micro exam #2

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micro exam #2
2011-02-23 01:30:10

micro exam #2
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  1. Temperature --> Psychorophiles
    • psychorphiles: grow at cold temps, 0-15 degrees celcius
    • psychotrophs: 20-30 degrees celcius
  2. Temperature --> mesophiles
    • grow best at moderate temps, 25-40 degrees celcius
    • most common type bacteria (human pahtogens)
    • human body
  3. Temperature--> Thermophiles
    • bacteria that only grows above 45 degrees celcius
    • none are pahtogenic to human
  4. what is a minimm growth temperature?
    lowest temp at which an organism grows
  5. what is an optimal growth temperature?
    highest temp at which growth occurs
  6. what happens to hydrogen bonds when they are influenced by temperature?
    they break and cause a different protein to make be formed.
  7. Most bacteria prefer what PH?
    neutral PH 7.0 (6.5-7.5)
  8. acidophilles
    grow at extremely low ph's 0-5.5
  9. neutrophil
  10. alkalophil
  11. 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
  12. How does osmotic pressure affect bacteria?
    • exerted on them by surroundings (mainly water)
    • Halophiles
  13. 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
  14. Carbon, Hydrogen, Oxygen is required for?
    cell structure
  15. nitrogen is required for?
    for making some bacterial amino acids and nucleic acids
  16. what is sulfur required for?
    making some bacterial amino acids
  17. phosphorous is required for?
    making bacterial nucleic acids, membrane phopholipid bilayer and ATP
  18. Potassium, Magnesium and Calcium are required for?
    functioning of some bacterial enzymes
  19. what is iron required for?
    for bacterial metabolism
  20. obligate aerobe?
    dependent on presence of oxygen
  21. faculative anaerobe?
    does not require oxygen but grows better in the presence of oxygen
  22. obligate anearobe?
    dies in the presence of oxygen
  23. microaerophile?
    requires oxygen levels between 2-10%
  24. aerotolerant anaerobes?
    grows the same w/ or w/o oxygen
  25. 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