Practice question

Adaptor ligation uses short synthetic duplex oligonucleotides of ten to twenty base pairs engineered to carry compatible sticky ends without requiring internal cleavage. Adaptors are formed by annealing two partially complementary oligonucleotides, generating a double-stranded region with one cohesive extension that matches ends created by restriction enzymes. When incubated with target fragments and T4 DNA ligase, adaptors covalently attach, modifying termini for subsequent insertion into vectors. This approach surpasses blunt-end cloning in efficiency, avoids exonuclease trimming, and is fundamental for next-generation sequencing library preparation, cDNA cloning, and addition of defined ends.