conjugation
conjugation A process whereby organisms of identical species (but opposite mating types) pair and exchange genetic material (DNA); i.e., each individual may both give and receive material. This process of sexual reproduction is found only in unicellular organisms, although the term is sometimes also applied to the union of gametes, particularly in isogamy (found in fungi and some green algae). The gametes are not released into the external environment. (E.g., in Spirogyra a conjugation tube, formed by the fusion of protuberances from conjugating cells, acts as a passageway for the gamete of the cell to move into another cell and fuse with its nucleus.) Details of the process differ greatly between different organisms. For example, in bacteria only DNA is transferred from one cell to another, while in some eukaryotic microbes the process may involve the fusion of two entire protoplasts. The transfer of DNA may be unidirectional (as in the case of Escherichia coli), in which case one cell is called the donor and the other the recipient, or bi-directional (as in Paramecium aurelia).
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conjugation