Environmental Microbiology Lecture 7 Genetic exchange in bacteria

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Environmental Microbiology Lecture 7Genetic
exchange in bacteria
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Why are bacteria so diverse?
Sexual recombination? Mutation? Gene exchange
(lateral gene transfer)?
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Mechanisms of genetic exchange in bacteria
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Transformation - free DNA is incorporated into a
recipient cell. - Griffiths experiments with
pneumococcus
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Mechanisms of transformation
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Transduction - DNA is transferred by a
bacteriophage. - Generalized transduction vs.
Specialized transduction
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Conjugation - Genetic transfer by cell to cell
contact. - F plasmid
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Genetic map of F plasmid
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Integration of F plasmid into bacterial chormosome
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(No Transcript)
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Transposons and insertion sequences
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Mechanisms of transposition
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Integrons Transposons able to capture and
express genes from other sources
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How to detect lateral gene transfer

• Incongruence between phylogenetic tree
• GC content
• Patterns of codon usage
• Insertion sequence determination

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Scope of HGT in bacterial genome