NEETZoologyBiotechnology - Principles and Processes
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Restriction endonuclease EcoRI produces sticky ends on the DNA fragments. Reason (R): EcoRI cuts the DNA helix a little away from the centre of the palindromic sites, but between the same two bases on the opposite strands. In the light of the above statements, choose the correct answer from the opt
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (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
Correct answer
A. Both (A) and (R) are true and (R) is the correct explanation of (A)
Step-by-step solution
Assertion (A) is true. Restriction endonuclease EcoRI cuts DNA to produce single-stranded overhanging stretches called sticky ends. Reason (R) is also true and provides the correct explanation for the Assertion. The sticky ends are formed precisely because the enzyme cuts the DNA helix a little away from the centre of the palindromic recognition sequence, but between the same two bases on the opposite strands. This staggered cleavage leaves single-stranded overhangs on each fragment. Therefore, both (A) and (R) are