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Microbiology > Lecture 7: microbial metabolism > Flashcards

Lecture 7: microbial metabolism Flashcards

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1
Q

What type of organisms will use electron sources for their food?

A
  • lithotrophs use reduced inorganic substance

- organotrophs use electrons from organic compounds

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2
Q

Where do phototrophs obtain energy?

A
  • light sources
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3
Q

Where do chemotrophs obtain energy?

A
  • oxidation of chemical compounds
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4
Q

What are the two major types of microorganisms?

A
  • photolithotrophs (photo autotrophs)

- chemoorganoheterotrophs (chemoheterotrophs)

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5
Q

How does microbial metabolism impact our lives as humans?

A
  • metabolic waste is used as our energy
  • their waste contributes to our disease
  • their processes are targets for antibiotics
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6
Q

What are the three basic needs that organisms need?

A
  • ATP for energy
  • ability to reduce compounds to produce electrons
  • metabolites for biosynthesis
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7
Q

What type of processes can chemoorganotrophic organisms use to “refuel”

A
  • anaerobic respiration
  • aerobic respiration
  • fermentation
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8
Q

What are the different exogenous acceptors of the final electron in anaerobic respiration?

A
  • nitrate
  • sulfate
  • carbon dioxide
  • ferric iron
  • selenium tetraoxide
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9
Q

How is ATP generated with fermentation?

A
  • formed by substrate level phosporylation

- electron acceptor is normally endogenous (pyruvate)

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10
Q

What is a catabolic pathway?

A
  • enzyme catalyzed reaction where the product of one reaction serves as the substrate for the next reaction
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11
Q

What are three important amphibolic pathways?

A
  • embden meyerhof pathway
  • pentose phosphate pathway
  • tricarboxylic acid (TCA) cycle
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12
Q

What is used in aerobic respiration in order to catabloize an organic energy source?

A
  • glycolysis
  • TCA
  • electron transport chain
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13
Q

What are three common ways to break glucose down to pyruvate?

A
  • pentose phosphate pathway
  • embden meyerhof pathway
  • entner duodoroff pathway
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14
Q

Where does the embden meyerhof pathway most likely occur?

A
  • cytoplasmic matrix
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15
Q

In what stage of aerobic respiration does the embden meyerhof pathway consist of?

A

stage 2

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16
Q

What are the two phases of the embden meyerhof pathway?

A
  • 6 carbon and 3 carbon phase
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17
Q

The embden meyerhof pathway is also known as?

A

glycolysis

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18
Q

What organism uses the Entner-duodoroff pathway?

A
  • gram negative bacteria
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19
Q

What is the cycle of glucose degradation with the entner-duodoroff pathway?

A
  1. glucose (2) glucose-6-p (3) 6-phosphogluconate (4) 2keto3deoxy6phosphogluconate KDPG (5) pyruvate and G3P
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20
Q

What is the reaction of the pentose phosphate pathway?

A

glucose-6-p + 12 NADP + 7 water

6 CO2 + 12 NADPH + 12 H

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21
Q

What is the major role of the TCA cycle?

A

produce carbon skeletons for use in other biosynthetic pathways (FA synthesis…)

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22
Q

What are the products generated with 1 acetyl CoA molecule?

A
  • 2 CO2
  • 3 NADH
  • 1 FADH2
  • 1 GTP
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23
Q

Where are bacterial and archaeal electron transport chains located, and how do they differ from eukaryotes?

A
  • plasma membrane
  • different e- carrier
  • branched
  • shorter
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24
Q

What does the chemiosmotic hypothesis say with regards to electron transport systems?

A
  • the electron movement causes active transport of H ions, creating a proton gradient that can be used to generate ATP
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25
Q

What is the maximum theoretical yield of ATP production and what is reality?

A

theoretically 38

reality 30

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26
Q

What factors can affect the amount of ATP produced in an organism?

A
  • growth/environment conditions

- nature/health of the ETC

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27
Q

What factors will contribute to a lower than expected ATP production?

A
  • shorter ETC
  • environment
  • use PMF to energize other actions
  • use of metabolites for other processes
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28
Q

Why does anaerobic respiration generally yield less ATP than aerobic?

A

the electronegativity of oxygen is much higher than any of the electron acceptors in anaerobic

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29
Q

How is ATP produced in fermentation?

A

substrate level phosphorylation

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30
Q

What is the endogenous electron acceptor in fermentation?

A

pyruvate

31
Q

Streptococcus, lactobacillus and bacillus use pyruvate to form?

A

lactic acid

32
Q

Saccharomyces use fermentation to convert pyruvate to?

A

ethanol and carbon dioxide

33
Q

Propionibacterium use fermentation to convert pyruvate to_______?

A

propionic acid
acetic acid
carbon dioxide and hydrogen

34
Q

Clostridium convert pyruvic acid to what in fermentation?

A

butyric acid, butanol, acetone, carbon dioxide.

35
Q

Escherichia and salmonella convert pyruvate to what product of fermentation?

A

ethanol, lactic acid, succinic acid, acetic acid, carbon dioxide

36
Q

Enterobacteria are able to convert pyruvate to what, via fermentation?

A

ethanol, lactic acid, formic acid, butanediol, acetoin

37
Q

What are some monosaccharides that can be used for energy in pathways?

A
  • galactose
  • glucose
  • mannose
  • fructose
38
Q

What are some di-/polysaccharides that require some amount of cleavage before they can be used in pathways?

A
  • maltose
  • sucrose
  • lactose
  • cellobiose
39
Q

What is polyhydroxybutyrate?

A

a reserve of energy that is converted to acetyl-CoA which can enter the TCA cycle

40
Q

After a protein is degraded and deaminated what can the remaining amino acids be converted back to?

A
  • pyruvate
  • acetyl CoA
  • other TCA intermediates
41
Q

What will the oxidase test for?

A

Determines the presence of cytochrome oxidase

42
Q

If the test strip turns blue for the oxidase test, what does this mean?

A

cytochrome c oxidase is present in the microbe, and uses oxygen as the final hydrogen acceptor

43
Q

If a oxidase test turns the strip blue does this indicate an anaerobic or aerobic microbe?

A

aerobic as oxygen is acting as the hydrogen acceptor

44
Q

What is the catalase test used for?

A

detecting the presence of catalase, which catalyzes the degradation of H2O2 into whater and oxygen

45
Q

What would a positive catalase test look like?

A

upon reagent addition, the sample would produce bubbles, indicating that catalase is present in the microbe

46
Q

What is phenol red broth?

A

a pH indicator

  • yellow = 6.8 or below
  • pink = 7.4 above
  • red = in between
47
Q

In the phenol red broth test, what does a yellow color indicate?

A

Acid production via fermentation process

48
Q

In phenol red broth test, what does a pink color indicate?

A

production of ammonia, as peptides are being deaminated

49
Q

What is the methyl red and voges-proskauer test used to differentiate between?

A

gram negative rods of enterobacteriacea

50
Q

What bacterial activities does the SIM Medium test for presence of?

A
  • sulfur reduction
  • indole production from tryptophan
  • motility
51
Q

What is sulfur reduction useful for differentiating?

A

differentiates between enteric organisms

52
Q

What are the two methods of sulfur reduction?

A
  • cysteine desulfurase (cysteine to pyruvate)

- thiosulfate reductase (sulfur reduction at end of anaerobic ETC

53
Q

Both enzymes, cysteine desulfurase and thiosulfate reductase, produce what product?

A

hydrogen sulfide (H2S)

54
Q

The SIM Medium starts as a yellow solution. What are the results if sulfur reduction is present?

A
  • if present the solution will turn black as the hydrogen sulfide will react with iron to form ferric sulfide
  • if no sulfur reduction occurs the ferric sulfide will not form and no blackening of the solution occurs
55
Q

The SIM Medium can be used to detect the presence of indole, formed as a by-product of tryptophanase.

A
  • if a red reagent layer appears, this indicates the presence of an indole and therefore the presence of tryptophanase
56
Q

The SIM Medium can also detect motility. What indicate the organisms ability to be motile?

A
  • motility will produce a pattern of fuzzy appearance in a semisolid solution
  • no fuzzy appearance indicates no motility
57
Q

SIM Medium works as a whole to differentiate between what two organisms?

A

salmonella and shigella

58
Q

The decarboxylation test will determine if what enzyme is present?

A

decarboxylase presence or absence

59
Q

A positive decarboxylation test will produce what results?

A

a more alkaline solution (>6.8pH) and will be purple

60
Q

A negative decarboxylation test will produce what results?

A

an acidic solution (

61
Q

What is the result of a decarboxylase reaction?

A

R-H and CO2 thereby reducing the amount of H ions

62
Q

With the citrate test, what ways determine if citrate is used for carbon and energy?

A

blue color or green color with sample growth

63
Q

When is citrate not utilized as a source of energy and carbon in the citrate test?

A

green color and no increase of the sample

64
Q

The urea hydrolysis test is used to detect the presence of urease. What does the presence and absence of this enzyme look like?

A
  • presence is a pink end product

- absence is a yellow product

65
Q

What is the purpose of the gelatin hydrolysis test?

A

The purpose is to see if the microbe can use the protein gelatin as a source of carbon and energy for growth. Use of gelatin is accomplished by the enzyme gelatinase

66
Q

What does a positive gelatin hydrolysis test look like and what does it mean?

A
  • gelatin becomes more liquid in nature, and less solid.

- indicates presence of gelatinase which allows gelatin to be used for energy and carbon source

67
Q

What is the purpose of the nitrate reduction test?

A

This test determines whether the microbe produces the enzymes nitrate reductase and nitrite reductase. If both are present then N2 gas is produced

68
Q

If there is a bubble and the solution did not change colors. indicates what for the nitrate reduction test.

A

the organism is not a fermenter but is able to completely reduce nitrate to nitrogen gas

69
Q

If there is no bubble present and the solution turns red after drops of reagents A and B, what is the result?

A

the organism is able to reduce nitrate to nitrite

70
Q

If reagents A, B and zinc are added and the solution turns red, what does this indicate?

A

nitrate reduction is not possible

71
Q

If reagents A, B and zinc are added and the solution remains yellow, what is the indication?

A

The nitrate is reduced to some other compound. test complete

72
Q

What is able to cause Beta hemolysis on a blood agar?

A
  • release of streptolysin O or sterptolysin S

- both of which are endotoxins

73
Q

Group A streptococcus are able to produce beta hemolysis via what compound?

A

streptolysin O and S, which clears the surface and under the surface of the agar

Microbiology (14 decks)

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