chapter_9_spr09 - Chapter 9 Gene Transfer, Mutations, and...

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Chapter 9 Gene Transfer, Mutations, and Genome Evolution DNA sequence is not static Horizontal gene transfer Transformation Conjugation Transduction Mutations Deletions Insertions Effects of Gene Transfer Spreads useful genes among bacteria Antibiotic-resistance genes Spread wherever antibiotics are overused Hospitals, farms Pathogenicity islands Encode genes for cell to act as pathogen Difference between typical E. coli in gut and pathogenic E. coli O157H7 Genes to degrade special metabolites (oil spills) Mechanisms of horizontal gene transfer Transformation Transduction Conjugation Transformation- competent cell picks up free DNA from the environment Some cells are naturally competent (Bacillus) Some cells can be made competent: Salt treatments _Electroporations_- electrical shock opens pores in cell membrane, DNA enters through pores. If free DNA isn’t _incorporated into chromosome, it will be degraded_. Free DNA can’t replicate on its own. Transduction – bacterial DNA is transferred from one bacterium to another by a virus _Bacteriophage_ injects DNA into host DNA is packaged into viral capsid Normally _viral___________ DNA is packaged Rarely, _bacterial_ DNA is packaged by _mistake___ DNA is transferred to new host Can bring new bacterial genes to host Generalized transduction - During viral infection, _ random pieces of bacterial DNA _are accidentally packaged into viral capsid.
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_ Any part _ of the host chromosome can be _transferred _ to a recipient cell _. Specialized transduction - only _
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chapter_9_spr09 - Chapter 9 Gene Transfer, Mutations, and...

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