GENETIC ENGINEERING Human Cell DNA 1 Isolation Cells are broken open using chemicals and enzymes releasing the DNA from the human cell and the plasmid from the bacterial cell. Bacterial Cell Plasmid 2 Cutting Restriction enzymes recognise specific sites and cut the human DNA isolating the gene of interest. The same restriction enzyme is used to cut the plasmid. Human DNA Restriction enzyme Restriction enzyme Sticky end 3 Transformation The gene of interest is inserted into the plasmid. The sticky ends of the human DNA complementary pair with the sticky ends of the plasmid. Gene of interest Sticky end Recombinant Plasmid An enzyme DNA ligase bonds the sticky ends of the human DNA and plasmid together 4. Expression The recombinant plasmid is inserted back into a bacterial cell. The bacterial cell reproduces producing the polypeptide coded for by the donor DNA. Bacterial cell reproduces by binary fission. Kerry Teacher Design Team in association with the Biology Support Service, The Education Centre, Tralee