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The term plasmid was coined in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." [14] [15] The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time ...
pBR322 is a plasmid and was one of the first widely used E. coli cloning vectors. Created in 1977 in the laboratory of Herbert Boyer at the University of California, San Francisco, it was named after Francisco Bolivar Zapata, the postdoctoral researcher and Raymond L. Rodriguez. The p stands for "plasmid," and BR for "Bolivar" and "Rodriguez."
The F factor was the first plasmid to be discovered. Unlike other plasmids, F factor is constitutive for transfer proteins due to a mutation in the gene finO. [4] The F plasmid belongs to F-like plasmids, a class of conjugative plasmids that control sexual functions of bacteria with a fertility inhibition (Fin) system. [5]
They are the standard cloning vectors and the ones most commonly used. Most general plasmids may be used to clone DNA inserts of up to 15 kb in size. One of the earliest commonly used cloning vectors is the pBR322 plasmid. Other cloning vectors include the pUC series of plasmids, and a large number of different cloning plasmid vectors are ...
Cells which have been successfully transformed with pUC19 can be differentiated from cells which have not by growing them on media with ampicillin. Only the cells with the plasmid containing amp R will survive. The origin of replication (ori), is derived from the plasmid pMB1. [6] [1] pUC19 is a high copy number plasmid. [3]
conjugative - mediate DNA transfer through conjugation and therefore spread rapidly among the bacterial cells of a population; e.g., F plasmid, many R and some col plasmids. nonconjugative - do not mediate DNA through conjugation, e.g., many R and col plasmids. The pBR322 plasmid is one of the first plasmids widely used as a cloning vector.
The structure of the Ti plasmid. A tumour inducing (Ti) plasmid is a plasmid found in pathogenic species of Agrobacterium, including A. tumefaciens, A. rhizogenes, A. rubi and A. vitis. Evolutionarily, the Ti plasmid is part of a family of plasmids carried by many species of Alphaproteobacteria.
Iterons have an important role in plasmid replication. An iteron-containing plasmid origin of replication can be found containing about five iterons about 20 base pairs in length total. These iterons provide a saturation site for initiator receptor proteins and promote replication, thus increasing plasmid copy number in a given cell. [1]