Genetic engineering, bacterial

The small pieces of DNA known as plasmids, which replicate independently of the chromosomes, have been discussed briefly in Chapter 5. Plasmids share a number of properties with viruses, and both are important to the techniques of contemporary molecular biology and genetic engineering. Bacterial plasmids may be present as one or several copies for each chromosome. Episomes are plasmids that are able to become integrated into the bacterial chromosome. Some extrachromosomal elements are episomes in one host and plasmids in another. Bacterial... 

One of the drawbacks of these biosensors can be the lack of selectivity as the cells and tissues contain a variety of different enzymes and thus may respond to multiple analytes simultaneously. This downside could be overcome by incubation with inhibitors or inducers that selectively cancel or select certain enzymatic functions. Another problem could be the lack of recognition element within available and practical cells or tissues to detect a certain analyte. However, with the development of recombinant methods, researchers have been able to genetically engineer bacterial cells to introduce specific enzymatic functions to an... 

Bacterial cells may harbor one or many copies of a particular plasmid, depending on the nature of the plasmid replicator. That is, plasmids are classified as high copy number or low copy number. The copy number of most genetically engineered plasmids is high (200 or so), but some are lower. 

Since 1986, the USFDA has approved 22 vaccines (Table 12.7), half of them from a genetic engineering (and all, of course, from a biotechnology source). The cells used for such genetic engineering production of vaccine can be mammalian, insect or bacterial. 

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