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MICRB 107 - Exam 2 > Microbial Metabolism > Flashcards

Microbial Metabolism Flashcards

1
Q

Define metabolism

A

All chemical reactions in an organism

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2
Q

Define catabolism

A

Breakdown of larger molecules into smaller ones

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3
Q

Define anabolism

A

Synthesis of larger molecules from smaller molecules

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4
Q

What are the results of oxidation in cellular respiration? (2)

A
  • CO₂
  • Water
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5
Q

What is the result of oxidation in fermentation?

A

Organic waste products

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6
Q

Which is more efficient at extracting energy from organic molecules – cellular respiration or fermentation?

A

Cellular respiration

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7
Q

When does fermentation occur?

A

When cells lack a terminal electron acceptor and cannot carry out cellular respiration

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8
Q

The synthesis of ATP without the electron transport chain is known as ______

A

Substrate-level phosphorylation

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9
Q

The synthesis of ATP using a proton motive force generated via electron transport chain is known as ______

A

Oxidative phosphorylation

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10
Q

34 molecules of ATP are oxidatively phosphorylated via ______

A

Chemiosmosis

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11
Q

How is the bulk of ATP (34 out of 38 per molecule of glucose) generated via respiration? (3)

A
  • Glycolysis - 2 NADH (6 ATP)
  • Synthesis of acetyl-coA - 2 NADH (6 ATP)
  • Krebs cycle - 6 NADH (18 ATP) and 2 FADH₂ (4 ATP)
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12
Q

What is the essential function of fermentation in terms of making glycolysis possible?

A

Regeneration of NAD+

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13
Q

NADH reduces pyruvic acid in which type of fermentation?

A

Lactic acid fermentation

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14
Q

Pyruvic acid undergoes decarboxylation to form ethanol in which type of fermentation?

A

Alcoholic fermentation

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15
Q

What is decarboxylation?

A

CO₂ is given off

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16
Q

What microbe is responsible for alcoholic fermentation?

A

Saccharomyces cerevisiae

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17
Q

Describe how alcoholic fermentation serves as a means of preservation

A

End products prevent growth of spoilage microbes

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18
Q

What 3 ingredients or conditions are necessary to make wine?

A
  • Sugar
  • Yeast
  • Anaerobic conditions
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19
Q

Describe how lactic acid fermentation serves as a means of preservation

A

Regulates pH and prevents growth of microbes

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20
Q

What microbes are responsible for lactic acid fermentation? (2)

A
  • Streptococcus
  • Lactobacillus
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21
Q

In practice, what is the difference between the “O” and “F” tubes?

A
  • O tube = aerobic
  • F tube = anaerobic oil overlay
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22
Q

Indicate the carbohydrate used in the oxidative / fermentative catabolism test

A

Glucose

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23
Q

What is the pH indicator in the oxidative / fermentative catabolism test?

A

Bromothymol blue

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24
Q

Describe the expected color changes at a basic pH in the oxidative / fermentative catabolism test

A

Green

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25
Q

Describe the expected color changes at an acidic pH in the oxidative / fermentative catabolism test

A

Yellow

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26
Q

______ acidify the O/F glucose medium

A

Fermenters

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27
Q

Indicate the 3 different carbohydrates used in the Durhman sugar tube test

A
  • Glucose
  • Lactose
  • Sucrose
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28
Q

What is the pH indicator in the Durham sugar tube test?

A

Phenol red

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29
Q

Describe the expected color changes at a basic pH in the Durham sugar tube test

A

Red

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30
Q

Describe the expected color changes at an acidic pH in the Durham sugar tube test

A

Yellow

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31
Q

What are the expected results of gas production for the Durham sugar tube test?

A

Bubbles

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32
Q

Indicate the carbohydrate used in the methyl red (MR) test

A

Glucose

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33
Q

What type of fermentation is detected by the methyl red (MR) test?

A

Mixed-acid fermentation

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34
Q

What is the pH indicator in the methyl red (MR) test?

A

Methyl red

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35
Q

What color would be associated with a positive methyl red (MR) test?

A

Red

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36
Q

What color would be associated with a negative methyl red (MR) test?

A

Yellow

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37
Q

What type of fermentation is detected by the Voges-Proskauer (VP) test?

A

Butanediol fermentation

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38
Q

Place the following in the correct order according to the 2,3-butanediol fermentation pathway: 2,3-butanediol, acetoin, glucose

A
  • Glucose
  • Acetoin
  • 2,3-butanediol
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39
Q

Place the following in the correct order according to the color development: diacetyl, acetion, red color

A
  • Acetoin
  • Diacetyl
  • Red color
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40
Q

Hydrogen peroxide (H₂O₂) is a ______ in aerobic respiration

A

Highly reactive oxidizing agent

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41
Q

How does the enzyme catalase ‘detoxify’ H₂O₂ (what is the actual chemical reaction)?

A

H₂O₂ → H₂O + O₂

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42
Q

What causes the formation of bubbles due to catalase activity in the catalase test?

A

Hydrogen peroxide

43
Q

Cytochrome c oxidase is an enzyme in the ______

A

Electron transport chain

44
Q

What specific role does cytochrome c oxidase play in aerobic respiration?

A

Transfers electrons to O₂

45
Q

What role does molecular oxygen (O₂) play in aerobic respiration?

A

Terminal electron acceptor

46
Q

What is the role of tetramethyl-p-phenyl-edediamine?

A

Artificial electron donor

47
Q

When electrons are transferred from reduced tetramethyl-p-phenyl-edediamine to cytochrome C, the sample turns ______

A

Blue

48
Q

How are anaerobic respiration and the reduction of nitrate (NO3-) to nitrite (NO2-) (or other reduced forms of nitrate) related?

A

Some bacteria use nitrate as a terminal electron acceptor during anaerobic respiration

49
Q

What is the role of “nitrate reductase” in anaerobic respiration?

A

Transfer of electrons from cytochrome B to nitrate

50
Q

During the reduction of nitrate to nitrite, cultures are grown in ______ with Durham tubes

A

Nitrate broths

51
Q

What color would be associated with a positive reduction of nitrate to nitrite?

A

Red

52
Q

Why is Simmon’s Citrate Medium a defined medium?

A

The amount and source of all ingredients are known

53
Q

______ is the sole carbon source in Simmon’s Citrate Medium

A

Sodium citrate

54
Q

______ is the sole nitrogen source in Simmon’s Citrate Medium

A

Ammonium

55
Q

How do ‘citrate-positive’ organisms obtain their citrate from the environment – what is the name of the transporter?

A

Citrate-permease transports citrate into the cell

56
Q

What occurs if a bacterium lacks citrate-permease?

A

The bacteria will NOT survive on the medium

57
Q

What is the pH indicator in Simmon’s Citrate Medium?

A

Bromothymol blue

58
Q

Ammonia and ammonium hydroxide are produced by citrate-positive bacteria because they …

A

They alkalize the medium (turn it blue)

59
Q

What color would be associated with a positive Citrate Test?

A

Blue

60
Q

What color would be associated with a negative Citrate Test?

A

Green

61
Q

Enzymes that catalyze the removal of an amino acid’s carboxyl group are known as ______

A

Decarboxylases

62
Q

Enzymes that catalyze the removal of an amino acid’s amine group (NH₂) are known as ______

A

Deaminases

63
Q

Name the carbon source and specific amino acid in the Moller’s Decarboxylation Medium used in the lab

A

Lysine

64
Q

What is the pH indicator in Moller’s lysine decarboxylase medium?

A

Bromocresol purple

65
Q

What color would be associated with a positive Moller’s lysine decarboxylase medium?

A

Purple

66
Q

What color would be associated with a negative Moller’s lysine decarboxylase medium?

A

Yellow

67
Q

A mineral overlay used in the decarboxylation / deamination test to promote ______

A

Fermentation

68
Q

In Moller’s lysine decarboxylase medium, glucose initially turns the medium ______ due to the end products of fermentation

A

Yellow

69
Q

In Moller’s lysine decarboxylase medium, decarboxylation of lysine results in the accumulation of alkaline end products that turn the medium ______

A

Purple

70
Q

Low pH and the presence of the specific amino acid induces ______ to produce the enzyme

A

Decarboxylase-positive organisms

71
Q

What occurs if the organism is capable of fermenting glucose and decarboxylating lysine?

A

Accumulation of alkaline end products

72
Q

What substrate is required for phenylalanine deaminase?

A

Oxygen

73
Q

What are the products for phenylalanine deaminase? (2)

A
  • Ammonia (NH₃)
  • Phenylalanine acid
74
Q

______ provides a rich source of phenylalanine

A

Phenylalanine agar

75
Q

Of the 2 products of phenylalanine deaminase activity, which one reacts with ferric chloride (FeCl3)?

A

Phenylpyruvic acid

76
Q

What happens to the sample when phenylpyruvic acid reacts with the ferric chloride?

A

Turns a dark green color almost immediately

77
Q

Describe hydrolysis reactions

A

Uses water to split complex molecules

78
Q

______ are required for hydrolytic reactions

A

Hydrolytic enzymes

79
Q

What is esculin?

A

A vasoprotective agent that provides nutrients

80
Q

Esculin is composed of ______

A

Glycoside

81
Q

What is glycoside?

A

Sugar composed of glucose and esculetin

82
Q

What are the hydrolysis products of esculin catabolism? (2)

A
  • Esculin
  • Glucose
83
Q

What role does esculin play in the differential quality of the Bile Esculin Test?

A

Catabolizes into glucose

84
Q

What role does bile play in the selective quality of the Bile Esculin Test?

A

Selective for group D streptococci and enterococci

85
Q

When esculin molecules are split, esculentin reacts with ______ in the medium

A

Ferric citrate

86
Q

A ______ is formed when esculentin reacts with ferric citrate

A

Phenolic iron complex

87
Q

What color would be associated with a positive Bile Esculin Test?

A

Dark brown

88
Q

Starch is a polysaccharide composed of ______

A

ɑ-D-glucose subunits

89
Q

Differentiate between amylose and amylopectin

A
  • Amylose - linear
  • Amylopectin - branched
90
Q

What kind of linkage holds linear molecules of glucose together in amylose?

A

1,4-ɑ-glycosidic linkages

91
Q

What kind of linkage attaches side chains of amylopectin to the main chain?

A

1,6-ɑ-glycosidic linkages

92
Q

What specific reactions do “a-amylase” and “oligo-1,6-glucosidase” enzymes catalyze?

A

Starch into glucose by breaking glycosidic linkages

93
Q

Explain the principle of using starch agar to detect starch hydrolysis

A

Organisms hydrolyze the starch in the area surrounding their growth

94
Q

What role does iodine play in detecting starch hydrolysis?

A

Reacts with starch

95
Q

What kind of color reaction develops between iodine and starch?

A

Blue / dark brown

96
Q

What color would be associated with a positive starch hydrolysis test?

A

Clear

97
Q

What are the hydrolysis products of urea? (2)

A
  • Ammonia (NH₃)
  • Carbon dioxide (CO₂)
98
Q

______ catalyzes the hydrolysis of urea into carbon dioxide and ammonia

A

Urease

99
Q

What is the main nutritional source in Urea Broth?

A

Yeast extract

100
Q

What is the pH indicator in the Urease Test?

A

Phenol red

101
Q

What color would be associated with alkaline results of urea hydrolysis?

A

Pink

102
Q

What color would be associated with neutral results of urea hydrolysis?

A

Red / orange

103
Q

What color would be associated with acidic results of urea hydrolysis?

A

Yellow

104
Q

What color would be associated with a positive urease organism?

A

Pink

MICRB 107 - Exam 2 (3 decks)

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