This article is about the DNA molecule. For the physics phenomenon, see plasmoid.
Illustration of a bacterium showing chromosomal DNA and plasmids (Not to scale)
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria; however, plasmids are sometimes present in archaea and eukaryotic organisms.[1][2] In nature, plasmids often carry genes that benefit the survival of the organism and confer selective advantage such as antibiotic resistance. While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain only additional genes that may be useful in certain situations or conditions. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation. Synthetic plasmids are available for procurement over the internet.[3][4][5]
Plasmids are considered replicons, units of DNA capable of replicating autonomously within a suitable host. However, plasmids, like viruses, are not generally classified as life.[6] Plasmids are transmitted from one bacterium to another (even of another species) mostly through conjugation.[7] This host-to-host transfer of genetic material is one mechanism of horizontal gene transfer, and plasmids are considered part of the mobilome. Unlike viruses, which encase their genetic material in a protective protein coat called a capsid, plasmids are "naked" DNA and do not encode genes necessary to encase the genetic material for transfer to a new host; however, some classes of plasmids encode the conjugative "sex" pilus necessary for their own transfer. Plasmids vary in size from 1 to over 400 kbp,[8] and the number of identical plasmids in a single cell can range anywhere from one to thousands under some circumstances.
^Esser K, Kück U, Lang-Hinrichs C, Lemke P, Osiewacz HD, Stahl U, Tudzynski P (1986). Plasmids of Eukaryotes: fundamentals and Applications. Berlin: Springer-Verlag. ISBN 978-3-540-15798-4.
^Wickner RB, Hinnebusch A, Lambowitz AM, Gunsalus IC, Hollaender A, eds. (1987). "Mitochondrial and Chloroplast Plasmids". Extrachromosomal Elements in Lower Eukaryotes. Boston, MA: Springer US. pp. 81–146. ISBN 978-1-4684-5251-8.
^"GenBrick Gene Synthesis - Long DNA Sequences | GenScript".
^"Gene synthesis | IDT". Integrated DNA Technologies.
^"Invitrogen GeneArt Gene Synthesis".
^Sinkovics J, Horvath J, Horak A (1998). "The origin and evolution of viruses (a review)". Acta Microbiologica et Immunologica Hungarica. 45 (3–4): 349–90. PMID 9873943.
^Smillie C, Garcillán-Barcia MP, Francia MV, Rocha EP, de la Cruz F (September 2010). "Mobility of plasmids". Microbiology and Molecular Biology Reviews. 74 (3): 434–52. doi:10.1128/MMBR.00020-10. PMC 2937521. PMID 20805406.
^Thomas CM, Summers D (2008). "Bacterial Plasmids". Encyclopedia of Life Sciences. doi:10.1002/9780470015902.a0000468.pub2. ISBN 978-0-470-01617-6.
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They...
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conjugation where a conjugative plasmid present in one bacterial strain assists the transfer of a mobilizable plasmid present in a second bacterial strain...
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or mobilizable genetic element that is most often a plasmid or transposon. Most conjugative plasmids have systems ensuring that the recipient cell does...
inserted into a plasmid and that these foreign sequences would be carried into bacteria and digested as part of the plasmid. That is, these plasmids could serve...
bacterium with a conjugative plasmid (for example, the F-factor) integrated into its chromosomal DNA. The integration of the plasmid into the cell's chromosome...
peptide bonds Plasmid encode enzymes that chemically alter the drug (e.g., by acetylation or phosphorylation), thereby inactivating it. Plasmid encode beta-lactamase...
engineered plasmids. Restriction sites within an MCS are typically unique, occurring only once within a given plasmid. The purpose of an MCS in a plasmid is to...
the destination plasmid. The plasmid is often transformed into a bacterium like E. coli. Ideally when the bacterium divides the plasmid should also be...
immune response. DNA vaccines work by injecting genetically engineered plasmid containing the DNA sequence encoding the antigen(s) against which an immune...
transmission of virulence. It often involves temperate bacteriophages and plasmids. Genes responsible for antibiotic resistance in one species of bacteria...
Plant transformation vectors are plasmids that have been specifically designed to facilitate the generation of transgenic plants. The most commonly used...
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