AP BIOLOGY

Detailed explanation-1: -Blunt-ended fragments can be joined to each other by DNA ligase.

Detailed explanation-2: -T4 DNA ligase can promote the in vitro ligation of blunt DNA ends to ends bearing a 2-nucleotide single-stranded protrusion. This was shown by digestion of plasmids pBR322 and pSP71 with the appropriate restriction enzymes followed by recircularization of the plasmids and transformation of Escherichia coli.

Detailed explanation-3: -T4 DNA Ligase is a ligation enzyme that can be used to join DNA fragments by catalyzing the formation of phosphodiester bonds between juxtaposed 5’ phosphate and 3’ hydroxyl termini in double-stranded DNA using ATP as a coenzyme.

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: -The enzyme DNA polymerase then moves along the exposed DNA strand, joining newly arrived nucleotides into a new DNA strand that is complementary to the template. Figure 1 shows the process part way through.