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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
What is the less common glycolytic pathway?
Entner-Doudoroff Pathway
26
What bacteria use the EDP pathway?
When they are restricted to this pathway as they are missing one or more of the enzymes required by the EMP pathway
27
Can organisms use both the EDP pathway and the EMP pathway?
Yes some archaea can switch between both pathways
28
What can not be used in the EMP pathway?
Carbohydrates so they are shunted in as 6-phosphogluconate or 2-keto-3-deoxy-6-phosphogluconate
29
What is the overall reaction of the EDP Pathway
Glucose + NADP+ + NAD+ + ADP + Pi --> 2 pyruvate + NADPH + 2H+ + NADH + ATP
30
What uses the EDP Pathway?
Obligate aerobes
31
Why do only obligate aerobes use the EDP Pathway?
Aerobes are not impaired by the lower ATP levels generated Most ATP is generated in the electron transport chain
32
What does "Pentose" refer to in the Pentose Phosphate Pathway
The production of 5-carbon intermediates
33
What Pathway does the PP Pathway work with?
EMP Pathway
34
What is the primary purpose of the Pentose Phosphate Pathway?
Generate NADPH and precursors for biosynthesis (anabolism)
35
Enzymes?
 Ribonucleotides  Deoxyribonucleotides  Aromatic amino acids (W, Y, F)  Other aromatic metabolites
36
Proteases
Break down proteins to peptides
37
Peptidases
Break down peptides to amino acids
38
Deaminases
Remove the amino group
39
What does EC stand for?
Enzyme commission number
40
EC 1
Oxidoreductases: transfer electrons from one molecule to another molecule
41
EC 2
Transferases: transfer a functional group from one molecule to another molecule (PO4, OH, CH3)
42
EC 3
Hydrolases: break covalent bonds using a molecule of water (have water in the equation/reaction)
43
EC 4
Lyases: break covalent bonds without water
44
EC 5
Isomerases: move functional groups within a molecule
45
EC 6
Ligases: join 2 molecules
46
EC 7
Translocases: moves specific solutes across a membrane
47
Why is recycling NADH such a problem?
Because both the EMP pathway and the EDP pathway produce it by consuming/absorbing NAD+
48
Why is NADH useful when growing anaerobically?
Provides reducing power for biosynthesis
49
Why is NADH a liability when growing anaerobically?
Need NAD+ for additional rounds of glycolysis
50
What is the solution to recycling NADH for the pathways?
Fermentation and Respiration
51
What is fermentation?
A metabolic process that uses an endogenous organic molecule as a terminal electron acceptor
52
What does fermentation start and end with?
Pyruvate, fermentation product
53
What is the purpose of fermentation?
Replenish NAD+ so that glycolysis can continue to produce a small but constant stream of ATP
54
What are the common types of fermentation?
Lactic acid, ethanol, and mixed acid
55
What enzyme is involved in Lactic acid fermentation?
Lactate dehydrogenase
56
What activity is involved in Lactic acid fermentation?
Reduces pyruvate to lactic acid
57
What products are involved in Lactic acid fermentation?
Latic acid and NAD+
58
What benefit to the microbe in Lactic acid fermentation?
Recycles NADH
59
What benefit to humans is there in Lactic acid fermentation?
Provides food with a tart taste and a longer shelf-life
60
What terminal electron acceptor is involved in Lactic acid fermentation?
Pyruvate
61
What fermentation product is involved in Lactic acid fermentation?
Lactid acid
62
What microbial examples are in Lactic acid fermentation?
 Lactobacillus sp.  Lactococcus sp.  Pediococcus sp.  Streptococcus sp.  Leuconostoc sp.
63
What enzymes are involved in Ethanol fermentation?
Pyruvate decarboxylase (PCD) Alcohol dehydrogenase (ADH)
64
What activities are involved in Ethanol fermentation?
PDC removes a carbon from pyruvate --> acetaldehyde + CO2 ADH reduces acetaldehyde --> ethanol + NAD+
65
What products are involved in Ethanol fermentation?
Ethanol and NAD+
66
What are the benefits to the microbe in Ethanol fermentation?
Recycles NADH
67
What is the benefit to humans in Ethanol fermentation?
Ethanol and CO2 (e.g. bread rising)
68
What is the terminal electron acceptor in Ethanol fermentation?
Acetaldehyde
69
What is the fermentation product in Ethanol fermentation?
Ethanol
70
What are some microbial examples in Ethanol fermentation?
 Zymomonas mobilis  Many yeasts (e.g. Saccharomyces cerevisiae)
71
What are the products of mixed acid fermentation?
Ethanol, Lactic acid, and Acetic acid
72
What are the benefits to the microbe of mixed acid fermentation?
Recycles NADH Provides another molecule of ATP
73
What is the terminal electron acceptor of mixed acid fermentation?
ATP
74
What are the microbial examples of mixed acid fermentation?
Enterobacteriaceae (Escherichia, Salmonella, Klebsiella, etc.)
75
Respiration
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
What are the components of Respiration?
Krebs cycle, Electron transport chain, and ATP Synthase
77
What are the purposes of the Krebs cycle in respiration?
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
Citrate
Fatty acids, sterols
79
Isocitrate
Glutamine, proline, arginine, glutamate, purines
80
Succinyl-CoA
Heme
81
Oxaloacetate
Aspartate, aspargine, pyrimdines
82
What is the purpose of NADH/FADH2?
Transfer electrons to the ETC
83
What does the electron transport chain do?
Reduced coenzymes transfer electrons to Complex 1
84
What happens when electrons move through the ETC?
Energy extracted with each transfer ENergy used to pump protons and establish a proton gradient
85
What is the purpose of ATP synthase?
Couples the kinetic energy of protons to the synthesis of ATP
86
What is catabolism in redox reactions?
Small controlled, oxidation steps?
87
Protons follow
Electrons in biological molecules
88
Reduction potential
Measure the tendency of a molecule to acquire electrons
89
Molecules with more negative electronegativity
Are better electron donors
90
Molecules with more positive electronegativity
Are better electrons acceptors
91
The energy released by the redox reaction is proportional to
The difference in reduction potential (Delta Eo') between the redox couples: Delta Eo' = Eo' (recipient) - Eo' (donor)
92
Interpretation of Redox reactions
A large (+) Delta Eo' indicates that the redox reaction is energetically favorable and that a great deal of energy is released
93
Nitrate (NO3-)
Nitrite (NO2-)
94
Nitrite (NO2-)
Dinitrogen (N2)
95
Sulfate (SO4-)
Hydrogen sulfide (H2S)
96
Elemental sulfur (So)
Hydrogen sulfide (H2S)
97
Ferric iron (FE3+)
Ferrous iron (Fe2+)
98
Fumarate (C4H2O4)
Succinate (C4H6O4)
99
What doe sit mean to have a less positive reduction potential than O2
Not as much energy is released Fewer protons are pumped per electron Less ATP is generated
100
What is the synthesis of ATP?
ADP + Pi -> ATP + H20 (strongly endergonic reaction)
101
Where does the energy come from to synthesize ATP?
Substrate level phosphorylation
102
What are some characteristics of the synthesis of ATP?
Enzymatically coupled reaction Coupling partner: high energy phosphorylated intermediate
103
What are some examples of ATP synthesis?
Glycolysis and Citric Acid Cycle
104
When can phosphate be transferred?
From any high energy compound to any lower energy compound
105
When can a phosphate be accepted?
Any low energy compound can accept a phosphate from a higher one
106
When is the energy of hydrolysis released?
Upon the removal of one phosphate group
107
Delts G =
Delta G (donor) + Delta G (recipient)
108
Oxidative phosphorylation characteristics
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
What enzyme is used in oxidative phosphorylation?
ATP synthase

Microbiology Unit 2 Exam (4 decks)

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