What role does DNA ligase play in the creation of recombinant plasmids?

DNA ligase is an essential enzyme in the process of creating recombinant plasmids because it facilitates the joining of the gene of interest to the plasmid. During the recombinant DNA technology process, DNA fragments, including the target gene and the plasmid, typically have complementary sticky ends or overhangs created by restriction enzymes. DNA ligase acts by forming phosphodiester bonds between the adjacent nucleotides at the junction of these fragments, effectively sealing the nicks and creating a continuous strand of DNA. This action is crucial for ensuring that the gene of interest is properly integrated into the plasmid, allowing for its subsequent replication and expression within the host organism. This process is fundamental to genetic engineering, as it enables the transfer of specific traits or capabilities into a variety of organisms.