Micro 233

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  1. All the bacteria cells that result from the replication of a single original bacterial organism are said to be a
    pure culture
  2. The scientist that contributed most to the development of pure culture techniques was
    Robert Koch
  3. The solidifying agent used most successfully in bacterial nutrient media is
  4. Prokaryotic cells divide by a process known as
    binary fission
  5. In nature, bacteria
    • often grow in close association with many other kinds of organisms
    • may remain in a prolonged exponential phase
    • frequently synthesize structure such as slime layers
    • may adhere to surfaces by means of pili and slime layers 
  6. Biofilms
    are polysaccharide- encased community of microorganisms, may enhance bioremediation efforts AND may protect organisms against harmful chemicals
  7. The simplest technique for isolating bacteria in growth media is referred to as the
    streak plate method
  8. Bacteria may be stored
    on a slant in the refrigerator, frozen in glycerol solution AND lypophilized.
  9. In the growth curve of a bacteria population, the bacteria are rapidly increasing in number in the
    exponential (log) phase
  10. During which phase of growth are bacteria most susceptible to antibiotics?
    exponential log
  11. When doing experiments with bacteria
    the age of the bacteria is not important
  12. During which phase of the bacteria growth curve does the total number of viable cells decline?
  13. The lag phase of the bacterial growth curved is marked by
    metabolically active cells
  14. Late log phase of the bacterial growth curve
    is marked by thee production of secondary metabolites
  15. During which phase of the bacterial growth curve does a bacterial population become much more resistant to harmful conditions
    late log phase
  16. A urine sample with more than 100,000 organisms, is considered indicative of infection. A urine sample containing 5,000 bacteria, with a generation time of 30 min sits for 3 hrs before finally being assayed. How many bacteria will then be presented within the sample?
  17. A pure culture in exponential growth phase has a bacterial concentration of 6.4 * 10^8 cell/ml if the bacterium has a generation time of 1h, How long ago was the cell concentration 8.0*10^7 cells/ml?
  18. In a rapidly multiplying bacterial population, cell numbers increase
  19. The speed of enzymatic reactions approximately doubles for each
    10 degree Celsius rise in temp
  20. Generally the proteins of thermophiles
    resist denaturation
  21. A hot tub (approx. 104 deg F or 40 deg C) would most likely contain
  22. The optimal temp. for most human pathogens might be expected to range from
    35-40 degree Celsius
  23. Bacteria on fish caught in the Artic Ocean would
    be psychrophiles AND continue to grow while the fish is in the refrigerator.
  24. Mycobacterium leprae is typically found infecting the ears, toes and fingers of its host due to its
    need for cooler temp
  25. Organisms that require gaseous oxygen for metabolism are referred to as
    obligate aerobes
  26. Which of the following is/are obligate aerobes?
    Micrococcus luteus
  27. Organisms that are indifferent to the presence of oxygen and do not use it are
    aerotolerant anaerobes
  28. The enzymes that deal with toxic oxygen - containing molecules is/are
    superoxide dismutase AND catalase
  29. Shake tubes are used to determine the
    oxygen requirements for bacterial growth
  30. The optimum pH for growth of most species of bacteria is
    pH 7
  31. High concentrations of salt and sugar in foods
    are useful in preserving the food AND tend to draw water out of a cell
  32. Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur may be considered
    major elements
  33. Trace elements
    include zinc, copper, and manganese AND may be needed for enzyme function.
  34. Small organic molecules that must be provided to bacteria in order for them to grow are called
    growth factors
  35. The prefix photo-indicates that an organism will make use of ____ for energy purposes.
  36. Organisms that use organic molecules as their source of carbon are called
  37. Organisms may derive energy from
    sunlight AND metabolizing chemical compounds
  38. Organism that use CO2 as their source of carbon are called
  39. Chemoheterotrophs
    use pre-formed organic molecules as a carbon source AND as an energy source
  40. An organism called Bacillus fastidiosus
    night be expected to be a very strict as to its growth requirements, would probably be grown on a chemically defined media AND might be expected to have a rod shape
  41. Peptone
    refers to a hydrolysate of proteins used in growth media
  42. Medically important bacteria are often
    grown on agar containing blood AND grown at 37 deg celsius
  43. Products which limit pH changes are often incorporated into media and are referred to as
  44. A medium that inhibits the growth of organisms other than the one being sought is termed a(n)
    selective medium
  45. MacConkey agar is
    a selective and differential agar
  46. Candle jars are usually used to
    provide an atmosphere with CO2
  47. In the cultivation of microaerophilic and anaerobic bacteria
    atmospheric oxygen in a(n) candle/anaerobe jar is converted to water
  48. Agar
    has chemical and physical properties that make it almost ideal for solidifying media
  49. Agar replaced gelatin as the gelling (solidifying) agent for media because
    much fewer bacteria can break down agar than gelatin AND agar is solid at body temp
  50. It is assumed that every colony observed on a streak plate arose from a single bacterium
  51. In microbiology, growth usually refers to an increase in size of the bacterium
  52. There are 5 stages of growth in an open system of culture.
  53. Secondary metabolites may be antibiotics
  54. A single bacterial cell may multiply to form a visible colony
  55. Prokaryotes are the only organisms able to use atmospheric nitrogen as a nitrogen source
  56. Freezing is an effective means of destroying bacteria
  57. One would expect most strict anaerobic organisms to have superoxide dismutase.
  58. Differential media only allows certain bacteria to grow
  59. A microbe is discovered growing hear a deep sea thermal vent when researchers bring a sample up to the surface and try to grow it in a lab at room temp. in a normal incubator, they are unsuccessful. Why?
    The pressure isnt the same at sea-level as it is on the ocean floor.
  60. You are a microbiologist working for a pharmaceutical company and discover a new secreted metabolite that can serve as a medication. Your company asks you to oversee the production of the metabolite which of the following is something that is NOT important to consider if you need to grow 5,000 liter cultures of bacteria for the purpose of harvesting the metabolite they secrete.
    The death rate of the bacteria after stationary phase is complete
  61. You are working in a clinical laboratory in a hospital setting. You're handed a throat swab from a patient. You are told specifically that the physician is only interested in what Gram positive cells are present what might you do first to go about working towards this goal? Identification isnt the main goal here just a first step to work towards determining what Gram positive cells might be there...
    Perform a Gram stain
  62. A physician send a stool sample to your lab, and wants to know if there are lactose formenting microbes in the sample. How might you determine if these microbes are present or not from this mixed-microbe specimen?
    Streak the sample for isolation on a MacConkey agar plate (which contains lactose AND a pH indicator that turns pink when acid by products are present)
  63. Your are in charge of water quality for your city's water treatment plant of the methods at your disposal, which will be the most efficient and cheapest method of determining the number of viable bacteria in the water coming out of your plant?
    Using membrane filtration followed by placing the membrane in a growth medium for colony counts after incubation
  64. You take absorbance readings on a spectrophotometer across a lehr culture of E. coli cells growing in tryptic soy broth (TSB) Your absorbance readings clearly indicate a lag phase, a log phase, and a stationary phase. You come back and take readings at 8,10,12,14+16hrs. but the absorbance number remains the same. Shouldnt it start coming down as the closed batch culture enters death phase? Whats the most likely thing that is happening?
    when we establish a growth curve, we should actually plot the log of the number of viable cells vs. time. However, a spectrophotometer can only measure absorbance. Absorbance is NOT the same as the number of viable cells. Many of the cells in the tube are most likely dead, but the machine cant discriminate between a live cell and dead one. This keeps the absorbance high even into the death phase
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Micro 233
2014-02-21 06:08:34
micro chap

Micro 233
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