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Microbiology Unit 2 Exam > Metabolism: Gibb's Free Energy > Flashcards

Metabolism: Gibb's Free Energy Flashcards

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1
Q

Catabolic reactions

A

Breaking down reactions/molecules

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2
Q

What do catabolic reactions provide?

A

Building blocks necessary for anabolic reactions (amino acids, nucleic acids, fatty acids, vitamins, C HOPKINS CaFe)
Electrons

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3
Q

What is the purpose of electrons in catabolic reactions?

A

A source of energy for the synthesis of ATP

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4
Q

Anabolic reactions

A

Building up reactions

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5
Q

Gibbs free energy equation

A

Delta G = Delta H - (T*Delta S)

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6
Q

Delta G

A

Gibb’s free energy, a measure of the spontaneity of a reaction

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7
Q

What does a - Delta G mean?

A

Spontaneous, energy-yielding reaction (exergonic)

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8
Q

What does a + Delta G mean?

A

Non-spontaneous, energy-requiring reaction (endergonic)

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9
Q

Delta H

A

Enthalpy, a measure of the energy content of a substance

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10
Q

What does a - Delta H mean?

A

Heat releasing, exothermic reaction

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11
Q

What does a + Delta H mean?

A

Heat absorbing, endothermic reaction

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12
Q

Delta S

A

Entropy, a measure of the order of a substance

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13
Q

What does a - Delta S mean?

A

Decreased disorder, increased order

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14
Q

What does a + Delta S mean?

A

Increased disorder, decreased order (preferred)

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15
Q

The second law of thermodynamics

A

In every physical and chemical reaction, the universe always tends toward greater disorder; adds direction to every reaction

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16
Q

What does the second law of thermodynamics require for an endergonic reaction?

A

That endergonic reaction be coupled with a greater exergonic reaction to proceed

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17
Q

What is the most abundant organic molecule in the biosphere?

A

Glucose

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18
Q

What uses glycolytic pathways to obtain energy and carbon?

A

Chemoorganoheterotrophs

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19
Q

What is the most common glycolytic pathway?

A

Embden-Meyerhof-Parnas Pathway (EMP)

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20
Q

What is the overall reaction in the EMP Pathway?

A

Glucose + 2ADP + 2Pi + 2NAD+ –>
2 pyruvate + 2 ATP + 2NADH + 2H+

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21
Q

EMP pathway is not only for glucose

A

Other carbohydrates can be converted to various intermediates in the pathway and shunted in

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22
Q

What are the other molecules that the EMP pathway can use?

A

Galactose, Fructose, Mannose, Glycerol

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23
Q

What is the main objective of EMP Pathway

A

Partial oxidation of substrates, produces little ATP and NADH and prepares carbon (pyruvate) for entry into the Citric Acid Cycle/ Kelvin Cycle

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24
Q

What are the enzymes involved in the EMP Pathway?

A

 Hexokinase (EC 2): Transferase
 Glucose-6-phosphate Isomerase (EC 5): Isomerase
 Phosphofructokinase (EC 2): Transferase
 Aldolase (EC 4): Lyase
 Triosephosphate Isomerase (EC 5): Isomerase
 Glyceraldehyde-3-phosphate dehydrogenase (EC 1):
Oxidoreductase
 Phosphoglycerate kinase (EC 2): transferase
 Phosphoglycerate mutase (EC 5): Isomerase
 Enolase (EC 4): Lyase
 Pyruvate kinase (EC 2): transferase

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25
Q

What is the less common glycolytic pathway?

A

Entner-Doudoroff Pathway

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26
Q

What bacteria use the EDP pathway?

A

When they are restricted to this pathway as they are missing one or more of the enzymes required by the EMP pathway

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27
Q

Can organisms use both the EDP pathway and the EMP pathway?

A

Yes some archaea can switch between both pathways

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28
Q

What can not be used in the EMP pathway?

A

Carbohydrates so they are shunted in as 6-phosphogluconate or 2-keto-3-deoxy-6-phosphogluconate

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29
Q

What is the overall reaction of the EDP Pathway

A

Glucose + NADP+ + NAD+ + ADP + Pi –> 2 pyruvate + NADPH + 2H+ + NADH + ATP

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30
Q

What uses the EDP Pathway?

A

Obligate aerobes

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31
Q

Why do only obligate aerobes use the EDP Pathway?

A

Aerobes are not impaired by the lower ATP levels generated
Most ATP is generated in the electron transport chain

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32
Q

What does “Pentose” refer to in the Pentose Phosphate Pathway

A

The production of 5-carbon intermediates

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33
Q

What Pathway does the PP Pathway work with?

A

EMP Pathway

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34
Q

What is the primary purpose of the Pentose Phosphate Pathway?

A

Generate NADPH and precursors for biosynthesis (anabolism)

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35
Q

Enzymes?

A

 Ribonucleotides
 Deoxyribonucleotides
 Aromatic amino acids (W, Y, F)
 Other aromatic metabolites

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36
Q

Proteases

A

Break down proteins to peptides

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37
Q

Peptidases

A

Break down peptides to amino acids

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38
Q

Deaminases

A

Remove the amino group

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39
Q

What does EC stand for?

A

Enzyme commission number

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40
Q

EC 1

A

Oxidoreductases: transfer electrons from one molecule to another molecule

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41
Q

EC 2

A

Transferases: transfer a functional group from one molecule to another molecule (PO4, OH, CH3)

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42
Q

EC 3

A

Hydrolases: break covalent bonds using a molecule of water (have water in the equation/reaction)

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43
Q

EC 4

A

Lyases: break covalent bonds without water

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44
Q

EC 5

A

Isomerases: move functional groups within a molecule

45
Q

EC 6

A

Ligases: join 2 molecules

46
Q

EC 7

A

Translocases: moves specific solutes across a membrane

47
Q

Why is recycling NADH such a problem?

A

Because both the EMP pathway and the EDP pathway produce it by consuming/absorbing NAD+

48
Q

Why is NADH useful when growing anaerobically?

A

Provides reducing power for biosynthesis

49
Q

Why is NADH a liability when growing anaerobically?

A

Need NAD+ for additional rounds of glycolysis

50
Q

What is the solution to recycling NADH for the pathways?

A

Fermentation and Respiration

51
Q

What is fermentation?

A

A metabolic process that uses an endogenous organic molecule as a terminal electron acceptor

52
Q

What does fermentation start and end with?

A

Pyruvate, fermentation product

53
Q

What is the purpose of fermentation?

A

Replenish NAD+ so that glycolysis can continue to produce a small but constant stream of ATP

54
Q

What are the common types of fermentation?

A

Lactic acid, ethanol, and mixed acid

55
Q

What enzyme is involved in Lactic acid fermentation?

A

Lactate dehydrogenase

56
Q

What activity is involved in Lactic acid fermentation?

A

Reduces pyruvate to lactic acid

57
Q

What products are involved in Lactic acid fermentation?

A

Latic acid and NAD+

58
Q

What benefit to the microbe in Lactic acid fermentation?

A

Recycles NADH

59
Q

What benefit to humans is there in Lactic acid fermentation?

A

Provides food with a tart taste and a longer shelf-life

60
Q

What terminal electron acceptor is involved in Lactic acid fermentation?

A

Pyruvate

61
Q

What fermentation product is involved in Lactic acid fermentation?

A

Lactid acid

62
Q

What microbial examples are in Lactic acid fermentation?

A

 Lactobacillus sp.
 Lactococcus sp.
 Pediococcus sp.
 Streptococcus sp.
 Leuconostoc sp.

63
Q

What enzymes are involved in Ethanol fermentation?

A

Pyruvate decarboxylase (PCD)
Alcohol dehydrogenase (ADH)

64
Q

What activities are involved in Ethanol fermentation?

A

PDC removes a carbon from pyruvate –> acetaldehyde + CO2
ADH reduces acetaldehyde –> ethanol + NAD+

65
Q

What products are involved in Ethanol fermentation?

A

Ethanol and NAD+

66
Q

What are the benefits to the microbe in Ethanol fermentation?

A

Recycles NADH

67
Q

What is the benefit to humans in Ethanol fermentation?

A

Ethanol and CO2 (e.g. bread rising)

68
Q

What is the terminal electron acceptor in Ethanol fermentation?

A

Acetaldehyde

69
Q

What is the fermentation product in Ethanol fermentation?

A

Ethanol

70
Q

What are some microbial examples in Ethanol fermentation?

A

 Zymomonas mobilis
 Many yeasts (e.g. Saccharomyces cerevisiae)

71
Q

What are the products of mixed acid fermentation?

A

Ethanol, Lactic acid, and Acetic acid

72
Q

What are the benefits to the microbe of mixed acid fermentation?

A

Recycles NADH
Provides another molecule of ATP

73
Q

What is the terminal electron acceptor of mixed acid fermentation?

A

ATP

74
Q

What are the microbial examples of mixed acid fermentation?

A

Enterobacteriaceae (Escherichia, Salmonella,
Klebsiella, etc.)

75
Q

Respiration

A

A metabolic process in which electrons generated from glycolytic processing are passed through an electron transport system and onto an exogenous electron acceptor (O2)

76
Q

What are the components of Respiration?

A

Krebs cycle, Electron transport chain, and ATP Synthase

77
Q

What are the purposes of the Krebs cycle in respiration?

A

Fully oxidize substrates to maximize energy production
Generate a large number of reduced electron carriers (NADH, NADPH, FADH2)
Directly generates a little more ATP through substrate-level phosphorylation
Provide a source of small carbon molecules for biosynthesis

78
Q

Citrate

A

Fatty acids, sterols

79
Q

Isocitrate

A

Glutamine, proline, arginine, glutamate, purines

80
Q

Succinyl-CoA

A

Heme

81
Q

Oxaloacetate

A

Aspartate, aspargine, pyrimdines

82
Q

What is the purpose of NADH/FADH2?

A

Transfer electrons to the ETC

83
Q

What does the electron transport chain do?

A

Reduced coenzymes transfer electrons to Complex 1

84
Q

What happens when electrons move through the ETC?

A

Energy extracted with each transfer
ENergy used to pump protons and establish a proton gradient

85
Q

What is the purpose of ATP synthase?

A

Couples the kinetic energy of protons to the synthesis of ATP

86
Q

What is catabolism in redox reactions?

A

Small controlled, oxidation steps?

87
Q

Protons follow

A

Electrons in biological molecules

88
Q

Reduction potential

A

Measure the tendency of a molecule to acquire electrons

89
Q

Molecules with more negative electronegativity

A

Are better electron donors

90
Q

Molecules with more positive electronegativity

A

Are better electrons acceptors

91
Q

The energy released by the redox reaction is proportional to

A

The difference in reduction potential (Delta Eo’) between the redox couples: Delta Eo’ = Eo’ (recipient) - Eo’ (donor)

92
Q

Interpretation of Redox reactions

A

A large (+) Delta Eo’ indicates that the redox reaction is energetically favorable and that a great deal of energy is released

93
Q

Nitrate (NO3-)

A

Nitrite (NO2-)

94
Q

Nitrite (NO2-)

A

Dinitrogen (N2)

95
Q

Sulfate (SO4-)

A

Hydrogen sulfide (H2S)

96
Q

Elemental sulfur (So)

A

Hydrogen sulfide (H2S)

97
Q

Ferric iron (FE3+)

A

Ferrous iron (Fe2+)

98
Q

Fumarate (C4H2O4)

A

Succinate (C4H6O4)

99
Q

What doe sit mean to have a less positive reduction potential than O2

A

Not as much energy is released
Fewer protons are pumped per electron
Less ATP is generated

100
Q

What is the synthesis of ATP?

A

ADP + Pi -> ATP + H20 (strongly endergonic reaction)

101
Q

Where does the energy come from to synthesize ATP?

A

Substrate level phosphorylation

102
Q

What are some characteristics of the synthesis of ATP?

A

Enzymatically coupled reaction
Coupling partner: high energy phosphorylated intermediate

103
Q

What are some examples of ATP synthesis?

A

Glycolysis and Citric Acid Cycle

104
Q

When can phosphate be transferred?

A

From any high energy compound to any lower energy compound

105
Q

When can a phosphate be accepted?

A

Any low energy compound can accept a phosphate from a higher one

106
Q

When is the energy of hydrolysis released?

A

Upon the removal of one phosphate group

107
Q

Delts G =

A

Delta G (donor) + Delta G (recipient)

108
Q

Oxidative phosphorylation characteristics

A

Involves the formation of ATP as a result of the transfer of electrons from NADH or FADH2 to O2 by a series of electron carriers in the ETC

109
Q

What enzyme is used in oxidative phosphorylation?

A

ATP synthase

Microbiology Unit 2 Exam (4 decks)

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