conjugation

1. The union of two unicellular organisms or of the male and female gametes of multicellular forms followed by partition of the chromatin and the production of two new cells. 2. Bacterial c., effected by simple contact, usually by means of specialized pili through which transfer genes and other genes of the plasmid are transferred to recipient bacteria. 3. Sexual reproduction among protozoan ciliates, during which two individuals of appropriate mating types fuse along part of their lengths; their macronuclei degenerate and the micronuclei in each macronucleus divide several times (including a meiotic division); one of the resulting haploid pronuclei passes from each conjugant into the other and fuses with the remaining haploid nucleus in each conjugant; the organisms then separate (becoming exconjugants), undergo nuclear reorganization, and subsequently divide by asexual mitosis. 4. The combination, especially in the liver, of certain toxic substances formed in the intestine, drugs, or steroid hormones with glucuronic or sulfuric acid; a means by which the biologic activity of certain chemical substances is terminated and the substances made ready for excretion. 5. The formation of glycyl or tauryl derivatives of the bile acids. 6. An alternating sequence of multiple and single chemical bonds in a chemical compound in which there is some delocalization of π-electrons. 7. The joining together of two compounds. [L. con-jugo, pp. -jugatus, to join together]

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con·ju·ga·tion .kän-jə-'gā-shən n

1) the act of conjugating: the state of being conjugated

2 a) fusion of usu. similar gametes with ultimate union of their nuclei that occurs in most fungi and in some algae (as green algae)

b) temporary cytoplasmic union with exchange of nuclear material that is the usual sexual process in ciliated protozoans

c) the one-way transfer of DNA between bacteria in cellular contact

con·ju·ga·tion·al -shnəl, -shən-əl adj

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n.

the union of two microorganisms in which genetic material (DNA) passes from one organism to the other. In bacteria minute projections on the donor 'male' cell (pili) form a bridge with the recipient 'female' cell; the exact function of the pili is not known, but they are believed to have an important role in conjugation.

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con·ju·ga·tion (kon″jə-gaґshən) [L. conjugatio a blending] 1. the act of joining together or conjugating, or the state of being joined or conjugated. 2. a sexual process seen in bacteria, ciliate protozoa, and certain fungi in which nuclear material is exchanged during the temporary fusion of two cells (conjugants). In bacterial genetics, a form of sexual reproduction in which a donor bacterium (male) contributes some, or all, of its DNA (in the form of a replicated set) to a recipient (female), which then incorporates differing genetic information into its own chromosome by recombination and passes the recombined set on to its progeny by replication. In ciliate protozoa, two conjugants of separate mating types exchange micronuclear material and then separate, each now being a fertilized cell. In certain fungi, the process involves fusion of two gametes, resulting in union of their nuclei and formation of a zygote. 3. in chemistry, the joining together of two compounds to produce another compound, such as the combination of a toxic product with a substance in the body to form a detoxified product that can then be eliminated, or the binding of tumor-specific monoclonal antibodies to cytotoxic drugs in immunotherapy.