The la b pra ctica l is worth 50 points, or roughly 25% of your fina l la b gra de.
Study Guide:
1. M icroscope (UN IT 1)
a. What is the magnification of the ocular lens?
b. How do you calculate total magnification?
2. Gra m Sta in (UN IT 4)
a. What is the difference in the cell wall composition of Gram-negative vs. Gram-positive bacteria?
b. How is the cell wall composition affected by the decolorizer?
c. What colors will Gram-negative and Gram-positive bacteria be after the Gram stain?
i. Gram-negative: __________ ii. Gram-positive: __________
d. What dyes produce each color?
3. Selective a nd Differentia l M edia (UN IT 5) a . M SA
i. What is the nutrient in MSA that the bacteria ferments?
ii. Which bacteria are selected for when using an MSA plate? 1. Are they Gram-positive or negative?
2. If a bacteria grows on MSA, it must be able to tolerate______.
iii. What do the following results mean?
1. Bacteria grows and turns the media yellow.
2. Bacteria grows but media stays light pink
3. Bacteria does not grow.
b. M a cConkey
i. What is the nutrient in the MacConkey plate that the bacteria metabolizes?
ii. Which bacteria are selected for when using a MacConkey Plate? 1. Are they Gram-positive or Gram-negative?
iii. What do the following results mean? 1. Media turns purple-red.
2. Media turns light pink.
3. Bacteria grows but there is no color change of the media.
4. Bacteria does not grow.
c. E M B
i. What is the nutrient in the EMB plate that the bacteria metabolizes?
ii. Which bacteria are selected for when using an EMB Plate? • Are they Gram-positive or Gram-negative?
iii. What do the following results mean?
1. Media turns purple.
2. Media turns metallic green.
3. Bacteria grows but there is no color or it is pale lavender.
4. Bacteria does not grow.
d. CN A
i. What is the source of nutrition in a CNA plate?
1. How can you tell if the nutrient has been digested?
2. What is the name of this process?
ii. Which bacteria, Gram-negative or Gram-positive cannot grow on CNA?
• What chemical inhibits them?
iii. What do what results do the following types of hemolysis produce? Is it complete, incomplete or no break down of blood cells?
2. Beta
3. Gamma
4. Ca ta lsa se & Oxida se a . Ca ta la se
i. What chemical is used to test for catalase?
ii. Why does a bacteria need to be able to break down this chemical?
iii. What are the two harmless end-products when this chemical is broken down?
• What does a catalase-positive reaction look like? b. Oxida se
i. What does an oxidase-positive reaction look like?
ii. What happens to the test reagent? Does it gain or lose electrons?
5. Ca rbohydra te Ca ta bolism (UN IT 7) a . TSI
i. What are the three nutrients (sugars) in a TSI slant?
ii. What ingredient is an indicator that hydrogen sulfide has been produced?
iii. When a sugar in the TSI test is metabolized, will there be an alkaline or acidic product? What color will the media be?
iv. What colors will you see in slant/butt with the following results? Which sugar, if any, has been digested?
1. K/K
2. K/A
3. A/A
v. What do the following results look like?
1. Gas production
2. H2S production
b. M R/ VP
ii. There are 2 possible pathways for digestion of this nutrient. What are the 2 different products?
1. ____________ 2. ____________
iii. What does a positive MR reaction look like? Which product is being detected?
iv. What does a positive VP reaction look like? Which product is being detected?
c. Citra te
i. What is the nutrient in the citrate test?
ii. If this nutrient is metabolized, what color will the media be? (Positive Reaction)
iii. What color(s) will the media are if the nutrient is not metabolized? (Negative Reaction)
d. Ca rbohydra te Fermenta tion Test
i. What color will the media be if the carbohydrate has been metabolized? (Positive Reaction)
ii. What color will the media be if the carbohydrate has not been metabolized? (Negative Reaction)
iii. What is the purpose of the Durham tube?
6. Protein Ca ta bolism (UN IT 8)
a . Ornithine/ Lysine Deca rboxyla tion
i. What does the decarboxylase enzyme do?
ii. What color will the media be if the bacteria is positive for decarboxylase?
iii. What color will the media be if the bacteria is negative for decarboxylase?
b. Phenyla la nine Dea mina se
i. What does the deaminase enzyme do?
iii. What color will the media be if the bacteria is negative for deaminase?
c. SIM
i. What does the SIM test stand for?
ii. What amino acid is broken down to produce indole?
iii. What chemical is used to detect indole? What color does it turn in the presence of indole?
iv. What is the result when a bacteria is positive for motility?
d. Urea se
i. What does the urease enzyme do?
ii. What does a positive urease test look like?
7. Gra m Positive Orga nisms (UN IT 9) a . Coa gula se
i. What does the coagulase enzyme do?
ii. What does a positive coagulase result look like?
b. DN a se
i. What does the DNase enzyme do?
ii. What does a positive DNase reaction do to the plate?
iii. What causes this change to the media?
c. N ovobiocin Antibiotic Test
i. What is the zone where the bacteria cannot grow called?
ii. What does it mean if the bacteria is “sensitive” to the antibiotic? If it is “resistant?
8. Gra m Positive Orga nisms II (UN IT 10) a. TSA w/ Blood (see CNA)
i. What results do the following types of hemolysis produce? Is it complete, incomplete or no break down of blood cells?
1. Alpha
3. Gamma
ii. Bactracin is used to distinguish between bacteria that produce what kind of hemolysis?
iii. Optochin is used to distinguish between bacteria that produce what kind of hemolysis?
b. Bile E sculin
i. If a bacteria is positive for Bile Esculin digestion, what color will the media turn?
ii. Does a positive on the Bile Esculin test mean that a bacteria is a true beta or a true gamma hemolyser?
c. CAM P
i. Why is it sometimes necessary to do the CAMP test? (Which 2 types of hemolysis are sometimes confused?)
ii. Does a positive on the CAMP test mean that a bacteria is a true beta or a true gamma hemolyser?
