Genetic Transformation

Transformation is the consequence of the introduction and incorporation of foreign genetic material, such as DNA or RNA, into a cell that brings about alteration of the genetic makeup. It was first discovered in 1928 by Dr. Frederick Griffith, and subsequently in 1944, Drs. Oswald T. Avery, Colin M. MacLeod, and Maclyn McCarty demonstrated that the gene transfer in bacteria Streptococcus pneumoniae was through DNA. Nowadays, genes from unrelated species can be combined in laboratories using molecular biology techniques which facilitate production of therapeutics such as insulin.

In single-cell organisms such as bacteria, genetic transformation can be achieved in laboratory setting using strains such as Escherichia coli. Foreign genetic materials can be transferred to these bacteria either naturally or artificially. Some species of bacteria routinely take up foreign genetic materials from their surrounding environment that is thought be used as a source of nucleotides. It has been suggested that this uptake of foreign genetic information might have been developed through evolution to allow the organisms to gain ability to adapt to their environment. The second way to accomplish genetic transformation in organisms is via artificial methods utilizing either thermal (heat shock) or electrical (electroporation) means. Both methods involve making the cell walls permeable for the entry of genetic material, such as DNA, into the cells.

In multicell organisms, such as plants, genetic transformation can also be achieved using particle bombardment or biolistics, which involves coating small gold or tungsten particles with DNA and then shooting them into plant cells. This process randomly incorporates DNA of interest into the plant genome.

In addition, foreign DNA can be introduced into mammalian cells DNA via transfection (heat shock or liposome-based methods), microinjection (injection of DNA directly into the cells using tiny needles), or viral transduction (delivery of genetic material packaged in virus to target host cells). Mammalian cells can sometimes be rendered tumorigenic when viral genes, such as oncogenes, transform normal cells into those with abnormal cellular appearance and properties regulating growth, proliferation, or differentiation.