There are a few steps in the process of genetic engineering:
1. The desired characteristic is selected.
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. The vector must be cut with the same restriction enzymes, which leaves complementary sticky ends
4. The gene is inserted into a vector.
5. The vector is used to insert the gene into the cells of the target organism.
The genes must be inserted into the cells of the target organism during the early stages of its development. In animals, the early stage of development is the early embryo stage. This is to ensure that all of 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.