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2011-05-23 19:18:04
Microbial Nutrition Culturing

CH 12: Microbial Nutrition and Culturing
Show Answers:

  1. What are the 6 most abundant elements in microbes:
    • 1. Carbon
    • 2. Oxygen
    • 3. Nitrogen
    • 4. Hydrogen
    • 5. Phosphorus
    • 6. sulfur
  2. What are the 6 most abundant types of molecules in living bacterium:
    • 1. Water
    • 2. Proteins
    • 3. RNA
    • 4. Carbohydrates
    • 5. Lipids
    • 6. DNA
  3. The most abundant component of living bacteria:
    - Water
  4. Autotrophs:
    Bacteria that can use CO2 from air as carbon source.
  5. Heterotrophs:
    Bacteria that require their carbon source in an organic form eg., sugar or amino acid
  6. Fastidious organisms:
    Bacteria that do not produce their own vitamins, usually because they can acquire them from the host.
  7. Auxotrophs:
    Mutant bacteria that are incapable of synthesizing an organic molecule, such as a vitamin.
  8. Photoautotrophs:
    Bacteria that derive energy from light
  9. Halophiles:
    Bacteria that have adapted to growth in high salt conditions.
  10. Methanogens:
    Bacteria that derive energy from CO2 and H to produce methane gas
  11. Chemoautotrophs:
    Bacteria that derive energy from rocks or nimerals rather than sunlight or organic materials
  12. How are culture media produced:
    Agar is added to the cx broth, the entire mix is boiled to melt agar, and the mix is poured into petri dishes where it solidifies as it cools to room temp.
  13. distinguish defined media from complex media:
    - The complete chemical contents are known in defined media.

    - Complex media includes some component that is from a biological source, animal or plant, in which some of the chemicals are not know.
  14. Selective media:
    - Allow some organisms to grow while inhibiting others.
  15. Differential media:
    - Allow several kinds of organisms to grow, but they appear differently, ie. organism appear as different colors.
  16. How are pure bacterial cultures obtained:
    - Streaking a sample of bacteria onto a petri dish so that individual bacteria fall in well-isolated positions. The bacteria are grown into colonies so that individual colonies can be recovered as pure cultures.
  17. Name and define the technique used to work w/microbial cultures:
    - Aseptic technique is used to work with microbial cx.

    - handling samples so that they do not become contaminated from outside sources.
  18. How does diffusion assist a cell nutritionally:
    - Because of Brownian motion, nutrient molicules are constantly moving, so they make contact w/bacterium, pass through outer layers, and diffuse to bacteria's cytoplasmic membrane where the cell can transport them inside.

    - The movement of atoms or molecules from an area of higher concentration to an area of lower concentration

    -Osmosis: going from lower to higher solute concentration
  19. What prevents a bacterial cell from rupturing due to internal osmotic or hydrostatic pressure:
    - Hydrostatic pressure: The strength of the peptidoglycan layer prevents a bacterial cell from rupturing due to internal osmotic or hydrostatic pressure.
  20. Aerobes:
    - Bacteria that grownin the presence of oxygen
  21. Facultative anaerobes:
    - Bacteria that grow w/ or w/o oxygen
  22. Macroaerophiles:
    - Bacteria that require reduced levels of oxygen
  23. Anaerobes:
    - Bacteria that fail to grow in presence of O2.
  24. Acidophiles:
    - Bacteria that grow in acidic environments.
  25. Alkalaphiles:
    - Bacteria that grown in alkaline environments.
  26. Obligate halophiles:
    - Bacteria that cannot grow w/o salt.
  27. Psychrophiles:
    - Bacteria that thrive in cold temp
  28. Mesophiles:
    - Bacteria that thrive in warm temp
  29. Thermophiles:
    Bacteria that thrive in hot temp.
  30. Thermoduric bacteria:
    - Bacteria that cannot grow in high temp, but are also not killed by high temp
  31. Symbiosis:
    - A relationship where diff organisms grow w/one another.
  32. Synergism:
    - A relationship in which the total growth of 2 or more organisms is more than would have resulted had they grown independently.
  33. Commensalism:
    - A relationship in which one organism helps another but is unaffected itself.
  34. Antagonism:
    - A harmful relationship between two organisms
  35. Normal flora:
    - The native microbes that an individual harburs w/o causing disease.