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MCB 229 "Fundamentals of Microbiology"
Study Guide for Final Lab Quiz: Part 2 of 2


  1. What are fomites?

  2. Your skin is a not a very hospitable place for microorganisms. Why is this so?

  3. Staphylococcus aureus is a major human pathogen. What is a good test to use in order to tell the difference between S. aureus and other non-pathogenic species of Staphylococcus such as S. epidermidis?

  4. What is a streptolysin? What organism produces it? What does it do to cells?

  5. Describe the test we would perform in order to detect the presence of streptolysin.

  6. Streptococcus pyogenes is a common pathogenic organism that can be found in your throat. What disease can it cause?

  7. After streaking your blood plate agar you made a deep cut in the surface with your loop. Why did you do this?

  8. Why did we place a lit candle in the jar containing your plates and seal it before incubating it? What growth conditions did it create? What types of bacteria were you selecting for?

  9. What enzyme does Staphylococcus aureus produce that affects blood? How does it affect blood? How did you test for it?

  10. What is the difference between food poisoning and food infection?

  11. How did you test for the presence of E. coli in your food sample? Why do you need to use LT broth and an EMB plate?

  12. What are the two most common food-related pathogens?

  13. Name and describe the action of one of the exo-enzymes studied in lab.

  14. A microorganism would grow better on a starch medium if it produces which of the following enzymes?

  15. The enzyme activity that indicates the presence of cytochrome C in the organism's electron transport chain is . . . . .

  16. Describe the difference between Brownian motion and motility.

  17. Name two ways to test for bacterial motility.

  18. In the motility lab, you inoculated motility agar with certain organisms. When recording your observations, how can you determine if the organism was motile or non-motile?

  19. What minimum data must you collect for your unknown today BEFORE doing any diagnostic tests?

  20. Describe what you would see on your plates if your organism produces the indicated enzyme/exoenzyme:

  21. Upon examination of your motility agar, you notice that there is growth only along the line where you inserted the needle into the agar. Is this organism motile or non-motile?

  22. What characteristic(s) of the motility agar allows for the measurement of motility?

  23. Catalase is an enzyme which protects cells from (choose one):

  24. What is the function of the color indicator in the motility agar tubes?

  25. What are the two observations based on which you can conclude that an organism produces amylase?

  26. Pseudomonas is a strictly respiring aerobe. Describe its growth pattern in motility agar tubes.(Mention its growth pattern on the surface and inside the medium)


  27. What is the species name of the bacteria you use in the mutant hunt lab

  28. In the mutant hunt lab:
    What is the name of the mutagen that was added to its preparation?
    What does this mutagen do to the cells?

  29. In the mutant hunt lab:
    What medium is used to detect mutagenized colonies?
    What color are these colonies

  30. Which types of cells will survive to treatment with penicillin, Lac+ or Lac-? Explain why.

  31. What is the product of lacZ and its function in lactose metabolism?

  32. IF you see white colored colonies on MacConkey agar +IPTG then the mutant is: (choose one)

  33. Why IPTG is added into a MacConkey agar plate?

  34. Which gene codes for beta galactosidase and what is the function of the beta galactosidase protein?

  35. Give one objective for the mutant hunt.

  36. What color are Lac Z- colonies on:

  37. What color are Lac Y- colonies on:

  38. What are the 2 different colored colonies you expect to grow on your MacConkey lactose plates?
    What phenotypes do these colors represent?

  39. A white colony detected in your mutant hunt was transferred to a MacConkey + IPTG plate and found to produce red colonies. Was the transferred colony LacZ- or LacY-? What process allows for the formation of red colonies from a colony that is lac-?

  40. Why can't we repeat penicillin enrichments until we get all lac minus mutants?