Techniques for gene cloning enable scientists to prepare multiple identical copies of gene-sized pieces of DNA.
Most methods for cloning pieces of DNA share certain general features.
For example, a foreign gene is inserted into a bacterial plasmid and this recombinant DNA molecule is returned to a bacterial cell.
Every time this cell reproduces, the recombinant plasmid is replicated as well and passed on to its descendents.
Under suitable conditions, the bacterial clone will make the protein encoded by the foreign gene.