1. Scientists remove plasmids, small rings of DNA, from bacterial cells. 2. An enzyme cuts open the plasmid DNA. The same enzyme removes the human insulin gene from its chromosome.3. The human insulin gene attaches the open ends of the plasmid to form a closed ring.4. Some bacterial cells take up the plasmids that have the insulin gene.5. When cells reproduce, the news cells will contain copies of the engineered plasmid. The foreign gene directs the cell to produce human insulin.