Gene Cloning
You probably have heard of cloning. A clone is a genetically exact copy. It can be a clone of a gene, a cell or an organism.
Gene cloning, also known as molecular cloning, refers to the process of isolating a DNA sequence of interest for the purpose of making multiple copies of it. The identical copies are clones.
Recombinant DNA is engineered through the combination of two or more DNA strands, combining DNA sequences which would not normally occur together. In other words, selected DNA (or the DNA of "interest") is inserted into an existing organismal genome, such as a bacterial plasmid DNA, or some other sort of vector.
The recombinant DNA can then be inserted into another cell, such as a bacterial cell, for amplification and possibly production of the resulting protein. This process is called transformation, the genetic alteration of a cell resulting from the uptake, incorporation, and expression of foreign genetic material.
Recombinant DNA technology was made possible by the discovery of restriction endonucleases. loning of a segment of DNA of interest can easily be carried out with restriction enzyme digestion, followed by ligation and transformation or transfection. In the classical restriction enzyme digestion and ligation cloning protocols, cloning of any DNA fragment essentially involves four steps: isolation of the DNA of interest (or target DNA), ligation, transfection (or transformation), and a screening/selection procedure.