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Microbiology 211 Lab > Quiz 2 Updated > Flashcards

Quiz 2 Updated Flashcards

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Biology 101 flashcards
1
Q

Why do we use the gram stain?

A

To help us differentiate between gram - and gram + cells.

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2
Q

What are the four reagents used in gram stain?

A

Crystal violet (primary dye)
Iodine (mordant)
Ethanol (decolorizer)
Safranin (counter stain)

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3
Q

What is the chemistry of crystal violet in gram stain?

A

The crystal violet binds to all bacteria because it is a cationic dye, attracting to the anionic exterior of the cell

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4
Q

What is the chemistry of iodine in gram stain?

A

The iodine helps the crystal violet “stick better” to the bacteria by forming a complex

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5
Q

What is the chemistry of ethanol in gram stain?

A

The ethanol dissolves lipids and since the gram - bacteria have an outer cell membrane, it will get dissolved and flush out the crystal violet

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6
Q

What is the chemistry of safranin in gram stain?

A

The safranin helps the gram - cells stain pink. Since the ethanol dissolved their color and outer membrane, we need to counterstain so that we can see gram - cells.

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7
Q

What is the structure of gram + bacteria?

A

We have an inner cell membrane and a thick peptidoglycan layer

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8
Q

What is the structure of gram - bacteria?

A

We have an inner cell membrane, a thin peptidoglycan layer, and an outer cell membrane

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9
Q

What is the color of gram - and gram+ after staining?

A

Gram - : pink/red

Gram + : purple

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10
Q

What would happen if safranin was left out?

A

We would not see the gram - cells

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11
Q

What would happen if ethanol was left out?

A

We would not be able to differentiate gram - from gram + because the gram - would retain the purple

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12
Q

What would happen if iodine was left out?

A

It would be harder to differentiate because the crystal violet would wash out from both gram - and gram +

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13
Q

What would happen if the cultures we used in gram stain were old?

A

It could alter our results because the cell walls would become thin so crystal violet and iodine would not work effectively

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14
Q

What is the acid fast stain? What is its purpose?

A

The acid fast stain is another differential stain that is used to identify the mycobacterium species based on it’s mycolic acid layer

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15
Q

What is the main pathogen and disease associated with mycolic acid?

A

Mycobacterium TB and the disease is Tuberculosis

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16
Q

What reagents are used in acid fast stain?

A

Carbolfushion (primary dye)
Acid- Alcohol (decolorizer)
Methylene blue (counter stain)

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17
Q

Why is mycolic acid a virulence factor?

A

Because it helps bacteria resist chemical damage, dehydration and antibiotics

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18
Q

What is an endospore?

A

A specialized structure that some bacteria form when their environment is threatened

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19
Q

Endospores only occur in which 2 genera?

A

Clostridium and Bacillus

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20
Q

What reagents do we use for endospore stain? What is the name of this method?

A

Malachite Green (primary dye)
Safranin (counterstain)
This is the Schaeffer-Fulton method.

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21
Q

What is a vegetative state?

A

When a bacteria is active (without a spore)

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22
Q

What is a capsule?

A

Can be referred to as glycocalyx and they protect the cell from outside environment

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23
Q

Why are capsules a virulence factor?

A

They protect bacteria and let them flourish despite the harsh conditions

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24
Q

Why is a capsule stain also called negative stain?

A

Because in this procedure, we are not actually staining the capsule, we are staining the background and the bacteria.

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25
Q

What is a biofilm?

A

When microorganisms or a microbial community grows and reproduces on a surface.

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26
Q

What reagents do we use in capsule staining?

A

Congo Red and Maneval’s stain

27
Q

What is the ultimate goal of T-streak?

A

To have isolated colonies

28
Q

What is microbial flora?

A

A population of microprganisms that grow on a surface

29
Q

What is quality control

A

A method that we use to make sure our results are accurate.

30
Q

What is a biofilm?

A

A microbe community that grows on a surface

31
Q

What is the goal of T streak?

A

To have isolated colonies

32
Q

What is quality control?

A

A method that we use to ensure our techniques are accurate

33
Q

What is transient microbes?

A

Temporary skin contaminants that may be pathogenic

34
Q

What is resident microbes?

A

Permanent normal skin contaminants that are not generally pathogenic

35
Q

What can we use bacterial plate counts for?

A

We can use bacterial plate counts for water, milk and food quality

36
Q

Why do we use serial dilutions?

A

Because our original sample is too concentrated so weuse this method to count them

37
Q

What is a diluent?

A

A fluid that we use to dilute a sample

38
Q

What is an aliquot?

A

The smaller volume we get from the sample

39
Q

What is the dilution factor?

A

The total volume of diluted solution / aliquot volume

40
Q

What is the oxic zone?

A

The zone where there is some oxygen

41
Q

What is the anoxic zone?

A

The zone with little to no oxygen

42
Q

What are some examples of facultative anaerobes?

A

Bacillus Subtilis, Staphylococcus, corynebacterium

43
Q

What is an example of aerotolerant anaerobe?

A

Clostridium sporonges.

44
Q

What is the optimum growth temperature?

A

The temperature at which the species will grow the fastes

45
Q

What is diffusible pigments?

A

Pigments that can change agars color (soluble)

46
Q

What is non-diffusible pigments?

A

Pigments that are only present in the colony

47
Q

What are pigments controlled by?

A

Enzyme activity

48
Q

What ishypertonic?

A

When the concentration on the outside is higher than the inside of the cell

49
Q

What is hypotonic?

A

When the concentration outside the cell is lower than the inside of the cell

50
Q

What is plasmolysis?

A

When a hypertonic cell shrivels up

51
Q

What is cell lysis?

A

When a hypotonic cell swells up

52
Q

What is halophile?

A

Salt loving organisms

53
Q

What is neutral pH?

A

6.5-7.5

54
Q

What is an Acidophile?

A

bacteria that prefer acidic conditions (under 6.5)

55
Q

What is alkaline bacteria?

A

Bacteria that prefer alkaline conditions (above 7.5)

56
Q

1 mL = ? microliters?

A

1000 microliters

57
Q

What is the range of a valid count

A

30-300

58
Q

What is a strict aerobe?

A

Cannot exist without oxygen

59
Q

What is a strict anaerobe?

A

Cannot exist with oxygen

60
Q

What is a facultative anaerobe?

A

A bacteria that can grow with or without oxygen

61
Q

What is an aerotolerant anaerobe?

A

Bacteria that uses oxygen for growth but doesnt need it to live

62
Q

What is a microaerophile?

A

Bacteria that grows best with oxygen is low and co2 is high

63
Q

What is an example of strict anaerobe?

A

clostridium perfringens

Microbiology 211 Lab (5 decks)

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