A self-replicating (autonomous) circle of DNA distinct from the chromosomal genome of bacteria. A plasmid contains genes normally not essential for cell growth or survival. Some plasmids can integrate into the host genome, be artificially constructed in the laboratory, and serve as vectors (carriers) in cloning.
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A genetic particle physically separate from the chromosome of the host cell (chiefly bacterial) that can stably function and replicate and usually confer some advantage to the host cell; not essential to the cell's basic functioning. SYN: extrachromosomal element, extrachromosomal genetic element, paragene. [cytoplasm + -id]
- bacteriocinogenic plasmids bacterial plasmids responsible for the elaboration of bacteriocins. SYN: bacteriocin factors, bacteriocinogens.
- conjugative p. a p. that can effect its own intercellular transfer by means of conjugation; this transfer is accomplished by a bacterium being rendered a donor, usually with specialized pili. SYN: infectious p., transmissible p..
- F p. the prototype conjugative p. associated with conjugation in the K-12 strain of Escherichia coli. SYN: fertility factor, sex factor.
- infectious p. SYN: conjugative p..
- nonconjugative p. a p. that cannot effect conjugation and self-transfer to another bacterium (bacterial strain); transfer depends upon mediation of another (and conjugative) p..
- R plasmids SYN: resistance plasmids.
- resistance plasmids plasmids carrying genes responsible for antibiotic (or antibacterial drug) resistance among bacteria (notably Enterobacteriaceae); they may be conjugative or nonconjugative plasmids, the former possessing transfer genes (resistance transfer factor) lacking in the latter. SYN: R factors, R plasmids, resistance factors, resistance-transferring episomes.
- transmissible p. SYN: conjugative p..

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plas·mid 'plaz-məd n an extrachromosomal ring of DNA that replicates autonomously and is found esp. in bacteria compare EPISOME

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plas·mid (plazґmid) [plasm + -id] an extrachromosomal self-replicating structure found in bacterial cells that carries genes for a variety of functions not essential for cell growth. Plasmids consist of cyclic double-stranded DNA molecules, replicating independently of the chromosomes and transmitting through successive cell divisions genes specifying such functions as antibiotic resistance (R plasmid); conjugation (F plasmid); the production of enzymes, toxins, and antigens; and the metabolism of sugars and other organic compounds. Plasmids can be transferred from one cell to another by conjugation and by transduction. Some plasmids may also become integrated into the bacterial chromosome; these are known as episomes.

Medical dictionary. 2011.

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Look at other dictionaries:

  • Plasmid — Plas mid, n. (Molecular genetics) A piece of DNA, usually circular, functioning as part of the genetic material of a cell, not integrated with the chromosome and replicating independently of the chromosome, but transferred, like the chromosome,… …   The Collaborative International Dictionary of English

  • plasmid — plasmid. См. плазмида. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Plasmid — Plasmid, außerhalb des Bakterienchromosoms bei Protocyten in Ein oder Mehrzahl im Cytoplasma liegendes kleines, ringförmiges DNA Molekül, das ebenfalls genetische Information enthält und sich autonom repliziert. Ein P. kann z.B. Resistenzgene… …   Deutsch wörterbuch der biologie

  • plasmid — 1952, from PLASMA (Cf. plasma) + id …   Etymology dictionary

  • plasmid — [plaz′mid] n. [ PLASM(A) + ID] a small, DNA containing, self reproducing cytoplasmic element that exists outside the chromosome, as in some bacteria: because it can alter a hereditary characteristic when introduced into another bacterium, it is… …   English World dictionary

  • Plasmid — Figure 1: Illustration of a bacterium with plasmid enclosed showing chromosomal DNA and plasmids. In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA …   Wikipedia

  • Plasmid — Abb. 1: Schematische Darstellung eines Bakteriums mit chromosomaler DNA (1) und Plasmiden (2) …   Deutsch Wikipedia

  • plasmid — /plaz mid/, n. Microbiol. a segment of DNA independent of the chromosomes and capable of replication, occurring in bacteria and yeast: used in recombinant DNA procedures to transfer genetic material from one cell to another. [1950 55; PLASM +… …   Universalium

  • plasmid — (plaz mid) A double stranded DNA molecule that can exist and replicate independently of the chromosome or may be integrated with it. A plasmid is stably inherited, but is not required for the host cell s growth and reproduction …   Dictionary of microbiology

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