plasmid

plas·mid

P0354800 (plăz′mĭd)n. A circular, double-stranded unit of DNA that replicates within a cell independently of the chromosomal DNA. Plasmids are most often found in bacteria and are used in recombinant DNA research to transfer genes between cells.

plasmid

(ˈplæzmɪd) n (Genetics) a small circle of bacterial DNA that is independent of the main bacterial chromosome. Plasmids often contain genes for drug resistances and can be transmitted between bacteria of the same and different species: used in genetic engineering[C20: from plasm + -id¹]

plas•mid

(ˈplæz mɪd)

n. a strand or loop of DNA that exists independently of the chromosome in bacteria and yeast and that is capable of genetic replication: used in recombinant DNA procedures as a vehicle of gene transfer. [1952]

Thesaurus

Noun

plasmid - a small cellular inclusion consisting of a ring of DNA that is not in a chromosome but is capable of autonomous replicationplasmid DNAcellular inclusion, inclusion body, inclusion - any small intracellular body found within another (characteristic of certain diseases); "an inclusion in the cytoplasm of the cell"

Translations

Plasmid

A circular extrachromosomal genetic element that is ubiquitous in prokaryotes and has also been identified in a number of eukaryotes. In general, bacterial plasmids can be classified into two groups on the basis of the number of genes and functions they carry. The larger plasmids are deoxyribonucleic acid (DNA) molecules of around 100 kilobase (kb) pairs, which is sufficient to code for approximately 100 genes. There is usually a small number of copies of these plasmids per host chromosome, so that their replication must be precisely coordinated with the cell division cycle. The plasmids in the second group are smaller in size, about 6–10 kb. These plasmids may harbor 6–10 genes and are usually present in multiple copies (10–20 per chromosome). See Gene

Plasmids have been identified in a large number of bacterial genera. Some bacterial species harbor plasmids with no known functions (cryptic plasmids) which have been identified as small circular molecules present in the bacterial DNA. The host range of a particular plasmid is usually limited to closely related genera. Some plasmids, however, are much more promiscuous and have a much broader host range.

The functions specified by different bacterial plasmids are usually quite specialized in nature. Moreover, they are not essential for cell growth since the host bacteria are viable without a plasmid when the cells are cultured under conditions that do not select for plasmid-specified gene products. Plasmids thus introduce specialized functions to host cells which provide versatility and adaptability for growth and survival. Plasmids which confer antibiotic resistance (R plasmids) have been extensively characterized because of their medical importance. Plasmids have played a seminal role in the spectacular advances in the area of genetic engineering. Individual genes can be inserted into specific sites on plasmids in cell cultures and the recombinant plasmid thus formed introduced into a living cell by the process of bacterial transformation. See Genetic engineering

Plasmid

a generic term for any intracellular hereditary factor that is not located within the chromosomes. Plasmids include genetic factors in cell organelles, for example, mitochondria and plastids, as well as genetic factors that are not found in any essential components of cells. Of the plasmids that are not associated with any permanent structure, the most extensively studied are the kappa-particle in paramecia (which produces the antibiotic paramecin), the sensitivity factor for CO_2, and the agent that inhibits the occurrence of male Drosophila. In addition, several bacteria possess plasmids. Bacterial plasmids control resistance to medicines and regulate the synthesis of bacteriocin, enterotoxin, hemolysin, and certain antigens. The plasmids that are called sex factors control sexual differentiation in bacteria. It has been shown that many plasmids consist of ring molecules of double-stranded deoxyribonucleic acid with a molecular weight that ranges from 10⁶ to 10⁸ daltons.

V. G. LIKHODED

plasmid

[′plaz·məd] (genetics) An extrachromosomal genetic element found among various strains of Escherichia coli and other bacteria.

plasmid

[plaz´mid] 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.conjugative plasmid a plasmid that is transferred from one bacterial cell to another during conjugation.F plasmid a conjugative plasmid found in F⁺ (male) bacterial cells that leads with high frequency to its transfer and much less often to transfer of the bacterial chromosome. A cell possessing the F plasmid (F⁺, male) can form a conjugation bridge (F pilus) to a cell lacking the F plasmid (F⁻, female), through which genetic material may pass from one cell to another.F′ plasmid a hybrid F plasmid that contains also a segment of the host chromosome.R plasmid a conjugative factor in bacterial cells that promotes resistance to agents such as antibiotics, metal ions, ultraviolet radiation, and bacteriophage.

plas·mid

(plaz'mid), A genetic particle physically separate from the chromosome of the host cell (chiefly bacterial) that can function and replicate stably and usually confer some advantage to the host cell; not essential to the cell's basic functioning. Synonym(s): extrachromosomal element, extrachromosomal genetic element, paragene [cytoplasm + -id]

plasmid

(plăz′mĭd)n. A circular, double-stranded unit of DNA that replicates within a cell independently of the chromosomal DNA. Plasmids are most often found in bacteria and are used in recombinant DNA research to transfer genes between cells.

plas·mid

(plaz'mid) A genetic particle physically separate from the chromosome of the host cell (chiefly bacterial) that can stably function and replicate; not essential to the basic functioning of the cell.
Synonym(s): extrachromosomal element, extrachromosomal genetic element. [cytoplasm + -id]

plasmid

A ring-shaped, double-stranded, piece of DNA in bacterial cells that contains genes extra to those in the chromosome. Plasmid genes code for characteristics such as toxin production and the factors that cause antibiotic resistance. Plasmids are convenient vehicles for the introduction of new genes into organisms in recombinant DNA technology (genetic engineering).

plasmid

an extrachromosomal genetic element of DNA or RNA that is capable of replicating independently of the host chromosome. Plasmids are generally circular molecules, although some linear plasmids have been found. They occur in both prokaryotic and eukaryotic cells, often in the cytoplasm. Plasmids can be important in public health since some types possess genes for antibiotic resistance, and can be quickly transferred to different types of host cell, thus spreading resistance very rapidly. Plasmids form the basis of many cloning vectors used in GENETIC ENGINEERING. See also EPISOME, CONJUGATIVE PLASMID, NON-CONJUGATIVE PLASMID.

plas·mid

(plaz'mid) Genetic particle physically separate from chromosome of host cell (chiefly bacterial), which can function and replicate stably and usually confer some advantage to the host cell. [cytoplasm + -id]

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Synonyms for plasmid

noun a small cellular inclusion consisting of a ring of DNA that is not in a chromosome but is capable of autonomous replication

Synonyms

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