AP BIOLOGY

Detailed explanation-1: -DNA ligases catalyze the formation of phosphodiester bonds between adjacent 5′P and 3′OH ends in the backbone of double-stranded DNA and have a conserved core structure comprising the catalytic adenylation (AD) domain and an oligonucleotide-binding (OB) domain joined by a flexible linker region (1).

Detailed explanation-2: -DNA ligases play an essential role in maintaining genomic integrity by joining breaks in the phosphodiester backbone of DNA that occur during replication and recombination, and as a consequence of DNA damage and its repair.

Detailed explanation-3: -DNA ligase catalyzes a phosphodiester bond formation between adjacent 3′-OH and 5′-P termini of the nick DNA. The insertion of oxidized or mismatch nucleotide by a DNA polymerase could confound the next DNA ligation step during single-stranded and double-stranded DNA repair.

Detailed explanation-4: -DNA ligases catalyze the formation of phosphodiester bonds between juxtaposed 5’ phosphate and a 3’-hydroxyl terminus in duplex DNA. This activity can repair single-stranded nicks in duplex DNA and join duplex DNA restriction fragments having either blunt ends or homologous cohesive ends.

Detailed explanation-5: -DNA ligase is used to join two fragments of DNA to seal the gaps between them. Thus, they are known as molecular glues.