lab Flashcards

1
Q

negative stain appearance

A

colorless on dark background

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2
Q

negative dyes

A

india ink, congo red, nigrosin

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3
Q

part of cell most involved in gram staining

A

peptidoglycan layer

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4
Q

The Gram stain is a type of _________ stain because _______is/are used in the procedure.

A

differential, multiple dyes

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5
Q

You are preparing a sample to be gram-stained. You have a tube of mixed bacteria, a loop, slides, staining rack, dyes, and a bacticinerator. What’s your next step?

A

heat fix sample to slide

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6
Q

how can a sample become contaminated?

A

lack of aseptic technique, leaving tube open for too long, not properly heating inoculation tools

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7
Q

sign of bacterial growth in liquid media

A

turbidity (cloudiness)

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8
Q

colony characteristics

A
  • derived from one cell
  • visible to naked eye
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9
Q

fermentation possible end products

A

gas, alcohol, acid

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10
Q

fermentation type of tube

A

phenol red durham tube

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11
Q

fermentation inoculation tool

A

loop for bacteria, needle for yeast

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12
Q

fermentation: yellow color

A

acid production
- lower pH

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13
Q

fermentation: bubbles

A

gas production

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14
Q

fermentation: red color

A

alcohol production

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15
Q

triple sugar iron inoculation tool and technique

A

needle
streak surface, stab butt

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16
Q

tsi slant makeup

A

1% lactose
1% sucrose
0.1% glucose

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17
Q

tsi: yellow butt, red slant

A

glucose only fermented

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18
Q

tsi: whole tube yellow

A

glucose and lactose/sucrose fermented

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19
Q

tsi: black

A

H2S production

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20
Q

tsi: whole tube red

A

no fermentation

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21
Q

tsi: splitting or lifting

A

gas production

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22
Q

starch hydrolysis: media type

A

enriched differential

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23
Q

starch hydrolysis: how to observe

A

after incubation, add 10-15 drops gram’s iodine to plate
whole plate will be dark, zones of lighter color around line indicate a-amylase production

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24
Q

broth to slant tool and technique

A

loop: dip in broth, streak in zig-zag pattern across slant

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25
Q

broth to broth tool and technique

A

loop: dip and dip

26
Q

slant to slant tool and technique

A

needle: take from top, streak slant with needle

27
Q

broth to deep tool and technique

A

needle: dip, stab into deep

28
Q

sign of bacterial growth in deep

A

growth along stab line

29
Q

sign of bacterial growth in slant

A

zig-zag growth pattern

30
Q

spread plate: dilution

A

take loopful of bacteria and place into sterile saline, mix well

31
Q

spread plate: spread technique

A

take 0.1 mL of saline mix and spread onto TSA plate using flamed hockey stick

32
Q

streak plate: 4 types of media used

A

blood agar
mannitol salt agar
MacConkey agar
EMB agar

33
Q

streak plate: mixture and tool used

A

mix of s.aureus, e.coli, p.vulgaris
spread with loop

34
Q

streak plate: mannitol salt agar colony

A

s. aureus: circular, flat, white
selected for on this agar bc it is mannitol +

35
Q

streak plate: blood agar colony

A
  • small white dots, no distinction between species
36
Q

streak plate: EMB agar colony

A

metallic, green growth (e.coli in this mixture)
gram - bacteria

37
Q

streak plate: macconkey agar

A

pink growthg
gram - lactose fermenters

38
Q

kirby-bauer method: negative control

A

water

39
Q

kirby-bauer method: positive control

A

10% bleach

40
Q

kirby-bauer method: resistance measurement

A

zones of inhibition: larger zone = greater resistance

41
Q

IMViC: reaction

A

tryptophan –tryptophanase–> indole + pyruvate ammonia

42
Q

IMViC: dry slide

A
  • tests for indole production
  • positive is red
43
Q

IMViC: methyl red/voges-proskauer media and inoculation

A

MR-VP broth inoculated with looop

44
Q

IMViC: MR-VP transfer

A

take 1/3 of growth culture into empty sterile tube for VP test, leave 2/3 for MR

45
Q

MR test method and results

A

add 4-5 drops of methyl red into tube
red is positive for acid production
mixed acid fermenters

46
Q

IMViC: SIM deep method and results

A

stab with needle
observe for H2S, indole, and motility
H2S = black
indole = red
motility = cloudiness

47
Q

VP test method and results

A

add 12 drops VP reagent A, 4 drops VP reagent B and vortex
red: acetoin positive
yellow: acetoin negative

48
Q

citrate test: method and results

A

streak and stab with needle
green = citrate -
blue = citrate +

49
Q

casein hydrolysis: plate preparation

A

mix agar with skim milk and let solidify

50
Q

casein hydrolysis: inoculation

A

use loop to draw circle in each triad

51
Q

casein hydrolysis: analysis

A

measure zones of proteolysis

52
Q

catalase activity: method

A

use a sterile cotton swab to place bacteria on glass slide
add 1-2 drops H2O2 to slide and watch for bubbles (O2 production)

53
Q

what does VP test for?

A

glucose fermenters: produce 2,3-butanediol and acetoin

54
Q

In the streak plate method, which quadrant should contain the most bacterial growth?

A

quadrant 1

55
Q

fermentation

A
  • biochemical rxn that produces energy under anaerobic conditions
  • organic molecules = electron donors
  • organic intermediates = electron acceptors
56
Q

durham tube

A

traps gas

57
Q

The TSI test must be incubated for a specific time period of

A

18-24 hours

58
Q

casein hydrolysis: positive results

A

bacteria that secrete proteolytic enzymes

59
Q

The enzyme catalase catalyzes the decomposition of __________ to ________ and _______.

A

h2o2; h2o; o2

60
Q

bacteria can convert NO3 into

A

NO2, N2, NH3

61
Q

Nitrate reagents A and B detect the presence of

A

NO2

62
Q

Upon the addition of nitrate reagent C, the control tube should turn

A

red