Question

Assertion : Genetic engineering requires both nucleases and ligases.
Reason : Ligases produce the nick in the recombinant $DNA$ molecule.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (C)

Nucleases are the enzymes that remove nucleotides or produce nick in the $DNA$ strand. Exonudeases remove nucleotides from the free ends of $DNA$ while endonucleases produce internal nicks in $DNA$. Now, the desired gene is inserted and then the cut ends are sealed with the help of $DNA$ ligases. Ligases are also called molecular glue as they join together two $DNA$ strands by forming phosphodiester bonds between adjacent nucleotides.