Lab Quiz 1

  1. pure culture
    one in which all organisms are descendants of the same organism
  2. sterile medium
    free of all life forms
  3. inoculum
    growing organisms to be transferred
  4. asceptic technique
    method of preventing unwanted microorganisms from gaining access
  5. colony
    • visible mass of microorganisms growing on an agar surface
    • usually originating from single organism or arrang. of organisms
  6. three types of growth in broth culture:
    • pellicle - mass floating at the top
    • turbidity - general cloudiness throughout
    • sediment - mass deposited at the bottom
  7. obligate aerobe
    grow only in the presence of oxygen
  8. microaerophiles
    require low conc. of oxygen to grow
  9. obligate anaerobes
    grow only without oxygen
  10. aerotolerant anaerobes
    cannot use oxygen but tolerate it fairly well
  11. facultative anaerobes
    grow with or without oxygen
  12. psychrophiles
    • cold loving bacteria
    • -5C to 15C
  13. mesophiles
    • grow best at moderate temps
    • 25C to 45C
  14. thermophiles
    • heat loving bacteria
    • 45C to 70C
  15. hyperthermophiles
    • very high temps
    • 70C to 110C
  16. chromogenic
    produce pigment during growth
  17. water-soluble pigment
    diffuses out of the organism and onto surrounding medium
  18. water-insoluble pigment
    does not diffuse out of organism
  19. state three basic shapes of bacteria.
    bacillus, coccus, spiral
  20. state and describe five different arrangements of cocci.
    diplococcus, streptococcus, tetrad, sarcina, staphylococcus
  21. state and describe three different arrangements of bacilli.
    bacillus, streptobacillus, coccobacillus
  22. state and describe three different spiral forms.
    vibrio, spirillum, spirochete
  23. describe the appearance of a typical yeast.
    • beaded appearance
    • reproduce by budding
  24. Define selective medium
    inhibits growth of one group of organisms while permitting the growth of another
  25. Define differential medium
    • contains additives that cause an observable color change in the medium when a particular chemical reaction occurs
    • this indicates whether or not the organism can carry out a specific biochemmical reaction
  26. Define enrichment medium
    • enhances the growth of certain organisms
    • useful when you have a small number of an organism and want to grow a lot more
  27. Define combination selective-differential medium
    permits the growth of one group or organisms while inhibiting the growth of another AND differentiates those organisms that grow based on whether they can carry out particular chemical reactions
  28. State the usefulness of Columbia CNA agar and MacConkey Agar
    • Columbia CNA - selective for gram-positive bacteria, inhibits growth of gram-negative
    • MacConkey - selective for gram-negative and lactose fermentation
  29. Describe how E. coli appears on MacConkey agar
    appears bright pink to red, surrounded by a pink halo
  30. Describe how Enterobacter aerogenes would appear on MacConkey agar
    appear bright pink to red, not surrounded by a pink halo
  31. Describe how Salmonella would appear on MacConkey agar
    colorless colonies
  32. Formula for determining the number of CFUs per ml of sample when using plate count technique
    number of colonies x dilution factor
  33. State the principle behind the direct microscopic method of enumeration
    the # of bacteria in a small known volume is directly counted microscopically and the # of bacteria in the larger original sample is extrapolated
  34. State the formula for determining the number of bacteria per cc of sample when microscopic method of enumeration
    average # of bacteria per large double-lined square x dilution factor of the large square x dilution factor of dilutions
  35. State the function of a spectrophotometer
    used to measure turbidity
  36. State the relationship between absorbance (optical density) and the # of bacteria in a broth sample
    • the absorbance is directly proportional to the cell concentration
    • the greater the # of bacteria, the higher the absorbance
  37. State the relationship between percent light transmitted and the number of bacteria in a broth sample
    • the percent of light transmitted is inversely proportional to the bacterial concentration
    • the greater the number of bacteria, the lower the percent light transmitted
  38. Define genus and species
    • genus = first name
    • species = second name
  39. State the length and width of an average rod-shaped/bacillus bacterium
  40. State the diameter of an average coccus-shaped bacterium in micrometers
  41. Define ocular lens
    • aka eyepiece
    • magnifies 10x
  42. Define objective lens
    • mounted on turret near stage
    • yellow, blue, and white
  43. State the reason for using immersion oil at 100x
    the immersion oil traps the light and prevents the distortion effect that is seen as a result of the bending of the light waves
Card Set
Lab Quiz 1
Lab Quiz 1: intro + labs 1-4