It is caused by mutations in the gene that helps an enzyme called phenylalanine hydroxylase, or PAH. <span />
1. Scientist remove plasmids, small rings of DNA, from bacterial cells
2. An enzyme cuts open the plasmids DNA. The same enzymes removes the human insulin gene from its chromosomes
3. The human insulin gets attaches the open ends of the plasmids to form a closed ring
4. Some bacterial cells take up the plasmids that have the insulin gene
5. When cells reproduce, the new cells will contain copies of the engineered
plasmids. The foreign gene directs the cell to reproduce human insulin.
