15. What is the role of DNA ligase in genetic engineering? A. To cut DNA sequences B. To copy DNA C. To join DNA fragments together D. To isolate DNA

The correct answer is C. To join DNA fragments together.<br /><br />DNA ligase is an enzyme that plays a crucial role in genetic engineering. Its primary function is to catalyze the formation of a phosphodiester bond between two DNA fragments, effectively joining them together. This process is essential in various genetic engineering techniques, such as DNA cloning, where DNA ligase is used to seal the gaps between the inserted gene and the plasmid vector, allowing the recombinant DNA to be expressed in the host organism.