Question

Assertion :Restriction enzymes cut the strand of DNA to produce sticky ends. Reason: Stickiness of the ends facilitates the action of the enzyme DNA polymerase.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is C Assertion is correct but Reason is incorrect.

Restriction enzyme, a type of an endonuclease, functions by inspecting the length of a DNA sequence. Once, it finds a recognition sequence, it binds and cut each of the two strands of the double helix at a specific point leaving single stranded portions at the ends. This results in overhanging stretches called as sticky ends. These are named so because they form hydrogen bonds with their complementary counterparts, i.e., they can join similar complementary ends of DNA fragment from some other source with the help of DNA ligase. This stickiness of the ends facilitates the action of the enzyme DNA ligase, not DNA polymerase.

Thus, the correct answer is option C.