There are a few steps in the process of genetic engineering:
1. The desired characteristic is selected, and the gene responsible for this characteristic is located in the original organism.
2. Restriction enzymes are used to cut out the gene that is responsible for the characteristic. However, this leaves ‘sticky ends’ (sections of DNA that have unpaired bases).
3. Using the same restriction enzymes, the vector is cut, leaving complementary sticky ends.
4. The gene is inserted into a vector, which is usually a bacterial plasmid (a small circle of DNA) or a virus
5. The vector, usually a bacterial plasmid or a virus, is used to insert the gene into the cells of the target organism.
The gene must be inserted into the cells of the target organism during its early stages of development. In animals, this early stage is the embryo phase. This ensures that all the cells receive the gene and that the organism develops with the desired characteristics.
The diagram below shows the genetic engineering of E. coli (a type of bacteria) with a foreign gene.