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Microbiology > Lab 17 - Biotyping: O2 tolerance > Flashcards

Lab 17 - Biotyping: O2 tolerance Flashcards

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Biology 101 flashcards
1
Q

what does “redox” stand for?

A

reduction-oxidation

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2
Q

in the electron transport chain, NADH and FADH dump electrons on oxygen to form water. What type of reaction is this?

A

Oxygen is REDUCED to water

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3
Q

define oxidation

A

loss of electrons

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4
Q

define reduction

A

gain of electrons

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5
Q

what is the pneumonic for redox reactions?

A

OIL RIG

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6
Q

what does ROS stand for? what does it mean?

A

Reactive oxygen species.
In cells, oxygen can also be reduced to other products called reactive oxygen species (ROS). These are toxic.

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7
Q

why are ROS toxic?

A

because they oxidize (strip electrons from) and inactivate biomolecules. this may lead to cell death

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8
Q

why are detoxification enzymes produced by the cells?

A

to get rid of ROS

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9
Q

what are the two detoxification enzymes?

A

superoxide dismutase and catalase

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10
Q

what does superoxide dismutase do?

A

detoxifies superoxide radical

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11
Q

what does catalase do?

A

detoxifies hydrogen peroxide

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12
Q

What chemical formula is superoxide dismutase a part of?

A

2H+ + 2O2 —–superoxide dismutase——> H202 +O2

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13
Q

What chemical formula is catalase a part of?

A

2H2O2 —-catalase—-> 2H20 + O2

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14
Q

what is the catalase test?

A

used to identify organisms that produce the enzyme catalase

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15
Q

what is a positive catalase test?

A

bubbles formed, indicating the production of oxygen

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16
Q

what is the thioglycolate broth used to do?

A

to determine the oxygen requirements of microorganisms.

17
Q

what are the nutrients in a thioglycolate broth?

A

yeast extract and a casein protein to digest

18
Q

what are the reducing agents in a thioglycolate broth? what does this mean?

A

They are sodium thioglycolate and cystine.
They reduce O2 to H2O

19
Q

what percentage of agar is in a thioglycolate broth? what does this do?

A

A low percentage, 0.75%.
This minimizes O2 diffusion into the tube

20
Q

what is the O2 indicator on the thioglycolate broth? what color is it when oxidized? reduced?

A

resazurin, which is pink when oxidized and clear when reduced

21
Q

where does O2 diffusion happen in a thioglycolate broth?

A

only at the top of the tube

22
Q

in a thioglycolate tube, if there is growth only at the top of the tube, what type of organism is it?

A

Obligate aerobe

23
Q

in a thioglycolate tube, if there is growth only at the bottom of the tube, what type of organism is it?

A

Obligate anaerobe

24
Q

in a thioglycolate tube, if there is more growth at the top of the tube, and less as it goes down, what type of organism is it?

A

Facultative anaerobe

25
Q

in a thioglycolate tube, if there is growth evenly all over the tube, what type of organism is it?

A

aerotolerant anaerobe

26
Q

in a thioglycolate tube, if there is growth a little below the top of the tube, what type of organism is it?

A

microaerophiles

27
Q

what is an anaerobic jar?

A

It is a gas generator envelope, chemicals in the sachet react with O2 to produce CO2 and H2O.
It prevents oxygen from coming in.

28
Q

what does the indicator strip do?

A

It is methylene blue and becomes blue when oxidized and clear when reduced

29
Q

P. aeruginosa:
-Thioglycolate tube:
-Plate WITH O2:
-Plate WITHOUT O2:
-Catalase:

A

-Thioglycolate tube: obligate aerobe
-Plate WITH O2: growth
-Plate WITHOUT O2: no growth
-Catalase: positive

30
Q

E. coli:
-Thioglycolate tube:
-Plate WITH O2:
-Plate WITHOUT O2:
-Catalase:

A

-Thioglycolate tube: facultative anaerobe
-Plate WITH O2: growth
-Plate WITHOUT O2: growth
-Catalase: positive

31
Q

E. faecalis:
-Thioglycolate tube:
-Plate WITH O2:
-Plate WITHOUT O2:
-Catalase:

A

-Thioglycolate tube: aerotolerant anaerobe
-Plate WITH O2: growth
-Plate WITHOUT O2: growth
-Catalase: negative

32
Q

C. sporogenes:
-Thioglycolate tube:
-Plate WITH O2:
-Plate WITHOUT O2:
-Catalase:

A

-Thioglycolate tube: obligate anaerobe
-Plate WITH O2: no growth
-Plate WITHOUT O2: growth
-Catalase: negative

33
Q

usually, will a facultative anaerobe have a positive or negative catalase result?

A

positive

34
Q

usually, will an aerotolerant anaerobe have a positive or negative catalase result?

A

negative

Microbiology (53 decks)

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