Question

In the following palindromic base sequence of DNA, which one can be cut easily by a particular restriction enzyme?

• A. 5’ GATACT 3’ ; 3’ CTATGA 5’
• B. 5’ GAATTC 3’ ; 3’ CTTAAG 5’
• C. 5’ CTCAGT 3’ ; 3’ GAGTCA 5’
• D. 5’ GTATTC 3’ ; 3’ CATAAG 5’

Answer 1

The Correct Option is B

Restriction enzymes are enzymes that cut DNA molecules at specific sequences of nucleotides. The particular sequence recognized by a restriction enzyme is called a restriction site, and these sites are often palindromic, where the sequence reads the same forward and backward. One such well-known restriction enzyme is EcoRI, which recognizes and cuts the palindromic sequence 5’ GAATTC 3’.

Given the options, we need to identify which DNA sequence can be easily cut by EcoRI:

• 5’ GATACT 3’ ; 3’ CTATGA 5’
• 5’ GAATTC 3’ ; 3’ CTTAAG 5’
• 5’ CTCAGT 3’ ; 3’ GAGTCA 5’
• 5’ GTATTC 3’ ; 3’ CATAAG 5’

Analyzing the options, we see that option (b) 5’ GAATTC 3’ ; 3’ CTTAAG 5’ is the sequence recognized by the enzyme EcoRI. This sequence is palindromic and matches the specific cutting site for EcoRI, allowing it to easily cleave the DNA at this point. Therefore, this is the correct answer.

Conclusion: Among the given sequences, the one that can be cut easily by a particular restriction enzyme EcoRI is 5’ GAATTC 3’ ; 3’ CTTAAG 5’.