Review of Main Points

You are responsible for everything that we have done, everything that I have covered, and all the reading. Generally speaking, I have pulled the main points out of the reading and put them in this study guide. I estimate that if you only know this material 100%, you will get around an 80% on the exam.  We also covered many minor points which are not covered here but are in the online notes. You can count on needing to know the major points for the rest of the term including lab work & tests.  Minor points you may or may not run into again or be tested on (such as laboratory safety).  Here are the main points so far:
  1. You should know the proper Care and Use of Microscopes.
  2. You should be able to view slides under the microscope.
  3. You should be able to find your specimen and draw it under 400x magnification in 3 minutes.
  4. Know how to make and why we make Wet Mounts.
  5. Know how to properly label a Plate, a tube, or a slide.
  6. Know how to handle a plate and a tube.
  7. wk2

  8. Know how to Streak for isolation of Colonies
  9. Know some basic sterile techniques used in microbiology
  10. Know about the Ubiquity of Microbes
  11. Know what what a general purpose media is and what it is used for.
  12. Know how to read and interpret colony morphology.
  13. Know in Colony Morphology:  colony shape, margin, elevation (flat or raised or ...), texture (smooth or rough), pigmented or not, translucent or opaque. I expect you to only know intuitive terms & punctiform.
  14. wk3

  15. Know the Three Bacterial Shapes
  16. Know how to make a Bacterial Smear on a Slide, listing all the steps.
  17. Know what a simple stain is
  18. Know that there are two types of simple stains

  19. Know what is a selective media and what makes it selective
  20. Know what is a differential media and what makes it differential
  21. List the selective and differential media that we have used, listing why it is selective or differential

    Selective Media

    Differential Media


  22. Know The Gram Stain
    1. stain w/ crystal violet for 1 min
    2. wash slide w/ water
    3. fix crystal violet by adding Grams iodine for 1 min (forms a complex w/ crystal violet)
    4. wash with water
    5. decolorize by washing w/ ethanol or ethanol-acid or ethanol-acetone mixture (we used ethanol-acid)
    6. wash with water
    7. counter stain with safranin for 1-2 min
    8. wash with water

      Things that can go wrong with a Gram stain

Appearance of the Gram positive coccus and Gram negative bacillus at different stages of the gram staining procedure are illustrated on the right.
  • Gram+ cell membranes retain the crystal violet-iodine complex, so they stain purple (the safranin is masked as it is lighter in color)
  • Gram- cells loose the crystal violet-iodine complex in the decolorizing step, so they stain pink/red from safranin.
  • Why do the above occur?


  1. Differential Stains

  2. You should know how to use a pipette.

  3. Serial Dilutions (weeks 5-7)

  4. Motility in bacteria (wk5 & 7 or 8)


  5. Carbohydrate Fermentation Test or Phenol Red (PR) Broth

  6. Litmus Milk:
  7. Growth Patterns in Solid And Liquid Culture

    A number of characteristics may be observed when growing bacteria in both solid and liquid media. One may ascertain the oxygen requirements of an organism, the motility of an organism, the appearance of the growth pattern, and in some cases to some extent the chemical makeup of the cell wall. Although useful, obtaining these characteristics in this way is not always 100% reliable, at least not when trying to identify an organism.  Yet, they are useful and cheap tests for confirmation purposes of another test.

  8. The Deep Stab (Growth Patterns in Solid Culture).

    The Deep Stab is a tube filled with a medium containing agar. It is inoculated with a needle to observe the growth patterns in the agar.  The presence and location of growth in the tube then indicates the oxygen requirements for the organism.

  9. Growth in Broth (liquid) Culture.



  10. Blood Agar Plate (BAP)
  11. TSI (Triple Sugar Iron) and H2S Production