BIS+11+L+Theory+Section+Plasmids - BIS 11 L Theory Section PLASMIDS TRANSFORMATION AND ANTIBIOTICS Plasmids Extra-chromosomal DNA molecules Separate

BIS+11+L+Theory+Section+Plasmids - BIS 11 L Theory Section...

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PLASMIDS, TRANSFORMATION AND ANTIBIOTICS BIS 11 L Theory Section
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Plasmids Extra-chromosomal DNA molecules Separate from the chromosomal DNA Replicate independently from the chomosomal DNA Usually circular and double-stranded Occur naturally in bacteria Sometimes can be found in eukaryotes (example, yeast) Chromosomal DNA Plasmid DNA
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Plasmids The number of plasmids per cell (“copy number”) can vary from zero to thousands The size of plasmids can vary from 1 to 200 kilobasepairs (kbp) The ability to replicate independent of the host genome makes them like viruses However, the relationship between them and the host is more symbiotic than parasitic Allow host to survive during times of severe stress
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Terminology A plasmid that has integrated into the hosts chromosome is called an “ episome A plasmid that is used in genetic engineering is called a “ vector
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Types of Plasmids Different ways to categorize plasmids: Based on Conjugation (ability to transfer from one bacteria to another; requires tra genes) Compatibility (related plasmids are often incompatible and cannot exist in the same cell) Function
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