BIOS 242-Study Guide - Practical
1. Identify parts and functions of of microscope- coarse and fine focus. Stage, optical
lens, illuminator, neck, base.
Answer:
2. Calculate final power of magnification.
Multiply your magnification by 100.
3. Identify nutrient agar, slants, broth, plate.
Nutrient agar is a general-purpose medium supporting growth of a wide range of non-fastidious
organisms. It typically contains (mass/volume): 0.5% Peptone. 0.3% beef extract / yeast extract.
4. Identify Gram positive or Negative?
Gram Positive- bacteria that retain the crystal violet dye do so because of a thick layer of
peptidoglycan
Gram Negative- do not retain the violet dye and are colored red or pink
5. Morphology of the bacteria-. Cocci, Bacillus, Spiral, Pleomorphic
Cocci- Spherical shape
Bacillus- rod-shaped
, Spiral- 1) vibro is curved or comma shaped rod. 2)spirillum is a thick rigid spiral. 3)spirochete is
a thin flexible spiral. Bacteria with a spiral shape is called spirillum.
Pleomorphic- is the ability of some bacteria to alter their shape or size in response to
environmental conditions
6. Cellular arrangement- Streptococci, Streptobacilli, Staphylococci, Staphylobacilli
Streptococcus is a genus of coccus Gram-positive bacteria belonging to the phylum Firmicutes
and the order Lactobacillales.
Streptobacillus is a genus of aerobic, gram-negative facultative anaerobe bacteria, which grow
in culture as rods in chains.
Staphylococcus is a genus of Gram-positive bacteria. Under the microscope, they appear round,
and form in grape-like clusters
Streptobacillus is a genus of aerobic, gram-negative facultative anaerobe bacteria, which grow
in culture as rods in chains.
7. Identify special staining and organism- Acid fast (Mycobacterium), Capsule (Klebsiella),
flagella (E.coli).
8. Kirby Bauer or disk diffusion experiment, zone of inhibition.
Kirby-Bauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid
growth media surrounding sources of drug.
9. Steps of Gram staining and how will Gram positive and negative bacteria appear after
each step.
1. Application of the primary stain Crystal Violet (CV) to a heat-fixed smear of bacterial culture.
2. Addition of Gram’s Iodine.
3. Decolorization with 95% ethyl alcohol.
4. Counterstain with Safranin
10. Decolorizing agent in Gram staining.
The decolorizing agent serves two main functions. The first is as a lipid solvent for gram-
negative cells. This alcohol will dissolve the outer lipid layers of the cell wall which will
ultimately result in these cells appearing colorless. The second function is as a protein-
dehydrating agent in gram-positive cells.
11. Catalase test identifies? Which organism is positive
1. Identify parts and functions of of microscope- coarse and fine focus. Stage, optical
lens, illuminator, neck, base.
Answer:
2. Calculate final power of magnification.
Multiply your magnification by 100.
3. Identify nutrient agar, slants, broth, plate.
Nutrient agar is a general-purpose medium supporting growth of a wide range of non-fastidious
organisms. It typically contains (mass/volume): 0.5% Peptone. 0.3% beef extract / yeast extract.
4. Identify Gram positive or Negative?
Gram Positive- bacteria that retain the crystal violet dye do so because of a thick layer of
peptidoglycan
Gram Negative- do not retain the violet dye and are colored red or pink
5. Morphology of the bacteria-. Cocci, Bacillus, Spiral, Pleomorphic
Cocci- Spherical shape
Bacillus- rod-shaped
, Spiral- 1) vibro is curved or comma shaped rod. 2)spirillum is a thick rigid spiral. 3)spirochete is
a thin flexible spiral. Bacteria with a spiral shape is called spirillum.
Pleomorphic- is the ability of some bacteria to alter their shape or size in response to
environmental conditions
6. Cellular arrangement- Streptococci, Streptobacilli, Staphylococci, Staphylobacilli
Streptococcus is a genus of coccus Gram-positive bacteria belonging to the phylum Firmicutes
and the order Lactobacillales.
Streptobacillus is a genus of aerobic, gram-negative facultative anaerobe bacteria, which grow
in culture as rods in chains.
Staphylococcus is a genus of Gram-positive bacteria. Under the microscope, they appear round,
and form in grape-like clusters
Streptobacillus is a genus of aerobic, gram-negative facultative anaerobe bacteria, which grow
in culture as rods in chains.
7. Identify special staining and organism- Acid fast (Mycobacterium), Capsule (Klebsiella),
flagella (E.coli).
8. Kirby Bauer or disk diffusion experiment, zone of inhibition.
Kirby-Bauer testing measures sensitivity of bacteria to antibiotics by culturing bacteria on solid
growth media surrounding sources of drug.
9. Steps of Gram staining and how will Gram positive and negative bacteria appear after
each step.
1. Application of the primary stain Crystal Violet (CV) to a heat-fixed smear of bacterial culture.
2. Addition of Gram’s Iodine.
3. Decolorization with 95% ethyl alcohol.
4. Counterstain with Safranin
10. Decolorizing agent in Gram staining.
The decolorizing agent serves two main functions. The first is as a lipid solvent for gram-
negative cells. This alcohol will dissolve the outer lipid layers of the cell wall which will
ultimately result in these cells appearing colorless. The second function is as a protein-
dehydrating agent in gram-positive cells.
11. Catalase test identifies? Which organism is positive
