Question: 134: In the following palindromic base sequences of DNA, which one can be cut easily by particular restriction enzyme?
(1) 5’CTCAGT3′; 3’GAGTCA5′
(2) 5’GTATTC3′; 3’CATAAG5′
(3) 5’GATACT3′; 3’CTATGA5′
(4) 5’GAATTC3′; 3’CTTAAG5′
Answer: Option (4)
Explanation:
Restriction enzymes recognize and cut specific palindromic DNA sequences.
A palindromic sequence is one in which the sequence of bases reads the same in
the 5' \rightarrow 3' direction on both DNA strands.
The sequence 5’GAATTC3′ and 3’CTTAAG5′ is a well-known palindromic sequence.
This sequence is specifically recognized and cleaved by the restriction enzyme EcoRI.
EcoRI cuts between \mathrm{G} and \mathrm{A},
producing sticky ends that are useful in genetic engineering.
The other given sequences either do not form perfect palindromes or are not recognized
efficiently by common restriction enzymes.
Therefore, the sequence in Option (4) can be cut easily by a particular restriction enzyme.