Answer:
join DNA fragments by the formation of phosphodiester bonds.
Step-by-step explanation:
DNA ligase is an enzyme which has the role to join fragments of DNA after they are being cleaved with endonucleases. This enzyme is also important in DNA replication, because it links the ends after the excision of primer in lagging DNA strand.
DNA ligase is also used in the cloning of DNA: vector DNA and foreign DNA contain compatible ends(after treatment with the same restriction enzymes) that can be joined together by molecular ligation via DNA ligase enzyme.