| R plasmid | <molecular biology> A plasmid that confers resistance to one or more antibiotics or other poisonous compounds in a bacterium. (17 Dec 1997) |
|---|---|
| plasmid | <molecular biology> A small, independently replicating, piece of extrachromosomal cytoplasmic DNA that can be transferred from one organism to another. Linear or circular DNA molecules found in both pro and eukaryotes capable of autonomous replication. Stringent plasmids occur at low copy number in cells, relaxed plasmids at high copy number, ca 10 to 30. Plasmids can become incorporated into the genome of the host or can remain independent. An example is the f factor of E. Coli. May transfer genes and plasmids carrying antibiotic resistant genes can spread this trait rapidly through the population. Described largely from bacteria and protozoa. Some plasmids are capable of integrating into the host genome. A number of artificially constructed plasmids are used as cloning vectors. (14 Oct 1997) |
| conjugative plasmid | Self-transmissible plasmid, a plasmid which encodes all the functions needed for its own intercellular transmission by conjugation. (09 Oct 1997) |
| crown gall plasmid | A plasmid, or type of circular DNA, found in the bacteria Agrobacterium tumefaciens which infects dicot plants. Part of the plasmid inserts itself into the plant genome and causes tumours to form in the roots or in the stems nearest the roots. The plasmid has been used by geneticists, minus the tumour-causing parts, as a vector towards the genetic engineering of plants. (09 Oct 1997) |
| cryptic plasmid | A plasmid which has no apparent effect on the phenotype of its host cell and has no genes other than the ones needed for itself to replicate and spread to other cells. (09 Oct 1997) |
| hybrid plasmid | <molecular biology> A plasmid (circular DNA molecule) which is composed partly of the DNA of an organisms (or virus's) genome and partly of foreign DNA that has been inserted artificially. (09 Oct 1997) |
| stringent plasmid | <molecular biology> A plasmid that only replicates along with the main bacterial chromosome and is present as a single copy, or at most several copies, per cell. (16 Dec 1997) |
| nonconjugative plasmid | A plasmid that cannot effect conjugation and self-transfer to another bacterium (bacterial strain); transfer depends upon mediation of another (and conjugative) plasmid. (05 Mar 2000) |
| supercoiled plasmid | <molecular biology> The predominant in vivo form of plasmids, in which the plasmid is coiled around histone-like proteins. Supporting proteins are stripped away during extraction from the bacterial cell, causing the plasmid molecule to supercoil around itself in vitro. (19 Jan 1998) |
| infectious plasmid | Self-transmissible plasmid, a plasmid which encodes all the functions needed for its own intercellular transmission by conjugation. (09 Oct 1997) |
| Ti plasmid | <molecular biology> Plasmid of Agrobacterium tumefaciens, transferred to higher plant cells in crown gall disease, carrying the T DNA that is incorporated into the plant cell genome. Used as a vector to introduce foreign DNA into plant cells. (18 Nov 1997) |
| transmissible plasmid | Self-transmissible plasmid, a plasmid which encodes all the functions needed for its own intercellular transmission by conjugation. (09 Oct 1997) |
| F plasmid | The prototype conjugative plasmid associated with conjugation in the K-12 strain of Escherichia coli. Synonym: F agent, F-factor, F genote, F-genote, fertility agent, fertility factor, sex factor. (05 Mar 2000) |