Antibiotic Resistance 1

Learning Targets What strategies do bacteria use to fight streptomycin? Where do these strategies come from? 2

Antibiotic Resistance Different bacteria use different resistance strategies. Some bacteria use multiple strategies. 3 Resistance.aspx

Bacillus megaterium’s Resistance Strategies Strategy 1: Actively pump antibiotic out of cell. DNA Level: Mutation that causes over- expression of gene for pumps  more efflux pumps in cell membrane. 4 Efflux Pumps Cell Level:

Bacillus megaterium’s Resistance Strategies Strategy 2: Ribosome shape changes slightly and antibiotic can no longer bind to it. Cell Level: DNA Level: Mutation in ribosomal RNA gene 5

Summary Check Point What are the two strategies Bacillus megaterium uses to fight against antibiotics? Where did these strategies come from? 6

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Plasmids Plasmids have genes for antibiotic resistance. 9 Streptomycin Resistance Gene

Lateral Gene Transfer 10 Image Source:

Summary Plasmids reproduce and move into surrounding bacteria. Process is called lateral gene transfer. How does lateral gene transfer make antibiotic resistance an even BIGGER problem? 11

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Extra slides beyond this point 13

Natural Selection Model Over time, mutations occur in the population. Antibiotics Introduced Only resistant bacteria survive. Resistant bacteria reproduce. 14

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Natural Selection Review 16 Image Source: HealthDecide.orcahealth.com