Genetic engineering involves the joining together of DNA from different sources and the introduction of the joined material into a suitable bacterial or eukaryotic cell in which it can replicate and be expressed. The potential of this exciting technique is evidenced by the synthesis of insulin by recombinant cells, by the transfer of nitrogen-fixing ability to new host species, by the production of interferon, “ bugs” for the treatment of oil spills, by the production of monoclonal antibodies, presently being used in the treatment of certain types of cancerous tumors. Genetic engineering is not a new process. The transfer of DNA between cells use a natural phenomenon in bacteria and a pertinent factor in bacterial evolution. Plasmids play a key role in natural genetic engineering in bacteria and are essential tools of recombinant DNA technology. This kit provides the student with the opportunity of demonstrating plasmid transfer between bacterial strains. In a simple experiment, the student can change the genetic makeup of a cell by the acquisition of a plasmid from a donor cell. By the creation, in the test tube, of a strain which is newly-resistant to the test antibiotic, the student strikingly illustrates the basic goal of genetic engineering research.