The sticky or blunt ends refer to the properties of the end of DNA molecules, which are commonly generated by restriction enzymes that cut the DNA.

A straight cut of restriction enzymes generates blunt ends, where both strands terminate in a base pair. Blunt ends are also called non-cohesive ends, since there is no unpaired DNA strand fleeting at the end of DNA.

The sticky ends, a.k.a. cohesive ends, have unpaired DNA nucleotides on either 5’- or 3’- strand, which are known as overhangs. These overhangs are most often generated by a staggered cut of restriction enzymes. Sticky ends are generally more desired in cloning technology where a DNA ligase is used to join two DNA fragments into one, because the yield and specificity of ligation using sticky ends is significantly higher that with blunt ends.