Micro Baterial Morphology Lab

Bacterial Morphology

Part 1: Viewing Prepared Slides of Common Bacterial Shapes

Familiarize yourself with each morphological type to use as a comparative tool for the remainder of the activity. Record your observations.

Part 2: Disinfecting Your Area to Use Live Organisms:

Part 3: Viewing Live Organisms – Wet Mount Preparation

There was several amoeba shaped cells that varied in size. There were five somewhat darker areas that were circular in shape. There were also three large, oddly shaped areas that had very distinct edges.

Part 4: Direct Staining:

Slide One: There were two clusters that were fairly easy to recognize. All of the cells were cocci. Some of the cells were large while others were practically nonexistent.

Slide Two: There were different layers of cells. The cells were rectangular in shape and varied in size. A nucleus was visible in each cell.

Slide Three: This slide was a mixture of different shapes. Nothing was recognizable.

Part 5: Indirect Staining:

Chains of both cocci and bracillus cells were both visible and identifiable. The chains varied in length. The cheek and yeast smear was clearer. The same shapes were seen as before just with sharper outlines. The cells were much easier to see with more detail.

Questions:

A. What are the advantages of using bleach as a disinfectant? The disadvantages? The advantages of using 70% alcohol? The disadvantages?

B. List three reasons why you might choose to stain a particular slide rather than view it as a wet mount.

C. Define the following terms:

• Chromophore:
• Acidic Dye:
• Basic Dye:

D. What is the difference between direct and indirect staining?

E. What is heat fixing?
F. Why is it necessary to ensure that your specimens are completely air dried prior to heat fixing?
G. Describe what you observed in your plaque smear wet mount, direct stained slide, and indirectly stained slide. What were the similarities? What were the