Restriction endonucleases are especially useful if they generate sticky ends. What makes an end sticky?

The question is incomplete as it does not have the options which are:

A) single-stranded complementary tails

B) blunt ends

C) poly-A sequences

D) 5' cap

E) interference

A) single stranded complementary tails

Explanation:

Restriction endonuclease is the enzyme which cuts the DNA sequence in the internal sequence.

The endonuclease enzyme can cut the DNA sequence in a way that it can form the cuts with the single-stranded overhangs called sticky ends and without overhangs called blunt ends.

The sticky ends are produced when the enzyme makes cut at the single strand and then makes the cut at between the same base at the nitrogenous base. This type of asymmetrical cut forms the single-stranded overhangs which can form the complementary base pairs easily.

Thus, Option-A is correct.