DNA ligase is an essential enzyme in molecular biology that plays a crucial role in the process of DNA replication and repair. It functions by joining together two strands of DNA, sealing the gaps between them. This action is vital for maintaining the integrity of the genetic material, especially during cell division. In addition to its role in replication, DNA ligase is also important in various laboratory techniques, such as cloning and genetic engineering. By facilitating the joining of DNA fragments, it allows scientists to create recombinant DNA molecules, which can be used for research, therapeutic applications, and the development of genetically modified organisms.