Microbiolgy Exam #2 Part 1

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Microbiolgy Exam #2 Part 1
2011-02-20 18:48:03

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  1. The complete elimination of all lifeforms, including endospores.
  2. The elimination of all vegetative cells of pathogens.
    Disinfection - does not include non-pathogenic cells
  3. The reduction of pathogens to a "safe" level.
  4. What are the substances used for cleaning microbes?
    Sterilants, Disinfectants, and Sanitizers
  5. Disinfectants that have been approved for use on the body?
  6. What is the mechanism of action?
    The specific way the methold accomplishes the killing or inhibition
  7. What are the three most common mechanisms of action?
    Damage to proteins and DNA, altering of membrane permeability, and slowing down metabolism
  8. What does damage to proteins and DNA include? What do they result in usually?
    Wet heat (denatures proteins), heavy metals (interfere with protein function), and radiation (damages DNA) - death
  9. What does altering membrane permeability include? What usually results?
    Phenolics and quaternary ammonium compounds, both of which insert themselves into the cell membrane and form hole that ruin the membrane's intergrity - damage causes them to become leaky, which causes loss of nutrients or entry of undesirable substances
  10. What does slowing down metabolism include? What does that result in?
    Bacteriostatic (slows down instead of kills) cold and desiccation (drying) - it stops reproduction
  11. Methods of controlling bacterial growth can be what?
    Physical or Chemical
  12. Physical methods of controlling bacterial growth alter what? They include what?
    Environment - the use of heat, cold, radiation, desiccation, osmotic pressure, filtration, and soaps & detergents
  13. Chemical methods of controlling bacterial growth employ what? This includes what?
    Some type of chemical attack - phenolics, halogens, alcohols, heavy metals, aldehydes, quaternary ammonium compounds, and peroxides
  14. Moist heat (hot water or steam) use what mechanism of action?
    Denatures proteins
  15. What are some methods of Moist Heat?
    Boiling, Autoclaving, and Pasteurization
  16. Endospores usually survive what type of mechanism of action?
    Boiling (especially if it is under 10 minutes)
  17. How do autoclaves work? What are they used for?
    They use steam under pressure - Used to sterilize microbiological media and medical supplies
  18. What is the most common time and temperature used in autoclaving?
    121 degrees Celsius (15 psi) for 15 minutes
  19. What is the target organism for the pasteurization of milk?
    Coxiella burnetii
  20. What are some other forms of autoclaves?
    Commerical and Home Canners (pressure cookers)
  21. What are commercial canners called? What is their canning process called?
    Retorts - Commerical Sterilization
  22. What is the target organism of commercial canning?
    Endospores of Clostridium botulinum
  23. Home canners should be operated at what temp/time?
    121 C for 15 minuts
  24. What is the most common cause of botulism?
    Inadequately processed home canned foods
  25. What is Dry Heat's mechanism of action?
    Kills by burning
  26. What is an example of Dry Heat (Fire of Hot Air)?
    incineration or hot air
  27. Dry heat is less/more effective than moist heat at the same temperatures?
  28. What is the most common time and temperature used to sterilize with hot air?
    160 degrees Celsius for 120 minutes
  29. Dry heat sterilization is usually used for what and why?
    Glass or Metal objects - high temperatures
  30. Why do some hospitals have their own incinerators?
    To burn their biological wastes
  31. What are done with the carcasses of cattle infected with anthrax?
    They are often incinerated to make sure the endospores are destroyed
  32. What is anthrax caused by?
    Bacillus anthracis
  33. What is a method of dry heat we use in lab?
    Flaming our loops (incineration)
  34. What is the mechanism of action for Cold?
    Slows Metabolism
  35. What is an example of Cold?
    Freezing and Refrigeration
  36. Cold temperatures are what to cells?
    Bacteriostatic (inhibit growth)
  37. Bacteriocidal means? Bacteriostatic?
    Kills cells, Slows them down
  38. How is the growth of most Mesophiles inhibited?
    Refrigeration temperatures
  39. What is an example of a Mesophile that its growth cannot be inhibited by refrigerator temperatures?
    Listeria monocytogenes
  40. Psychrotrophs grow at what temperatures and are responsible for what?
    Refrigeration temperatures - Refrigerated food spoilage
  41. What is the most common spoiler of raw meats?
    Pseudomonas fragi
  42. What is the mechanism of action for Radiation?
    Damages DNA
  43. What is an example of Radiatio?
    Ionizing (gamma rays, X-rays, electron beams), and non-ionizing (UV) radition
  44. Ionizing radiation is energetic enough to do what?
    Knock electrons off an atom (non-ionizing radiation is not)
  45. Gamma rays and X-rays are energetic enough for what? Useful for what?
    Pass through packaging materials - sterilizing goods after packaging (medical supplies)
  46. What is the most commonly used source of gamma rays?
  47. What is UV radiation useful for? Example?
    Surface or Air treatment - hospitals may have UV lights set up to disinfect the air
  48. What is the most effective wavelength of UV light? Why?
    260nm - DNA absorbs UV rays best at the wavelength
  49. What does UV light form? Which does what?
    Thymine Dimers - changes the shape of the DNA molecule, which causes the enzymes that make copies of DNA to malfunction
  50. The biological hood in the lab has what kind of light? Why?
    UV light - disinfect the surfaces inside the cabinet
  51. What are microwaves used for?
    Heating foods, the increase in temperature kills microbes