The importance of sticky ends

• If the recognition site is cut in a staggered fashion by a restriction endonuclease, the cut ends of the DNA double strand is left with a single strand which is a few nucleotide bases long.
• If the same restriction endonuclease is used to cut DNA, then all the fragments produced will have ends that are complementary to each other. This means that the single-stranded end of any one fragment can be stuck to the single-stranded end of any other fragment (sticky ends).
• Once the complementary bases of two sticky ends have paired up, an enzyme (DNA ligase) is used to bind the phosphate-sugar framework of two sections of DNA.
• Sticky ends have considerable importance because, provided that the same restriction endonuclease is used, they allow recombinant DNA to be formed from the DNA of different organisms.