Conjugation is one of several mechanisms that bacteria use to transfer DNA, and hence new genetic information, between two cells. The other primary mechanisms are transformation, in which free DNA is transported across the cell membrane, and transduction, in which DNA is carried into the recipient cell by a bacterial virus.

The Role of Plasmids

Conjugation is about as close as single cells come to engaging in sex, and some of the terminology used to describe the process reflects that similarity. Conjugation, or mating, is a process of genetic transfer that requires cell-to-cell contact. The genetic instructions for conjugation are encoded on a double-stranded, circular piece of DNA. The circular DNA exists in the bacterial cell entirely separate from the much larger bacterial chromosome. Scientists refer to this specialized, extrachromosomal piece of DNA as a conjugative plasmid or a "fertility factor." Cells that possess it are donor or...