Microbiology 1- Techniques

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  1. How is excess fluid removed during a wet mount?
    Bibulous paper
  2. How is oil removed from the slide during a wet mount?
    Lens paper
  3. What are the steps of a methylene blue simple stain?
    • 1. Stain smear for 60 seconds using methylene blue
    • 2. Rinse off with tap water
    • 3. Blot the smear gently with bibulous paper
    • 4. Examine with microscope
  4. Why is gram-stain used?
    • Divides bacteria in 2 groups based on the structure of their cell wall
    • Gram-positive or gram-negative
  5. How does a gram-stain work?
    If cell is gram-negative, the peptidoglycan is covered by the outer membrane, so it cannot absorb the stain
  6. What are the steps of a gram-stain and the results of each step?
    • Flood the heat-fixed smear with crystal violet for 1 min- all cells turn purple
    • Add iodine solution for 1 min- all cells remain purple
    • Decolorize with alcohol for 20 sec - gram-positive cells are purple; gram-negative cells are colourless
    • Counterstain with safranin for 1-2 mins- gram positive cells are purple, gram-negative cells are pink-red
  7. What are bacterial endospores?
    • Produced by some gram-positive bacteria as a survival strategy
    • Highly resistant to adverse conditions such as extreme temperature, drying, radiations, nutrient depletion, chemicals
Card Set:
Microbiology 1- Techniques
2013-09-28 18:43:28
Microbiology Techniques

Microbiology 1- Techniques
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