MICRO CH9

MICRO CH9 - Chapter 9 Gene Transfer, Mutations, and Genome...

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Chapter 9 Gene Transfer, Mutations, and Genome Evolution DNA sequence is not static Horizontal gene transfer Transformation: Conjugation Transduction Mutations: occur in the organism genome, causes change over time. Ex) chemical, UV radiation Deletions: can be one nitrogen base or a whole section Insertions: additional information 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 ex) gene for virulent factors Difference between typical E. Coli in gut and pathogenic E.Coli 0157:H7, this one has a pathogenicitic island Genes to degrade special metabolites (oil spills) Some bacteria have genes have things to break down oil and it’s a nutrient for them. Mechanisms of horizontal gene transfer Transformation Transduction Conjugation Transformation- competent (able to) cell picks up free DNA from the environment. When cells die, they lyse open and their DNA is open up and it is now free DNA.
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Some cells are naturally competent (Bacillus) Some cells can be made competent: Salt treatments (treat with different salts will neutralize the different salts in the DNA and it will make it more likely to get the salts into the cell) Electroporation: 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 it’s own. Transduction – bacterial DNA is transferred from one bacterium to another by a virus (accident that occurs when new virus is being made and puts bacterial DNA into cell instead of viral DNA) 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. Any part
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MICRO CH9 - Chapter 9 Gene Transfer, Mutations, and Genome...

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