Question

Which enzyme acts as “molecular glue” to join DNA fragments?

• A. DNA Polymerase
• B. DNA Ligase
• C. Helicase
• D. Restriction Endonuclease

Hint:

DNA ligase is essential in DNA replication for joining Okazaki fragments and in genetic engineering for creating recombinant DNA molecules.

Answer 1

The Correct Option is B

Concept:
DNA ligase is an important enzyme involved in DNA replication, repair, and genetic engineering. It is commonly called the “molecular glue” because it joins DNA fragments by forming phosphodiester bonds between adjacent nucleotides in the DNA backbone.

Step 1: Understand the need for DNA joining.
During DNA replication, especially on the lagging strand, short DNA fragments known as Okazaki fragments are produced. These fragments must be joined together to form a continuous DNA strand.

Step 2: Role of DNA ligase.
DNA ligase catalyzes the formation of phosphodiester bonds between the \(3'\)-OH end of one nucleotide and the \(5'\)-phosphate end of another, thereby sealing the break in the DNA strand.

Step 3: Application in biotechnology.
In recombinant DNA technology, restriction enzymes cut DNA into fragments, and DNA ligase joins these fragments together to form recombinant DNA molecules. \[ \boxed{\text{DNA Ligase}} \]