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Temperature --> Psychorophiles
- psychorphiles: grow at cold temps, 0-15 degrees celcius
- psychotrophs: 20-30 degrees celcius
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Temperature --> mesophiles
- grow best at moderate temps, 25-40 degrees celcius
- most common type bacteria (human pahtogens)
- human body
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Temperature--> Thermophiles
- bacteria that only grows above 45 degrees celcius
- none are pahtogenic to human
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what is a minimm growth temperature?
lowest temp at which an organism grows
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what is an optimal growth temperature?
highest temp at which growth occurs
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what happens to hydrogen bonds when they are influenced by temperature?
they break and cause a different protein to make be formed.
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Most bacteria prefer what PH?
neutral PH 7.0 (6.5-7.5)
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acidophilles
grow at extremely low ph's 0-5.5
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Tell me about H. Pylori
- causes stomach ulcers
- can tolerate stomach acid, which can get as acidica s 1.0
- it burrows its way into the lining of the stomach
- produces chemical buffers
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How does osmotic pressure affect bacteria?
- exerted on them by surroundings (mainly water)
- Halophiles
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whats a halophil? (3 types)
- Obligate: require high salt concentrations to grow
- Faculative: can live w/ or w/o high salt concentrations
- Extreme: can grow in the presence of very high salt concentrations
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Carbon, Hydrogen, Oxygen is required for?
cell structure
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nitrogen is required for?
for making some bacterial amino acids and nucleic acids
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what is sulfur required for?
making some bacterial amino acids
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phosphorous is required for?
making bacterial nucleic acids, membrane phopholipid bilayer and ATP
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Potassium, Magnesium and Calcium are required for?
functioning of some bacterial enzymes
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what is iron required for?
for bacterial metabolism
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obligate aerobe?
dependent on presence of oxygen
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faculative anaerobe?
does not require oxygen but grows better in the presence of oxygen
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obligate anearobe?
dies in the presence of oxygen
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microaerophile?
requires oxygen levels between 2-10%
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aerotolerant anaerobes?
grows the same w/ or w/o oxygen
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Bacterial Growth Curve.
- lag phase: bacteria are adjusting to their enviro. & may have to synthesize enzymes to utilize the nutrients available in the enviro. little if any binary fussion occurs.
- log phase: the # of bacteria doubles and increases expotentially & will have reached the constant minimum generation. can only be sustained as long as the enviro is compatiable and has proper nutrition
- stationary phase: waster level begins to rise, nutrient level begins to fall. # cells dying= # cells divide
- death pahse: continous decline in # of dividing cells. exhaustion of nutrients & build up of toxic waste
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