Explanation:
In molecular biology, transformation is the genetic alteration of a cell resulting from the direct absorption, incorporation and expression of exogenous genetic material (exogenous DNA). Exogenous DNA is found in the environment and is introduced through the cell membrane. The transformation occurs naturally in some species of bacteria, although it can also be done by artificial means. For the transformation to occur, the bacteria must be in a state of competition, which can occur as a time-limited response to environmental conditions, such as lack of nutrients and high cell density. A transformation is one of three processes by which exogenous genetic material can be introduced into a bacterial cell. The other two are conjugation and transduction. The transformation of eukaryotic cells is called transfection.
The term transformation is also used, more generally, to describe mechanisms of DNA or RNA transfer in molecular biology (that is, taking into account more than the genetic consequences). For example, the production of transgenics such as transgenic corn requires the insertion of new genetic information into the corn genome using the appropriate DNA transfer mechanism; The process is commonly called transformation.
RNA can also be transferred into cells using similar methods, but this does not normally cause heritable changes and therefore is not a real transformation.
