Genetic engineering is the use of science to manipulate DNA molecules in order to create biological organisms or products that are useful to people. In other words, scientists use recombinant DNA techniques to alter and recombine genes, introduce them into different organisms, and create new types of living things. Two essential tools of genetic engineering are restriction enzymes and DNA ligase enzymes. Together, these enzymes make it possible to cut and paste recombinant DNA molecules . Another essential tool of genetic engineering is a class of DNA molecules known as a vectors .
Plasmids are the most common type of vector.
Vectors are short, specially-constructed DNA molecules for carrying, moving, and replicating a DNA sequence. This means that after creating recombinant DNA molecules in a test tube, recombinant molecules must be introduced into host cells for propagation. This process is called, transformation. Generally, this step leads to thousands of colonies, with each colony consisting of identical cells each containing identical recombinant DNA molecules. In the process of creating recombinant DNA molecules, it is necessary to select for those colonies that contain recombinant DNA molecules with the gene of interest.