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A transformation efficiency of 1×10 8 cfu/μg for a small plasmid like pUC19 is roughly equivalent to 1 in 2000 molecules of the plasmid used being introduced into cells. In E. coli , the theoretical limit of transformation efficiency for most commonly used plasmids would be over 1×10 11 cfu/μg.
A pUC19 cloning vector showing the multiple cloning site sequence with restriction enzyme sites. A multiple cloning site (MCS), also called a polylinker, is a short segment of DNA which contains many (up to ~20) restriction sites—a standard feature of engineered plasmids. [1]
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]
For example, pBR322 is a medium copy number plasmid (~20 copies/cell) from which several high copy number cloning vectors (>100 copies/cell) have been derived by mutagenesis, such as the well known pUC series. [1] This delivers the convenience of high plasmid DNA yields but the additional burden of the high copy number restricts the plasmid size.
The term plasmid was coined in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." [11] [12] 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 ...
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 ...
Plasmid sizes vary from 1 to over 1,000 kbp. I doubt that there are any plasmids smaller than roughly 500 bp. Plasmids vary in size; the smallest plasmid is only 846 bp long and contains only one gene. [1] Markus29 13:37, 6 February 2013 (UTC)
The most common method is alkaline lysis, which involves the use of a high concentration of a basic solution, such as sodium hydroxide, to lyse the bacterial cells. [15] [16] [17] When bacteria are lysed under alkaline conditions (pH 12.0–12.5) both chromosomal DNA and protein are denatured; the plasmid DNA however, remains stable.