Question

Which of the following restriction enzymes produces blunt ends?

• A. Xho I
• B. EcoR V
• C. Sal I
• D. Hind III

Answer 1

The correct option is B EcoR V

Restriction endonuclease
Restriction endonucleases are the enzymes which cleave the DNA by digesting phosphodiester bonds at the specific sequences within the DNA. Examples include EcoR I.

Types of cleavage by REN
Restriction endonucleases cut DNA in two different ways as follows:
● Blunt cuts result in non-cohesive or blunt ends.
● Staggered cuts result in cohesive or sticky ends.●
Blunt ends
Blunt ends are formed when the restriction enzymes cut the DNA strands in such a way that the both strands terminate in a base pair. There are no unpaired nucleotides at the end of the DNA molecule.

Sticky ends
Sticky end is a fragment of DNA produced by a staggered cut using restriction enzymes, in which the terminal portion has a stretch of unpaired nucleotides.

\ Xho I
Restriction enzymes Xho I, is obtained from Xanthomonas holcicola. It produces sticky ends by making the following cut in the recognition sequence.

5 '- C↓TCGAG - 3'
3’ - GAGCT↑C - 5’

Hind III
Restriction enzyme Hind III is obtained from Haemophilus influenzae. It produces sticky ends by making the following cut in the recognition sequence.

5' - A↓AGCTT - 3'
3’ - TTCGA↑A - 5’

Sal I
Restriction enzyme Sal I is obtained from Streptomyces albus. It produces sticky ends by making the following cut in the recognition sequence.

5 '- G↓TCGAC - 3'
3’ - CAGCT↑G - 5’

EcoR V
Restriction enzyme EcoR V is obtained from Escherichia coli. It produces blunt ends by making the following cut in the recognition sequence.

5' - GAT↓ATC - 3’
3’ - CTA↑TAG - 5’

Final answer
(D) EcoR V