What is the difference between sticky ends and blunt ends produced by restriction enzymes?

• A. Sticky ends have no overhangs.
• B. Blunt ends have overhanging single-stranded ends.
• C. Sticky ends are produced by enzymes that cut away base pairs.
• D. Sticky ends have overhanging single-stranded ends that can anneal with complementary ends; blunt ends have straight cuts with no overhangs.

Answer: (D)

The difference comes from how restriction enzymes cut the DNA to create ends that influence how fragments can be joined. Some cuts are staggered, leaving short single-stranded overhangs on one or both ends. These overhangs, called sticky or cohesive ends, can pair with complementary overhangs on another fragment, guiding correct alignment for ligation. Other enzymes cut straight across both DNA strands at the same position, producing blunt ends with no overhangs; without overhangs, there’s no easy base-pairing guide, so joining relies purely on ligase and is less efficient.

That’s why the statement describing sticky ends as having overhanging single-stranded ends that can anneal with complementary ends, while blunt ends are straight cuts with no overhangs, is the best description.