Week 4: Discussion of last week's results, Gram stains, discuss differential stains (especially capsule, acid fast, flagella)

  1. Make sure students work in groups of 4 people as much as possible. TELL THEM TO ORGANIZE THEMSELVES BEFORE THEY START WORK!!! (Saves time in the long run.)
  2. Within each group of 4:
    1. Each person should prepare and observe on a microscope a minimum of three good Gram stains. Two should be of the pure cultures and one should be from the mixed broth. Within each group, all the stock cultures (E. coli,, Staphylococcus epidermidis,and Bacillus subtilis) should be Gram stained so that every student in the group has an opportunity to observe them as well as the mixed broth.
    2. All four people are responsible for seeing the results of all the Gram stains.
    3. If people have extra time and want to, they can make and stain more smears than the ones they are required to do. In fact it is a good idea to make more smears than they expect to need, just in case the first ones don't turn out well. (Saves time later.) Please be sure that they are cleaning the slides they are finished with with Bon Ami and putting them in some consistent location so we can reuse them.
  3. Demonstrate the complete process of doing a Gram stain and explain how it works and what it is used for, at a low level. Remember, this is not 350!
  4. Remind them them to label their slides correctly, and to keep track of which side of the slide their smear is on!! (very common cause of finding smear on 10x and not on 100x/oil)

Lab orders for Week 4

Equipment:
slides, 12 working scopes, loops, immersion oil, lens paper, bibulous paper, Gram stain reagents (Check iodine to make sure it is fresh enough to work well.)
Cultures:
for class (per group):
Media:
none