Question

Which of the following restriction enzymes produces blunt ends ?

• A. Sal I
• B. Eco RV
• C. Xho I
• D. Hind III

Answer 1

The Correct Option is B

Restriction enzymes are enzymes that cut DNA molecules at specific sequences. They are essential tools in molecular biology for DNA cloning and analysis. Restriction enzymes can produce two types of ends after cutting: sticky ends and blunt ends. 

Let's evaluate the given options one by one to determine which enzyme produces blunt ends:

1. Sal I: This restriction enzyme recognizes the sequence \(5'-G\downarrow TCGA-3'\) and cuts in a manner that creates sticky ends with an overhang. Thus, it does not produce blunt ends.
2. Eco RV: It recognizes the sequence \(5'-GAT\downarrow ATC-3'\). Eco RV cuts straight across the DNA, so both strands end at the same place, producing blunt ends. This matches the requirement of the question, as it is the enzyme that produces blunt ends.
3. Xho I: This enzyme recognizes the sequence \(5'-C\downarrow TCGAG-3'\) and also creates sticky ends with an overhang, not blunt ends.
4. Hind III: This enzyme recognizes the sequence \(5'-A\downarrow AGCTT-3'\) and likewise produces sticky ends, not blunt ends.

Based on the above analysis, Eco RV is the restriction enzyme that produces blunt ends.

Restriction Enzyme	Recognition Sequence	Type of Ends Produced
Sal I	5'-G\downarrow TCGA-3'	Sticky Ends
Eco RV	5'-GAT\downarrow ATC-3'	Blunt Ends
Xho I	5'-C\downarrow TCGAG-3'	Sticky Ends
Hind III	5'-A\downarrow AGCTT-3'	Sticky Ends