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23 Cards in this Set
- Front
- Back
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Binary fission |
Prokaryotic cells divide by binary fission, this causes exponential growth: population doubles each division |
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Calculations |
N(t) = N(0) x 2^n N(t) = number of cells in population at a time N(0) = original number of cells in population N= number of divisions (total time / generational time) |
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Biofilm |
Most live in polysaccharide encased communities: biofilms Cause slipperiness of rocks in stream bed, slimy funk in sink drains, scum in toilet, dental plaque |
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Importance of biofilms |
Dental plaque leads to tooth decay, gum disease Most infectious seem to involve biofilms Industrial concerns: accumulations in pipes/drains Can foster cooperation and competition in mixed microbial communities Helpful: bioremediation, wastewater treatment |
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Lag phase |
Number of cells does not increase Cells begin synthesizing enzymes required for growth Delay depends on conditions |
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Exponential (log) phase |
Cells divide at constant rate Generation time measured in this phase Most sensitive to antibiotics |
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Stationary phase |
Nutrient levels too low to sustain growth Total numbers remain constant Some die, releasing nutrients, others grow |
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Death phase |
Total number of viable cells decreases Cells die at constant rate |
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Phase of prolonged decline |
Some fraction may survive Adapted to tolerate worsened conditions |
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Obligate aerobes |
Require 02 |
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Microaerophiles |
Require small amount of O2 only |
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Obligate anaerobes |
Cannot use O2 |
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Aerotolerant anaerobes |
Obligate fermenters (can grow in O2 but don’t use it) |
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Facultative anaerobes |
Use O2 but don’t require it |
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Photoautotrophs |
Energy from sunlight: carbon from CO2 Ex: plants, algae, Cyanobacteria |
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Photoheterotrophs |
Energy from sunlight: carbon from organic compounds Ex purple non sulfur bacteria |
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Chemolithiautotrophs |
Energy from inorganic compounds, carbon from CO2 Ex microorganisms in hot spring and hydrothermal vents |
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Chemoorganoheterotrophs |
Energy and carbon from organic compounds Ex animals, almost all human pathogens |
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Psychrophile |
-5 to 15 C |
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Psychrotroph |
20 to 30 c |
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Mesophile |
25 to 45 C |
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Thermophiles |
45 to 70 C |
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Hyperthermiphiles |
70 to 110 C |
