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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." [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 ...
Plasmids are double-stranded extra chromosomal and generally circular DNA sequences that are capable of replication using the host cell's replication machinery. [7] Plasmid vectors minimalistically consist of an origin of replication that allows for semi-independent replication of the plasmid in the host.
3-The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell. 4-Both cells recircularize their plasmids, synthesize second strands, and reproduce pili; both cells are now viable donors. A pilus (Latin for 'hair'; pl.: pili) is a hair-like cell-surface appendage found on many bacteria and archaea. [1]
The total number of a particular plasmid within a cell is referred to as the copy number and can range from as few as two copies per cell to as many as several hundred copies per cell. [11] Circular bacterial plasmids are classified according to the special functions that the genes encoded on the plasmid provide.
An expression vector, otherwise known as an expression construct, is usually a plasmid or virus designed for gene expression in cells. The vector is used to introduce a specific gene into a target cell, and can commandeer the cell's mechanism for protein synthesis to produce the protein encoded by the gene.
1: Donor bacterium cell (F+ cell) 2: Bacterium that receives the plasmid (F- cell) 3: Plasmid that will be moved to the other bacterium 4: Pilus and T4SS. Conjugation in bacteria using a sex pilus; then the bacterium that received the plasmid can go give it to other bacteria as well. E. coli cells going through conjugation and sharing genetic ...
Other cloning vectors include the pUC series of plasmids, and a large number of different cloning plasmid vectors are available. Many plasmids have high copy numbers, for example, pUC19 has a copy number of 500-700 copies per cell, [6] and high copy number is useful as it produces greater yield of recombinant plasmid for subsequent manipulation ...
Cells that lack F plasmids are called F-negative or F-minus (F −) and as such can function as recipient cells. [citation needed] Among other genetic information, the F-plasmid carries a tra and trb locus, which together are about 33 kb long and consist of about 40 genes.