There are three methods of DNA transfer in bacteria which give them genetic variation: 1. Transformation-process of transferring the foreign DNA into the bacteria DNA. Usually, bacteria take in DNA from its environment, which is DNA shed by other bacteria. 2. Transduction-process of transferring by viruses (bacteriophages). Bacteriophages that infect bacteria insert short pieces of chromosomal DNA from one bacterium to another. 3. Conjugation-process of DNA transfer (usually plasmids) from one bacterium to another via direct contact. Pili are the structures at the surface of bacteria that enable the process of conjugation.
