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40 Cards in this Set
- Front
- Back
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BINARY FISSION
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-asexual reproduction
-genetically identical offspring -allows for exponential growth |
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Generation (doubling time)
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-the amount of time it takes bacteria every time it divides and reproduces
-varies from species to species |
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BIOFILM and its importance
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-polymer encased microbial community
-bacteria grows on a surface -sense and responds to environmental change, interacts with organisms in complex communities |
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PURE CULTURE
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-single species from once cell
-used in laboratories -can behave differently than in natural habitat -only 1% have been cultured |
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Bacterial Growth Curve
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-applies to liquid cultures
-lag phase -exponential (log) phase -stationary phase -death phase -phase of prolonged decline |
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Lag Phase
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-not much growth
-starting, small population -building macromolecules needed to produce more -length depends on starting pop & richness of nutrients |
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Exponential (log) Phase
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-population doubles every generation
-synthesis of 1* metabolites (required for growth) |
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Stationary Phase
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-growth is 0
-# new cells = # of dying cells - 2* metabolites (toxins, etc) |
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Death Phase
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-# new cells < # dying cells
-fairly constant rate of decline |
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Phase of Prolonged Decline
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-remaining bacteria are the most "fit"
-quick evolution of population |
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What is optimal growth temperature?
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-temperature at which organism multiplies most rapidly
-enzymes determine optimal temp |
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Does freezing or chilling food kill most bacteria? Why?
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-No
-Enzymes work better at higher temperatures -cold slows them down -membrane gels, growth slows or doesn't occur |
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Does high heat kill most bacteria? Why?
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-yes
-high heat denatures the enzymes -causes cell to collapse, thermal lysis |
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PSYCHROPHILES
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-cold lovers
-10*C |
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PSYCHROTROPHS
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-can grow in cold
-25*C, room temp |
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MESOPHILES
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-warm lovers
-37*C, body temp |
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THERMOPHILES
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-heat lovers
-60-70*C |
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HYPERTHERMOPHILES
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-really heat lovers
-90-100*C -very resistant to denaturing |
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How do prokaryotes survive in extreme pH environments?
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-enzymes adapted to survive
-can control # p+ in cells |
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How do some bacteria prevent plasmolysis in hypertonic environments?
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-pump ions so cell concentration is similar to environment, prevent osmosis
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How can oxygen be toxic to a cell?
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-oxygen oxidizes cells, takes e-
-anaerobic microbes cannot produce enzymes to protect from oxidation -(superoxide dismutase, catalase) |
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Describe the roles of superoxide dismutase and catalase in oxygen utilization and/or intolerance
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-protection from oxidation if have enzymes
-superoxide dismutase catalyzes superoxide into hydrogen peroxide and oxygen -catalase breaks hydrogen peroxide into water and oxygen |
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Obligate aerobes
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-need oxygen to survive
-& to produce energy in ETC -have both enzymes |
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Obligate anaerobes
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-No oxygen, anaerobic respiration
-DON'T have the enzymes |
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Facultative anaerobes
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-can live w/out oxygen by doing fermentation
-prefers oxygen -have both enzymes |
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Microaerophile
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-small amount of oxygen (2-10%)
-produces catalase sometimes -cant survive in too little or too much oxygen |
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Aerotolerant aerophiles
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-(obligate fermenters)
-only do fermentation -can survive in oxygen |
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Neutrophiles
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- pH 5-8 (body pH)
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acidophiles
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- pH <5
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alkalophiles
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- pH > 8
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facultative
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-optional
-can have, but not neccesary |
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Obligate
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-need to survive
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Major nutritional modes
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photoautotrophs- photosynthesis
photoheterotrophs- only prokaryotes chemoautotrophs- only prokaryotes chemoheterotrophs- us |
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sterilization
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-highest level of bacterial control
-kill all microorganisms, bacteria, viruses, endospores -heat, chemicals, irradiation, filtration |
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Disinfection
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-gets rid of things that cause pathogens, things that cause disease
-disinfectant- surfaces ex. bleach, lysol -antiseptic- skin ex. hydrogen peroxide, isopropyl alcohol |
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Pasteurization
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-brief heat treatment
-reduce bacteria that would spoil food or containers |
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Physical methods of microbial growth control and applications
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HEAT
*moist- boiling- low tech inexpensive destroys most organisms and viruses, doesn't destroy endospores -pasteurization- significant reduces organisms, increase shelf life -pressurized steam- autoclave *Dry- not as effective, requires longer times and higher temps-incineration- burning -membrane filtration- fine filter traps bacteria and viruses liquid or air -radiation- zap w/ UV light- used for food ionizing or non -pressure- denatures proteins, uses less heat |
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Chemical methods of microbial growth control and applications
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-(antiseptics/disinfectants)
-germicidal chemicals -reacts with vital cell sites -liquids- alcohol -gas- ozone |
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Describe how food products and other products can be preserved by preventing the growth of microbes
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-breads, cheeses, juices preserved by adding weak organic acids
-meats processed with nitrite or nitrate inhibit growth of endospores -refrigeration inhibits growth by slowing or stopping enzyme reaction -freezing stops microbial growth but some can survive and spoil once thawed -salting and drying decreases availability of water in food below limits required for growth of most microbes, high concentration causes plasmolysis -adding salt or sugar dehydrates cells |
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plasmolysis
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shrinking of the cytoplasm of a plant cell due to the diffusion of water out of the cell into a hypertonic solution
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