microbio midterm (ch7 and 8)

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  1. Lag Phase
    • - No increase in cells
    • - May grow in size
    • - Period of unbalanced growth
    • - Proteins necessary for the uptake of available nutrients may be synthesized
    • - A period of adjustment; no cell division occurs.
  2. Exponential Growth Phase
    • - Cells are in balanced growth
    • - Each cell in the population doubles within an essentially identical unit 
    • - Important factor in rapid food spoilage on the onset of an infectious disease
    • - General time in time for doubling if the # of cells is constant.
  3. Stationary
    • - Cells continue to metabolize slowly.
    • - Some cells die and lyse when energy is exhausted.
    • - Period of survival and may mimic the condition in nature.
    • - Reproduction of cell death are exactly the same.
  4. Death Phase
    • - When culture is maintained in stationary phase beyond a certain length of time.
    • - When death phase exceeds the rate of reproduction.
  5. Calculations of microbial growth
    • No - Initial amount of bacteria.
    • t - Amount of time it was growing.
    • Nt - Amount of bacteria present at t.
    • n - Amount of generations.
    • generation time = time/generation

    • n = (logNt - logNo)/log2 
    • Nt = No * 2n

  6. Growth Measurement:Total Dry Weight
    Kept alive? Limitations, Basic method.
  7. Growth Measurement: Total Wet Weight
    Kept alive? Limitations, Basic method.
  8. Growth Measurement: Chem. Analysis of Component
     Kept alive? Limitations, Basic method.
  9. Growth Measurement: Direct Cell Count: Serial dilution
     Kept alive? Limitations, Basic method.
  10. Growth Measurement: Direct Cell Count: Concentration
    Kept alive? Limitations, Basic method.
  11. Growth Measurement: Viability Count
    Kept alive? Limitations, Basic method.
  12. Growth Measurement: Turbidity 
    Kept alive? Limitations, Basic method.
  13. Turbidity: scattered light and density
    • A= log(Io/I)
    • High absorbance readings are no longer proportional to mass because no enough light is being transmitted enough to get an accurate measurement.
  14. Synchronous Culture
    • A culture of organism where every cell in the same stage of division.
    • It is used to research bacterial cell division. It is difficult to study the cell division from one specific cell so can a synchronous culture will work. The events at the molecular level pertaining to protein synthesis, polymerization reactions, and subsequent cell assembly reactions. The sequence of events during a cell cycle can be quantitated with reasonable accuracy only when we examine a population in which all of the cells are at the same stage of division.
  15. Efficiency  
    Higher ymax  (g of cell/ mol glucose) and yatp (g of cell/ mol ATP) is more efficient.
  16. Under what conditions is cell yield proportional to nutrient concentration.
    If nutrient level is adequate.
  17. What is a microorganism growing on a liquid nutrient in a closed system under favorable conditions for a set period of time called?
    Batch culture -a nutrient liquid medium is prepared in an Erlenmeyer flask, sterilized, inoculated. The inoculated flask is then placed on a shaker (if aerobic) at appropriate growth temperature for a suitable growth period.
  18. Continuous culture
    • Dilution rate (D)
    • Volume (v)
    • Flow rate (f) - v/t
    • D= f/v
  19. Washout
    When the substrate level does not exceed the requirements for maintenance energy.
  20. Psychrophiles  
    • Bacteria that favors bellow 20 oC.
  21. Mesophiles
    Bacteria that favors between 20 oC - 44 oC
  22. Thermophiles
    Bacteria that favors 45 oC - 70 oC.
  23. Hyperthermophiles
    Bacteria that favors 70 oC to higher than 110 oC
  24. Nonhalophile
    Microbes found in freshwater that can not tolerate moderates amount of salt.
  25. Halotolerant
    Bacteria that can adapt to fresh wash and moderate amounts of salt (less than .75M NaCl )
  26. Acidophiles
    Bacteria that is lives at pH 5 or below.
  27. Neutralphiles
    Bacterial that lives at pH 5.1 - 8.9.
  28. Alkaliphiles
    Bacterial that lives at pH 9-11.
  29. Obligate aerobe
    Only grows in the presence if molecular oxygen. It has no mechanism for energy generation other than a respiratory pathway that is geared to O2 as terminal electron acceptor.
  30. Facultative aerobe
    Follows a respiratory pathway when oxygen is available, but it can employ alternate anaerobic energy-generating systems when oxygen is not available.
  31. Microaerophiles
    Organisms that occupy niches where the atmosphere has limited levels of oxygen.
  32. Obligate anaeroble
    Cannot grow in the presence of oxygen.
  33. Barophile
    Thrives at high pressure.
  34. What is the osmolarity of 4 M NaCl.
    • Osmolarity of .9% saline.
    • MW of Na = 23 g/mol
    • MW of Cl = 35.5 g/mol
    • .9gNaCl x 1 mol NaCl x 100ml
    • 100ml        58.5 g          L        = .16 M NaCl

    • .16 M NaCl x 2 = .32 Osm
    • .32(4) = 1.28 Osm
  35. Heat Sterilization - Wet
    • Conditions - Under pressure 15 Psi, 121.6 oC
    • - In an auotoclave, pV = nRT so P keeps H2O from boiling off.
  36. Heat Sterilization - Dry
    • Conditions- 160 - 180C in oven for 2-4 hours.
    • - Glassware, pippettes in cannisters wrapped in foil, protect from contamination. (Endospre contamination)
  37. Pasteurization
    • Conditions: 63 - 66 C 30 min, or 71.6 C 15s
    • - For mil/beer, doesn't sterilize.
  38. Ionizing Radiation
    • Condition: High in Gamma rays.
    • - Destructive to genetic material, free radicals (OH*) Resistance varies between species.
  39. Ultraviolet Radiation
    • Condition: Blast of ray between 220 and 320 nm.
    • - Thymine dimers, but microbes have repair mech. Must: UV damage > repair.
  40. Filter Sterilization
    • Usually room temp and pressure conditions.
    • - Glass fiber depth filters, membrane filters isospore membrane filter. The size of the spores can vary depending on the size of the bacteria.
  41. Antimicrobials
    Array of chemical agents that are used in the control of undesirable organisms. The agent will eliminate a pest without doing significant harm to other species.
  42. Antibiotics
    They are more selective in that they target a specific process of the bacteria. They can gain resistances to them.
  43. Germ-
    Involves all microbes.
  44. -static
  45. -lytic
  46. Disinfectant
    Can destroy microorganisms on contact but causes harm to host tissue.
  47. Antiseptics
    Kills or prevents growth without causing harm to host tissue.
  48. Chemotherapeutic
    A chemical compound that can be applied topically, taken orally, or injected that will inhibit or kill microbes that cause infection.
  49. MIC
    Minimum inhibitory concentration - The lowest concentration that will inhibit growth.
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microbio midterm (ch7 and 8)
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