Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A): Restriction endonuclease is used to cut DNA molecules for cloning.
Reason (R): Restriction endonuclease enzyme cut DNA molecule of any source into unique short pieces in a sequence specific manner.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Restriction enzymes act as "molecular scissors". Their sequence specificity allows molecular biologists to predictable cut and paste DNA fragments from different organisms, which is the foundation of genetic engineering. EcoRI cuts specifically at:
5'-G $\downarrow$ AATTC-3'
3'-CTTAA $\uparrow$ G-5'

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Restriction endonucleases are bacterial enzymes that cleave double-stranded DNA at specific recognition sequences, serving as a primary tool in recombinant DNA technology.

Step 2: Detailed Explanation:
1. Assertion Analysis: In molecular cloning, restriction endonucleases are used to cleave vector and target DNA molecules at precise locations, generating compatible ends (sticky or blunt) that can be ligated together. Thus, the Assertion is true.
2. Reason Analysis: Restriction endonucleases recognize specific palindromic sequences (typically 4 to 8 base pairs in length) in DNA from any biological source and introduce clean phosphodiester backbone cuts. This sequence specificity ensures that digesting a given DNA molecule always yields the same set of unique fragments, validating the Reason.
3. Since this highly specific, reproducible cleavage mechanism is the exact reason why restriction enzymes are suitable for precise DNA manipulation and cloning, the Reason is the correct explanation of the Assertion.

Step 3: Final Answer:
Both (A) and (R) are true, and (R) is the correct explanation of (A).