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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 ...
In molecular biology, a cryptic plasmid is a plasmid that doesn't appear to provide any clear advantage to its host, yet still persists in bacterial populations. [1] These plasmids appear to lack any genetic functions of interest and do not seem to contain genes that could provide beneficial functions to their hosts.
Plasmids with specially-constructed features are commonly used in laboratory for cloning purposes. These plasmid are generally non-conjugative but may have many more features, notably a " multiple cloning site " where multiple restriction enzyme cleavage sites allow for the insertion of a transgene insert.
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 ...
Molecular cloning takes advantage of the fact that the chemical structure of DNA is fundamentally the same in all living organisms. Therefore, if any segment of DNA from any organism is inserted into a DNA segment containing the molecular sequences required for DNA replication, and the resulting recombinant DNA is introduced into the organism from which the replication sequences were obtained ...
An example of a plasmid cloning vector which modifies the inserted protein is pFUSE-Fc plasmid. In order to genetically engineer insulin, the first step is to cut the MCS in the plasmid being used. [7] Once the MCS is cut, the gene for human insulin can be added making the plasmid genetically modified.
Medium copy number plasmids, also called relaxed plasmids, require a system to ensure that replication is inhibited once the number of plasmids in the cell reaches a certain threshold. Relaxed plasmids are generally regulated through one of two mechanisms: antisense RNA or iteron binding groups. Low copy number plasmids, also called stringent ...
Shuttle vectors include plasmids that can propagate in eukaryotes and prokaryotes (e.g. both Saccharomyces cerevisiae and Escherichia coli) or in different species of bacteria (e.g. both E. coli and Rhodococcus erythropolis). There are also adenovirus shuttle vectors, which can propagate in E. coli and mammals.