hydrogen bonds between blunt ends.

Answer 1

Answer: (A)

Formation of phosphodiester bond between two DNA fragments.

Purified DNA ligase is used in gene cloning to join DNA molecules together to construct recombinant DNA. DNA ligase is an enzyme, that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. Ligases can join any DNA fragments with 'blunt' ends. They can also join DNA fragments with 'sticky' ends, but only if the nucleotides on the strands are complementary.

So, the correct answer is 'Formation of the phosphodiester bond between two DNA fragments'.