Noun
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, to subsequent generations. In bacteria, plasmids often carry the genes for antibiotic resistance; they are exploited in genetic engineering as the vehicles for introduction of extraneous DNA into cells, to alter the genetic makeup of the cell. The cells thus altered may produce desirable proteins which are extracted and used; in the case of genetically altered plant cells, the altered cells may grow into complete plants with changed properties, as for example, increased resistance to disease.
Source: Webster's dictionaryDigital image of 3 plasmid restriction digests run on a 1% w/v agarose gel, 3 volt/cm, stained with ethidium bromide. Source: Internet
Daughter cells that retain a copy of the plasmid survive, while a daughter cell that fails to inherit the plasmid dies or suffers a reduced growth-rate because of the lingering poison from the parent cell. Source: Internet
Electroporation involves subjecting the plant or animal cell to an electric shock, which can make the cell membrane permeable to plasmid DNA. Source: Internet
An increasing number of ESBLs not of TEM or SHV lineage have recently been described. citation The ESBLs are frequently plasmid encoded. Source: Internet
Gene gun Gene gun delivery ballistically accelerates plasmid DNA (pDNA) that has been adsorbed onto gold or tungsten microparticles into the target cells, using compressed helium as an accelerant. Source: Internet
In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacteria and pelleting of the membranes (and the attached DNA). Source: Internet