Which enzyme is known for gluing together fragments of DNA during replication?

The enzyme responsible for gluing together fragments of DNA during replication is ligase. During the DNA replication process, particularly on the lagging strand, DNA is synthesized in short segments known as Okazaki fragments. As these fragments are synthesized, ligase plays a critical role in linking these segments by forming covalent bonds between the sugar and phosphate components of adjacent nucleotides. This action effectively creates a continuous strand of DNA. The function of ligase is crucial because without it, the DNA strands would remain fragmented, which would compromise the integrity and functionality of the genetic material.

In contrast, helicase unwinds the double-stranded DNA to allow replication to occur, while endonuclease and exonuclease are involved in cutting DNA. Endonuclease cuts within a strand of DNA, whereas exonuclease removes nucleotide units from the ends of a DNA strand. Ligase, however, specifically serves the key role of joining these fragments together, ensuring the DNA strand is complete and intact after replication.