Conceptually, producing a recombinant DNA molecule simply involves cutting and pasting.

1. DNA molecules from two different sources are cut with the same restriction enzyme to form DNA molecules with "sticky" complementary single stranded ends;
2. A circular plasmid from a bacterium is frequently used as the target DNA into which the novel DNA will be transferred;
3. The recombinant DNA is constructed by mixing the two types of molecules so that their cohesive ends pair.
4. DNA ligase then forms covalent 5'-3' phosphodiester bonds between the junctions of the two molecules.

1. Vaccine development - The surface antigen of Plasmodium falciparum, one of the 4 species of malaria has been transferred to E. coli to produce amounts large enough to develop a vaccine against this form of malaria. It works well enough for people who will visit a malarious region for a relatively short period of time (military personnel, tourists, mission workers)
2. Hormone development - Human synthetic versions of insulin (Humulin™), erythropoietin (Procrit™), growth hormone, granulocyte stimulating factor are available.
3. Gene therapy for genetic diseases - Still in the experimental stages, it may be possible to transfer the gene for normal adult hemoglobin into marrow stem cells of an individual with sickle-cell anemia. The goal is to promote the growth of enough cells to produce enough normal hemoglobin to alleviate the symptoms of sickle-cell anemia. One hundred percent (100%) is NOT required to attain the alleviation of symptoms.
4. Diagnostic kit development - The test kit for the rickettsial bacterium which causes Lyme Disease tests for the presence of an antigen specific to the surface of this bacterium. The gene for that antigen was extracted, transferred to a plasmid and then implanted into a strain of E. coli. The correct diagnosis of this disease is crucial for a favorable prognosis and treatment.

A. Disease resistance in food and ornamental plants -