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Microbiology > Lab Quiz 3 > Flashcards

Lab Quiz 3 Flashcards

0
Q

What does EMB medium differentiate?

A

Degree of lactose fermentation

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1
Q

What kind of medium is Eosin Methylene Bromide?

A

Differential, Selective, Undefined

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2
Q

What does EMB medium select for?

A

Encourages Gram - growth

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3
Q

What is a color form bacteria?

A

A rod shaped, gram negative, lactose fermenter

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4
Q

What bacteria showed the highest degree of lactose fermentation?

A

E. coli, showed a green metallic color.

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5
Q

What is a strict anaerobe?

A

Can only survive without oxygen. Will only grow deep in agar.

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6
Q

What is a Facultative Anaerobe?

A

Can survive in both environments, aerobic and anaerobic

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7
Q

What is an Aerotolerant Anaerobe?

A

Thrives in anaerobic but can survive in aerobic

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8
Q

What are microaerophiles?

A

Survive in small oxygen concentrations only

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9
Q

What are strict aerobes?

A

Can only survive in aerobic environments

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10
Q

What does the Fluid Thiogycolate Medium test for?

A

Growth in different oxygen concentrations

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11
Q

What does the anaerobic container system test?

A

Growth in anaerobic conditions

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12
Q

How does the anaerobic container work?

A

Pump H2 gas into the chamber to produce water with oxygen in the tank. The water condenses in plastic around the chamber.

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13
Q

What is an acidophile?

A

Grows in acidic conditions

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14
Q

What is a neutrophils?

A

Grows in neutral environments

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15
Q

What is an alkaliphile?

A

Grows in basic environment

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16
Q

Why do you out a buffer in broth when you are testing for growth in various pH?

A

Helps keep pH constant in the range for optimal bacterial growth

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17
Q

What is hypotonic?

A

Higher ion concentration inside of the cell. Will result in an influx of water into the cell.

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18
Q

What is hypertonic?

A

Lower ion concentration induce the cell. Result in rush of water out of the cell

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19
Q

What does the Phenol Red Broth test for?

A

Fermentation or Deamination

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21
Q

What does it mean if a Phenol Red Broth turns yellow?

A

Bacteria is positive for fermentation. Fermentation causes release of organic acids which lower the pH of the broth. Phenol Red is Yellow in acidic environments

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22
Q

What does it mean if a Phenol Red Broth stays red?

A

Bacteria is negative for fermentation. Phenol Red is Red in neutral pH. No acid was released in the medium

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23
Q

What does it mean if a Phenol Red Broth turns pink?

A

Bacteria is positive for deamination. When the bacteria breaks down proteins in the broth it releases ammonia, which is basic. Phenol red is Pink in basic environments.

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24
Q

What are the three sugars we tested for fermentation?

A

Glucose, Lactose and Sucrose

25
Q

What are the three potential products of fermentation?

A

organic acids, alcohol, gas production

26
Q

Is fermentation an anaerobic or aerobic process?

A

Anaerobic

27
Q

What did the Catalase reactions test?

A

If bacteria contained catalase to break down hydrogen peroxide

28
Q

How was the presence of catalase tested?

A

Observation of bubbles

29
Q

What was tested during the Nitrate Reduction Test?

A

Presence of nitrate reducing enzymes

30
Q

What did it mean if there was gas in the Nitrate Reduction Test?

A

Nitrogen gas was produced. The bacteria broke down nitrate with nitrate reductase and produced nitrogen gas by denritification.

31
Q

What did it mean if the Nitrogen Reduction Test showed presence of NO2 (nitrite) after the addition of Reagents A and B by turning red?

A

The bacteria has nitrate reductase.

32
Q

What did it mean if the Nitrogen Reduction Test showed presence of NO3 (nitrate) after the addition of zinc by turning red?

A

The bacteria has no nitrate reductase. The nitrate was left in the sample in it’s original form.

33
Q

What did it mean if the Nitrogen Reduction Test result showed a colorless sample?

A

The bacteria had transformed all of the nitrogen into other gaseous products like N2O, NO, or NH3

34
Q

What is the Sulfur-Indole-Motility (SIM) Test used for?

A

To test for three bacterial activities: sulfur reduction, indole production from tryptophan and motility.

35
Q

What to enzymes can reduce sulfur in bacteria?

A

Cystein desulferase which uses sulfur to create pyruvate and hydrogen sulfide and Thiosulfurate reduction which reduces sulfur to hydrogen sulfide.

36
Q

How do you know if the SIM Test shows sulfur reduction?

A

Black precipitate throughout the test tube

37
Q

How is indole produced in bacteria?

A

Bacteria that possess the enzyme tryptophanase can hydrolyze tryptophan in the medium to create indole.

38
Q

How is indole production shown in the SIM Test?

A

When Kovac’s reagent is added the top of the sample turns red.

39
Q

How is motility tested for in the SIM Test?

A

If the bacteria is able to grow throughout the agar and not just in the stab it is motile

40
Q

What do hydrolysis reactions do?

A

Use Hydrolytic enzymes and water molecules to break bonds

41
Q

What are intracellular enzymes?

A

Enzymes that exist in the cell and act on molecules that enter the cell

42
Q

What are extracellular enzymes?

A

Enzymes that diffuse into the medium from the cell. Act on molecules that need to be broken down before they can enter the cell

43
Q

What is an example of an intracellular enzyme?

A

Urease

44
Q

What is an example of an extracellular enzyme?

A

Amylase, Cesease, Lipase

45
Q

What does the Casein Hydrolysis test for?

A

Bacterial possession of casease enzyme that breaks down casein protein in milk

46
Q

How do you know if the Casein Hydrolysis test is positive?

A

Clearing in the medium around bacterial growth.

47
Q

What does the Starch Hydrolysis test for?

A

Presence of amylase

48
Q

What does amylase do?

A

Cleaves 1,4 alpha glycosidic linkages in starch molecules

49
Q

How do you know if Starch Hydrolysis test is positive?

A

Clearing in the medium around bacterial growth. Detected by addition of iodine to medium.

50
Q

What does Urea Hydrolysis test for?

A

Presence of urease

51
Q

What does Urease do?

A

Cleaves urea into ammonia and CO2

52
Q

What is the indicator in the Urea Hydrolysis test?

A

Phenol Red

53
Q

Explain a Pink result of a Urea Hydrolysis test:

A

Rapid urea hydrolysis created a basic environment due to large amounts of ammonia produced. Bacteria has strong urease production. Basic environments are indicated by a pink color.

54
Q

Explain a Red/Pink result of a Urea Hydrolysis test:

A

Slow urea hydrolysis created a slightly basic environment due to small amounts of ammonia produced. Bacteria has a weak urease production.

55
Q

Explain a Yellow/Orange result of a Urea Hydrolysis test:

A

No urea hydrolysis. The Phenol Red indicator is detecting an acidic environment as the bacteria produce an acidic environment through their general growth and existence. No urease production.

56
Q

What does the Lipid Hydrolysis test?

A

Bacterial possession of lipase

57
Q

What does lipase do?

A

Breaks down triglycerides into glycerol and 3 fatty acids

58
Q

How do you know if the Lipid Hydrolysis test is positive?

A

Clearing around bacterial growth.

Microbiology (19 decks)

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