Microbiogy test

Card Set Information

Microbiogy test
2015-09-21 23:57:50
microbiogy test week 9
Show Answers:

  1. Explain the term aseptic techniques and sterile conditions and why they are important in microbiology
    • Proper aseptic technique prevents contamination of cultures from foreign bacteria inherent in the environment.
    • thus interfering with the lab results.
    • Essential for isolation of a single species of microorganism from a mixed culture to obtain a pure culture.
    • Prevents microbes used in the laboratory from accidentally being released into the environment and/ or infecting people working in the laboratory. This is especially relevant when pathogens are being handled.
  2. Bacterial structure the gram stain is based on
    • Gram staining is based on the ability of bacteria cell wall to retaining the crystal violet dye during solvent treatment.
    • The cell walls for Gram-positive microorganisms have a higher peptidoglycan and lower lipid content than gram-negative bacteria. Bacteria cell walls are stained by the crystal violet.
    • Iodine mordant: to form the crystal violet-iodine complex so that the dye cannot be removed easily.
    • +: purple
    • -:pink
  3. three differences between gram + and gram _ bacteria
    • Gram-positive cell walls contain a thick layer of peptidoglycan that encircles the cell. Gram-negative cell walls contain a thin layer of peptidoglycan between the cytoplasmic membrane and the outer membrane.
    • -: presence of outermembrane, high lipid content
  4. key incubation conditions when culturing bacteria
    Keep plates at room temperature or incubate at 20-25 °C for 2-3 days.
  5. morphological features of bacteria seen on gram stained slide
    • spores
    • flagella
    • shape
    • arrangment