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Biology 15 - General Microbiology > Lab Exam 3 Gram - > Flashcards

Lab Exam 3 Gram - Flashcards

(58 cards)

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1
Q

You should know a few of the potential genera used in the unknown experiment.

A
  1. Escherichia
  2. Pseudomonas
  3. Citrobacter
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2
Q

For each test, you should know what a positive test result looks like and what a negative test result looks like.

A
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3
Q

What color is the Simmons’ slant before it is inoculated?

A

Green

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4
Q

The Simmons’ slant contains bromothymol blue. In this case, the pH indicator will not turn yellow. What color is a Simmons’ slant that is positive for nutrient utilization?

A

Blue

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5
Q

What color is the tube before it is incubated? Simmons slant test.

A

Green

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6
Q

What is the carbon source in the Simmons’ slant?

A

Citrate

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7
Q

What is the nitrogen source in the Simmons’ slant?

A

Ammonia

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8
Q

How does nutrient utilization affect the pH of the Simmons’ slant?

A

Increases pH, making it more alkaline

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9
Q

Litmus Milk

Litmus milk broth contains two key ingredients, skim milk and litmus powder. What are the two functions of the litmus powder in the litmus milk broth?

A

1.) pH indicator
2.) Litmus can be reduced

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10
Q

Litmus Milk

What are the three reactions that can occur with the litmus powder?

A

1.) Purple = negative for fermentation (alkaline)
2.) Pink = positive for fermentation (acidic)
3.) White = reduction (can see white at bottom of tube)

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11
Q

Litmus Milk

Each of the litmus reactions produce a different color. Match each of the three litmus reactions to pink, purple, or white.

A

1.) Purple = negative for fermentation (alkaline)
2.) Pink = positive for fermentation (acidic)
3.) White = reduction (can see white at bottom of tube)

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12
Q

Litmus Milk

What are the two possible reactions that can occur with the milk protein in the litmus milk broth?

A

1.) pH indicator
2.) Litmus can be reduced

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13
Q

Litmus Milk

What is peptonization?

A

Enzymes breakdown proteins into peptides

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14
Q

Litmus Milk

How will coagulation affect the broth?

A

Broth solidifies

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15
Q

Litmus Milk

What causes the broth to coagulate?

A

Too much acid release into media

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16
Q

SIM stab

What does the abbreviation ‘SIM’ stand for?

A
  • Sulfide
  • Indole
  • Motility
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17
Q

SIM stab

Which of the three tests did we not record data for?

A

Motility

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18
Q

SIM stab

Which amino acid is degraded to produce ‘S’?

A

Cysteine

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19
Q

SIM stab

What is the enzyme that is responsible for ‘S’?

A

Cysteine desulfurase.

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20
Q

SIM stab

What are the three products that are produced as part of ‘S’?

A

Hydrogen sulfide (H2S), pyruvic acid, and ammonia

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21
Q

SIM stab

What are the three products that are produced as part of ‘S’?

A

Hydrogen sulfide (H2S), pyruvic acid, and ammonia.

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22
Q

SIM stab

Which specific product of the three is detected by ‘S’?

A

Hydrogen sulfide (H2S)

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23
Q

SIM stab

What color is a positive ‘S’ test?

A

Black precipitate

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24
Q

SIM stab

Which amino acid is degraded to produce ‘I’?

25
# SIM stab What is the enzyme that is responsible for ‘I’?
Tryptophanase
26
# SIM stab What are the three products that are produced as part of ‘I’?
Indole, pyruvic acid, and ammonia
27
# SIM stab Which specific product of the three is detected by ‘I’?
Indole
28
# SIM stab What reagent is used to test for ‘I’?
Kovac's reagent
29
What color is a positive ‘I’ test?
Red ring at the top of tube
30
# MRVP What does the abbreviation ‘MRVP’ stand for?
Methyl Red Voges-Proskauer
31
# MRVP Which reagent tests for the production of mixed acids by fermentation?
Methyl red reagent
32
# MRVP How does the color of the reagent that tests for mixed acid fermentation change with decreasing pH?
Turns red with decreasing pH
33
# MRVP How many days does the 2,3-butanediol test using an MRVP tube incubate for?
5 days
34
# MRVP/2,3-butanediol Why doesn’t 2,3-butanediol react with a pH indicator, like phenol red?
Because alcohol doesn't change the pH, therefore the pH indicator doesn't react.
35
# Vogues Proskaver What is the exact procedure for performing the VP test in lab?
1. Label empty test tube for our unknown 2. Pipette 1 ml of MRVP into the unknown tube 3. Add 18 drops of reagent A and 18 drops of reagent B to the unknown tube 4. Shake tube every 10 minutes 5. After 30 minutes, check color
36
# Vogues Proskaver What is the purpose of shaking the small tube?
We shake to **oxidize** **acetoin into diacetyl** (if its's present)
37
# Vogues Proskaver Which final chemical product will be created in the VP test?
Diacetyl
38
# Vogues Proskaver How long does the VP test sit before the color change is complete?
30 Minutes
39
What color is a positive VP test? What color is a negative test result?
* Positive: Red * Negative: Brown
40
# Brilliant Green Agar What kills Gram + & some Gram – in the Brilliant Green Agar? (how is it selective?)
Brilliant green dye selects against gram + bacteria, and some gram - bacteria.
41
# Brilliant Green Agar What sugars are found in the Brilliant Green? | Hint: Two of them
1. Sucrose 2. Lactose
42
# Brilliant Green Agar What is the pH indicator for the Brilliant green agar?
Phenol red
43
# Brilliant Green Agar What color is brilliant green agar that is positive for fermentation (Acidic)?
Lime green
44
# Brilliant Green Agar What color is brilliant green agar for a nonfermenter (Basic)?
Bright pink
45
# Brilliant Green Agar What color is brilliant green agar when the bacteria is dead (negative)?
Orangish-Brown since the plate remains the same color
46
# Catalase Test What type of media was used for the catalase test?
Hydrogen peroxide (H2O2)
47
# Catalase Test You should be able to write out the complete catalase reaction, including the names and molecular formulas of all substrates and products.
Catalase reaction: 2 H2O2 → 2 H2O + O2 * Substrate: Hydrogen Peroxide * Product: Water and Oxygen
48
Briefly describe the appearance of a positive catalase test.
Bubble formation
49
Which product of catalase activity is responsible for the visible reaction?
Oxygen gas
50
What is the protein cytochrome oxidase normally used for? Where specifically is cytochrome oxidase located?
Cytochrome oxidase is involved in the electron transport chain. It is located in the bacterial cell membrane.
51
What is the exact reaction of cytochrome oxidase?
The reduction of cytochrome c using oxygen as the final electron acceptor
52
What color is a positive cytochrome oxidase test?
Dark purple
53
What type of media was used for the oxidase test?
TSA plate streaked with the unknown on one half and Pseudomonas aeruginosa on the other half.
54
What is in the Hektoen agar that makes it selective?
Bile
55
# Hektoen Agar What three carbohydrates does it contain?
1. Lactose 2. Sucrose 3. Salicin
56
# Hektoen Agar What are the pH indicators?
1. Bromthymol Blue 2. Andrades Acid
57
# Hektoen Agar What is the fermentation color change (acidic)?
Turns Bright Orange
58
# Hektoen Agar What is the non-fermenter color change (basic)?
Blue-Green

Biology 15 - General Microbiology (29 decks)

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