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Microbiology Lab > Exam 3 > Flashcards

Exam 3 Flashcards

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1
Q

dormant cells when conditions (temp and nutrient depletion) are unsuitable

A

endospores

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2
Q

what are endospores highly resistant to

A

heat and chemicals

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3
Q

what is endospore resistance due to

A

keratin (outer covering resists staining), dehydrated state, DNA protective proteins

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4
Q

what do endospores have total absence of

A

ATP

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5
Q

these are metabolically active

endospores turn into this when conditions are suitable

A

vegetative cells

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6
Q

method of staining endospores

A

Schaeffer-Fulton

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7
Q

what is the primary stain of Schaeffer Fulton procedure

A

malachite green(forced into spore by steaming)

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8
Q

this is water soluble and has a low affinity for cellular material

A

malachite green

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9
Q

these are responsible for producing the endospore

A

spore mother cells

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10
Q

what are the three possible locations of endospores

A

central, terminal and subterminal

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11
Q

what are the two possible shapes of endospores

A

spherical and elliptical

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12
Q

what is the endospore stain used for

A

to detect presence, shape and location of endospores in bacterial cells

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13
Q

what are two common genra that carry endospores

A

Bacillus and Clostridum

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14
Q

what are the general steps of endospore staining

A

1)heat fix 2)steam with malachite green 3)rinse with DI water 3) counterstain with safrainin

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15
Q

what is the oxidase test designed to identify

A

the presence of cytochrome c oxidase

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16
Q

what converts enzymes back to their oxidized state

A

electron transport chain

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17
Q

what are the two mechanisms of ETC

A

1) transport electrons down chain to terminal electron acceptor
2) generate proton motive force by pumping H

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18
Q

what are unable to donate protons in ETC

A

flavoproteins, iron sulfur proteins, and cytochromes

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19
Q

tetramethyl p phenylenediamine

chemicals that develop color as oxidize

A

cheromogenic reducing agent

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20
Q

what does a dark blue/purple result after 20 sec of oxidase test mean

A

positive result, cytochrome c oxidase is present

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21
Q

what does no color change after 20 sec of oxidase test mean

A

negative result, cytochrome c oxidase is not present

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22
Q

these are natural antimicrobial agents produced by microbes

A

antibiotics

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23
Q

tool for establishing the effectiveness of antimicrobics against pathogenic microbes in clinical labs

A

Kirby-Bauer

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24
Q

what occurs as the drug moves through the agar in Kirby Bauer

A

concentration gradient is formed

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25
forms if organism is susceptible to drug | area around disk where concentration is high enough to strop growth
zone of inhibition
26
junction where concentration of antimicrobic has become too low to stop growth
minimum inhibitory concentration (MIC)
27
does a clear zone mean the bacteria has been killed
no
28
drugs that kill the organism
bactericidal
29
drugs that stop bacteria from dividing (does NOT kill)
baceriostatic
30
zone diameter below which all resistant strains fall
resistance breakpoint
31
zone of diameter above which all susceptible strains fall
susceptibility breakpoint
32
what is the disk diffusion test a method to measure
the effectiveness of antibiotics and other chemotherapeutic agents on pathogenic microbes
33
what is MacConkey agar selective for
gram negative organisms
34
what do the indicators of MacConkey do
differentiate lactose fermenters from lactose non fermenters
35
what does MacConkey agar contain
bile salts, lactose, neutral red, and crystal violet
36
what do the bile salts and crystal violet of MacConkey do
inhibit growth of gram positive organisms
37
when is neutral red dye, red and colorless
colorless above pH 6.8 and red below
38
what is MacConkey agar used for
to differentiate members of Enterobacteriaceae based on the ability to ferment lactose
39
what does poor or no growth on MacConkey agar mean
inhibited by CV and or bile salts so gram positive
40
what does good growth on MacConkey agar mean
not inhibited by CV and or bile salts so gram negative
41
what does pink/red growth on MacConkey agar mean
produces acid from lactose fermentation so coliform
42
what does colorless growth on MacConkey agar mean
does NOT ferment lactose so noncoliform
43
what is the oxidation fermentation test designed for
to differentiate bacteria on the basis of fermentation or oxidative metabolism of carbohydrates
44
oxidative organisms oxidize
carbohydrate to CO2, H2O and energy
45
what is the process of oxidation and fermentation
glycolysis-oxidation of pyruvate-citric acid cycle-ETC
46
what is the significance of high sugar to peptone ratio in oxidation fermentation test
to reduce possibility that alkaline products from peptone utilization will neutralize weak acids
47
what are the pH results of bromothymol blue dye
yellow(6), green (7.1), blue (7.6)
48
what is the oxidation fermentation test medium composed of
glucose, lactose, sucrose, maltose, mannitol, or xylose
49
what is the significance of sealing a tube with sterile mineral oil
promote anaerobic growth and fermentation | creates environment unsuitable for oxidation
50
why is a tube left unsealed
to allow for aerobic growth and oxidation
51
sealed green or blue and unsealed yellow mean
oxidation
52
sealed yellow and unsealed yellow
oxidation and fermentation or just fermentation
53
slightly yellow at top both sealed and unsealed
oxidation and slow fermentation or just slow fermentation
54
green or blue both sealed and unsealed
no sugar metbaolism
55
semisolid medium designed to detect bacterial motility
motility test agar
56
what is the concentration of motility test agar
0.4% to maintain form but allow movement of motile bacteria
57
this is added to make interpretation of motility test easier
tetrazolium salt (TTC)
58
what is used as an electron acceptor
TTC
59
in its oxidized form TTC is
colorless and soluble
60
in its reduced form TTC is
red and insoluble
61
what does a positive motility test look like
red radiating outward from central stab
62
what is an important differential characteristic of Enterobacteriaceae
motility

Microbiology Lab (25 decks)

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