Which function does DNA ligase serve in molecular biology?

DNA ligase plays a crucial role in molecular biology by joining DNA fragments together through the formation of phosphodiester bonds. This process is essential during DNA replication and repair, as it ensures that the backbone of DNA is continuous and stable. Specifically, DNA ligase catalyzes the joining of the 3' hydroxyl of one nucleotide to the 5' phosphate of another, effectively sealing nicks in the DNA.

This joining is particularly important in processes such as the ligation of Okazaki fragments during lagging strand synthesis in DNA replication and in the recombination and repair of damaged DNA. By creating a continuous strand, DNA ligase helps maintain the integrity and functionality of the genetic material, which is vital for proper cellular function and replication.