Sticky End (Cohesive End)
Definition
A single-stranded overhang generated when two cuts on opposite strands of a DNA duplex are offset rather than directly opposite each other. Complementary sticky ends from two fragments cut with the same enzyme can base-pair, facilitating ligation.
- Structure
- Single-stranded overhang on cut DNA
- Cause
- Offset cuts on opposite strands of a DNA duplex
- Function
- Base-pairs with a complementary sticky end to enable ligation
Common questions
Why do molecular cloning protocols favour restriction enzymes that leave sticky ends over blunt ends?+
Complementary sticky ends base-pair before ligase seals the strand, which orients and holds the fragment and vector together far more efficiently than blunt ends, which have no sequence-based way to align and rely on chance collision.
Can sticky ends from two different restriction enzymes join together?+
Only if the two enzymes happen to produce identical overhanging sequences, since ligation requires the single-stranded overhangs to be complementary; otherwise the ends will not base-pair and must be blunted or adapted before joining.
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