 The use of ligation enzymes allows DNA fragments to be connected . By binding ( " ligating " ) fragments of DNA together from different sources , researchers can create recombinant DNA , the DNA often associated with genetically modified organisms . Recombinant DNA is commonly used in the context of plasmids : short circular DNA molecules with a few genes on them . In the process known as molecular cloning , researchers can amplify the DNA fragments by inserting plasmids into bacteria and then culturing them on plates of agar ( to isolate clones of bacteria cells ) . ( " Cloning " can also refer to the various means of creating cloned ( " clonal " ) organisms . ) 
