lecture 10 - Plasmids chromosome Extrachromosomal DNA,...

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Plasmids • Extrachromosomal DNA, usually circular • Has its own origin of replication – Usually do not code for essential proteins – Important for bacteria to adapt to the changing environments (e.g. antibiotic treatments) •S i z e v a r i e s : several kilobase (Kb) to megabase (Mb) • Copy number varies : 1 to several hundred per cell • Plasmid Curing : loss of plasmids from bacteria without the selective pressure – Media without antibiotics can cure resistant plasmids – Rich media can cure catabolic plasmids • Transferred by transformation and conjugation chromosome
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• Origin of replication • Antibiotic resistance genes • Dependent on the host bacterial machinery to replicate and produce protein products. • Very active – flexible genome
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Plasmid Replication • Bidirectional replication – Similar to chromosomal replication • Unidirectional (“ rolling circle ”) replication – Starts at a nick – Provides 3 -OH for synthesizing a new plus strand – The old plus strand is used as the template to synthesize the new minus strand
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Microbial Genetics Nucleic acid – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) Central dogma – DNA replication – Transcription – Translation DNA RNA Protein
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This note was uploaded on 01/31/2011 for the course BIO 121 taught by Professor Ma during the Winter '10 term at UC Riverside.

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lecture 10 - Plasmids chromosome Extrachromosomal DNA,...

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