Topic summary
Blunt ends

Extracted from the Wikipedia article Sticky and blunt ends.
Blunt ends
The simplest DNA end of a double stranded molecule is called a blunt end. Blunt ends are also known as non-cohesive ends. In a blunt-ended molecule, both strands terminate in a base pair. Blunt ends are not always desired in biotechnology since when using a DNA ligase to join two molecules into one, the yield is significantly lower with blunt ends. When performing subcloning, it also has the disadvantage of potentially inserting the insert DNA in the opposite orientation desired. On the other hand, blunt ends are always compatible with each other. Here is an example of a small piece of blunt-ended DNA: