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Which of the following restriction enzymes generates 5′‑overhang sticky ends when it cleaves DNA?

easy MCQ 1 mark Class 12 · Biology · Biotechnology Principles and Processes
  1. EcoRI
  2. SmaI
  3. HaeIII
  4. AluI
Answer
EcoRI

The correct answer is EcoRI — Therefore the enzyme that creates sticky 5′‑overhangs is EcoRI.

Step-by-step solution

  1. Identify the cutting pattern of each listed enzyme.
  2. EcoRI recognises the palindromic sequence 5′‑GAATTC‑3′ and cuts between G and A, producing 5′‑overhangs.
  3. SmaI cuts at CCC GGG producing blunt ends.
  4. HaeIII cuts at GG CC producing blunt ends.
  5. AluI cuts at AG CT producing blunt ends.
  6. Therefore the enzyme that creates sticky 5′‑overhangs is EcoRI.
Common mistake: Confusing enzymes that give blunt ends with those that give sticky ends

Concept tested: Restriction enzymes and type of DNA ends

Published · How this solution was prepared and checked

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