Lesson eLearning

Which of the following is a palindromic DNA sequence recognized and cut by the restriction enzyme EcoRI?

easy MCQ 1 mark Class 12 · Biology · Biotechnology Principles and Processes
  1. 5'-GAATTC-3' / 3'-CTTAAG-5'
  2. 5'-GGATCC-3' / 3'-CCTAGG-5'
  3. 5'-AAGCTT-3' / 3'-TTCGAA-5'
  4. 5'-TCTAGA-3' / 3'-AGATCT-5'
Answer
5'-GAATTC-3' / 3'-CTTAAG-5'

The correct answer is 5'-GAATTC-3' / 3'-CTTAAG-5' — Hence the correct choice is option A.

Step-by-step solution

  1. Recall that EcoRI recognises a specific 6‑base pair palindromic sequence.
  2. Identify the sequence that reads the same 5'→3' on both strands when complementary bases are considered.
  3. Option A (5'-GAATTC-3' / 3'-CTTAAG-5') satisfies the palindromic requirement and is the known EcoRI site.
  4. Hence the correct choice is option A.
Common mistake: Choosing a non‑palindromic sequence or confusing EcoRI with other enzymes

Concept tested: Restriction enzymes and palindromic sites

Published · How this solution was prepared and checked

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