Question

Which among the following restriction endonucleases will produce blunt ends?
I. BamH I
II. Hind II
III. EcoR I
IV. Hind III
V. Sal I

• A. I, IV
• B. Only III
• C. Only II
• D. III, IV

Answer 1

The correct option is C Only II

Restriction endonucleases are the enzymes that cleave the phosphodiester bonds present between consecutive nucleotides within or near to specific DNA sequences known as recognition sequences.

Blunt ends are produced when restriction enzymes cut both the strands of double stranded DNA in a straight manner at the same position. Therefore, both the stands in the DNA fragments have complementary base pairing.

Sticky ends are the single stranded, unpaired bases (overhangs) produced in the DNA fragments. This is possible when the restriction enzymes make staggered cuts on the double stranded DNA. It happens when the restriction enzyme cleaves at a point slightly away from the centre of the palindromic sequence, however between the same two bases.

BamH I, Hind II, EcoR I, Hind III and Sal I are the restriction enzymes obtained from certain strains of different bacteria.
Below is a table showing the type of DNA fragments produced by them:
Hence, only Hind II produces blunt ends.