Unit 3 Flashcards
(159 cards)
1
Q
__________ pathways can be either anabolic or catabolic, depending on the energy conditions of the cell.
A
Amphibolic
2
Q
In aerobic organisms, the ultimate acceptor of electrons is ______.
A
O2
3
Q
In aerobic metabolism, the product of oxidation of carbon containing fuels is ______.
A
CO2
4
Q
The electron carrier, NADH, is derived from the _________ vitamin
A
niacin
5
Q
FAD is an electron carrier that is derived from the vitamin ________.
A
riboflavin, B2
6
Q
Acetyl-Coenzyme A is derived from what vitamin?
A
pantothenate
7
Q
Biotin is derived from what vitamin?
A
Biotin
8
Q
Tetrahydrofolate is derived from what vitamin?
A
folate
9
Q
How is metabolism controlled?
A
amount of enzyme
catalytic enzyme activity
substrate accessibility
10
Q
What is unique to ATP in comparison to Acetyl CoA?
A
ATP carries phosphate with high transfer potential.
11
Q
What is unique to Acetyl CoA in comparison to ATP?
A
Acetyl CoA carries acetyl with high transfer potential.
12
Q
What do acetyl coA and ATP have in common?
A
Both are activated carriers that are common in several pathways.
13
Q
What are the two reasons that glucose is a common metabolic fuel used by living organisms?
A
It has a stable ring structure and is unlikely to glycosylate proteins
It has been found as a monosaccharide under prebiotic conditions.
14
Q
What are the purposes of phosphorylating glucose in cytosol?
A
Trap glucose in cell
Destabilize glucose and facilitate next series of metabolic steps
15
Q
What reaction is catalyzed by aldolase?
A
reversible cleavage of F-1,6 to DHAP and GAP
16
Q
What is the function of a thioester intermediate such as the one formed from GAP?
A
allows the two-step reaction to be coupled so the reaction, the energetically unfavorable phosphorylation, can proceed.
17
Q
What is substrate-level phosphorylation?
A
ATP synthesis when the phosphate donor is a substrate with high-phosphoryl-transfer potential
18
Q
What type of enzyme catalyzes the intramolecular shift of a chemical group?
A
mutase
19
Q
What are the primary metabolic fates of pyruvate?
A
ethanol, lactate, and acetyl CoA
20
Q
Lactose intolerance is caused by a deficiency of
A
lactase
21
Q
Fructose from sugar or corn syrup and galactose from milk sugar are converted to what?
A
Glycolytic intermediates
22
Q
During exercise, glycolysis is stimulated by a what?
A
feed-forward stimulation of pyruvate kinase
23
Q
Biotin is a _______ for the pyruvate carboxylase reaction.
A
cofactor
24
Q
The phosphoric donor in the formation of phosphoenolpyruvate is what?
A
GTP
25
The phosphorylation of glucose 6-phosphate takes place in which cellular location?
endoplasmic reticulum lumen
26
High levels of ATP and citrate do what?
indicate a high-energy-well-fed state
promote gluconeogenesis
inhibits glycolysis
27
PFK is a highly regulated enzyme. What is the inhibitor of PFK?
citrate
28
The major site of gluconeogenesis is in which tissue?
liver
29
High blood sugar after a meal ________ the level of insulin released by the pancreas.
increases
30
Insulin resistance is a hallmark of what?
Type 2 diabetes
31
Lactate produced in muscle tissue is converted to _______ by _________.
glucose by the cori cycle
32
How many high energy phosphate bonds are expended to make one glucose in gluconeogenesis?
6
33
The citric acid cycle is also known as what?
Krebs cycle and tricarboxylic acid cycle
34
Acetyl CoA is what?
The activated form of acyl groups that fuels the citric acid cycle
35
Which enzyme is responsible for the following reaction?
| Pyruvate + CoA + NAD+ --> Acetyl CoA + NADH + H+ CO2
pyruvate dehydrogenase complex
36
What are the steps involved in the conversion of pyruvate to acetyl CoA?
decarboxylation, oxidation, transfer to CoA
37
Pyruvate dehydrogenase is ________ when ATP-ADP ratios are high.
inhibited
38
Approximately how many ATP or GTP equivalentes are produced during one turn of the citric acid cycle?
10
39
In which step of the citric acid cycle is FADH2 formed?
conversion of succinate to fumarate
40
In which reaction is ATP directly formed in the citric acid cycle?
conversion of succinyl CoA to succinate
41
Formation of citrate from acetyl CoA and oxaloacetate is a __________ reaction.
condensation
42
What molecule initiates the citric acid cycle by reacting with oxaloacetate?
acetyl coA
43
Which of the following does not participate in, nor is a component of, the electron-transport chain? Coenzyme A, nonheme iron-sulfur protein, Coenzyme Q, cytochrome C1
Coenzyme A
44
Electron flow down the ETC leads to what?
Transport of protons across inner mitochondrial membrane from inside the matrix to the intermembrane space
45
Coenzyme Q is also called
ubiquinone
46
Which ETC complex does not pump protons?:
Complex II
47
What is a cytochrome?
protein that transfers e- and contains a heme prosthetic group
48
The Q cycle does what?
transfers e- from a two-electron carrier to a one-electron carrier
49
What pathologic conditions result from free-radical injury?
Emphysema, Parkinson's, diabetes, atherogenesis
50
Which enzyme catalyzes reductions of O2?
Cytochrome C oxidase
51
How is light used in photosynthesis?
light is used to generate high-energy e- with great reducing potential
52
Light absorbed by a chlorophyll causes what?
an electron to move from ground to excited state
53
What type of gradient is critical to ATP formation by oxidative phosphorylation?
proton
54
How many ATP molecules are made by oxidative phosphorylation out of a maximum yield of how many ATP molecules?
26 out of 30
55
The F1 component of ATP synthase is composed of what?
3 alpha subunits, 3 beta subunits, 1 delta subunit
56
The 3 beta subunits of the F1 component can exist in what forms?
Open, loose, and tight
57
Proton motive force consists of a:
chemical and proton gradient
58
The ATPase subunit embedded in the inner mitochondrial membrane is the what?
F0 subunit
59
The rate of oxidative phosphorylation is determined by the need for what?
ATP
60
What is the driving force for the ATP-ADP translocase?
membrane potential from electron transport
61
What is the net ATP obtained from 1 cytoplasmic NADH when it is oxidized by the ETC, using the glycerol 3-phosphate shuttle?
1.5
62
Proton gradients power what?
Active transport, NADPH synthesis, and electron potential
63
The major sites of glycogen storage are where?
liver and skeletal muscle
64
glycogen phosphorylase
key regulatory enzyme in glycogen degredation
65
How is phosphorylase b converted into phosphorylase a?
through the addition of a phosphate to a serine residue
66
What are the two critical hormones that signal for glycogen breakdown?
glucagon and epinephrine
67
What is required to remove branches in glycogen?
debranching and transferase enzymes
68
Which enzyme is required to synthesize alpha-1,4-glycosidic bonds in glycogen?
Glycogen synthase
69
The _________ creates a 1,4-glycosidic bond.
glycogen synthase
70
The enzyme that begins the kinase cascade activating glycogen degradation is what?
PKA
71
After exercise, muscle cell glycogen metabolism is regulated by what?
protein phosphatase 1
72
Which of the following occur after a carbohydrate-rich meal?
Blood-glucose levels increase, leading to glycogen storage in the liver
73
___________ is the principle carbohydrate in living systems
Glucose
74
The product of aerobic glycolysis is _________.
pyruvate
75
The substance ________ must be regenerated for glycolysis to proceed in either aerobic or anaerobic conditions
NAD+
76
An allosteric activator of glycolysis is ________
AMP
77
Glycolysis produces a net of ____ moles of ATP per 1 mole of glucose
2
78
The key regulatory enzyme for glycolysis is _______.
PFK
79
_________ are enzymes that catalyze the transfer of a phosphoryl group from ATP to an acceptor.
Kinases
80
In alcoholic fermentation, the decarboxylation of pyruvate requires a coenzyme that contains the vitamin _______
B1
81
A potent allosteric activator of liver phosphofructokinase is ________, which is produced from fructose-6-phosphate by the PFK2
fructose-2,6-bisphosphate
82
_________ mediate the thermodynamically downhill movement of glucose across plasma membranes
Glucose transporters
83
Insulin release from pancreatic β cells is regulated by __________.
ATP levels in the cell
84
How is glycolysis maintained under anaerobic conditions?
Pyruvate is reduced to either lactate or ethanol while NADH is oxidized to regenerate NAD+ in the fermentation process.
85
How does pyruvate kinase regulation occur?
When ATP is found in high concentrations, it allosterically inhibits pyruvate kinase. When cell energy is low and intermediates are high, feed-forward activation of pyruvate-kinase by fructose 1,6-bisphosphate occurs to activate glycolysis.
86
The process by which noncarbohydrate precursor molecules are converted into glucose is ____________.
gluconeogenesis
87
The stores of glucose are enough to support metabolism of a person for ________.
one day
88
The major tissue in which gluconeogenesis takes place is the _______.
liver
89
The conversion of glucose 6-phosphate to glucose takes place in this part of the cell: ________.
lumen of endoplasmic reticulum
90
The reaction that uses GTP and not ATP as its high-phosphoryl-transfer potential donor is ________.
PEP carboxylase
91
The compound _____ activates glycolysis and inhibits gluconeogenesis via conversion of fructose 1,6-bisphosphate.
fructose 2,6-bisphosphate
92
_____ controls the synthesis and degradation of fructose 2,6-bisphosphate.
PFK2
93
______: An intermediate that is decarboxylated and phosphorylated to produce phosphoenolpyruvate.
Oxaloacetate
94
_______: This essential nutrient is required for the carboxylation of pyruvate in humans.
Biotin
95
The _______ cycle is responsible for converting muscle lactate into glucose in the liver.
Cori
96
Glycerol from fats is modified first by glycerol kinase and then a second enzyme to enter gluconeogenesis at the intermediate ____________.
DHAP
97
What are the key glycolytic enzymes and how does gluconeogenesis overcome these enzymes?
pyruvate kinase: pyruvate carboxylase and PEP kinase
PRK: fructose 1,6-bisphophotase
hexokinase: glucose 6-phosphate
98
How does the liver restore glucose levels for active muscles?
Lactate conversion to glucose by the Cori Cycle
99
What is glycolysis activated by?
Fructose 2,6-bisphosphotase, AMP, and Fructose-1,6-bisphosphotase
100
What is glycolysis inhibited by?
ATP, alanine, citrate, and protons
101
What is gluconeogenesis activated by?
citrate and acetyl coA
102
What is gluconeogenesis inhibited by?
Fructose-2,6-bisphosphotase, AMP, and ADP
103
The activated carrier of acyl groups is _____________.
coenzyme A
104
In the presence of oxygen, pyruvate is converted to ______________.
acetyl CoA
105
What reaction serves to link glycolysis and the citric acid cycle?
Oxidative Decarboxylation of pyruvate to acetyl coA; Pyruvate + CoA + NAD+ → Acetyl CoA + NADH + H++ CO2
106
_______ is a large, multi-subunit enzyme complex that links glycolysis and the citric acid cycle under aerobic conditions.
Pyruvate dehydrogenase
107
PDH is inactivated when the enzyme _____.
is phosphorylated
108
_______ is caused by a deficiency in vitamin B1.
Beriberi
109
The function of the citric acid cycle is to _______ high-energy electrons
harvest
110
____________: The product found by the condensation of oxaloacetate and acetyl CoA.
Citrate
111
The intermediate between citrate and isocitrate is____.
cis-aconitate
112
_________: This citric acid cycle intermediate is at both the beginning and the end of the citric acid cycle.
Oxaloacetate
113
The product of the complete oxidation of carbon in the citric acid cycle is _________.
carbon dioxide
114
_______ are the key control points of the citric acid cycle.
Isocitrate dehydrogenase and alpha ketoglutarate dehydrogenase
115
_________: The name applied to metabolic reactions that replenish the citric acid cycle intermediates that are depleted because they were used for biosynthesis.
Anapleurotic
116
_______ are where oxidative phosphorylation occurs in eukaryotes.
Mitochondria
117
____________ is an ATP-generating process in which an inorganic substance such as oxygen serves as the ultimate electron acceptor
Respiration
118
The electron carrier ________ is a derivative of quinone and has an isoprenoid tail.
coenzyme Q
119
The citric acid cycle enzyme _______ is also part of an electron-transport complex.
succinate dehaydrogenase
120
Complex _______also know as NADH-Q oxidoreductase accepts electrons from NADH.
1
121
_________ is the complex that is not a proton pump
Complex II
122
A strong oxidizing agent has a strong tendency to __________ (accept, donate) electron(s).
accept
123
_______ are the result of uncontrolled electron transfer to oxygen
Oxygen radicals
124
In the cytochrome c oxidase reaction ______ protons are removed from the matrix.
8
125
In the overall stoichiometry of the light reactions, eight photons of light generate ____ molecules of ATP.
3
126
The primary photoreceptor in the chloroplasts of green plants is ____.
chlorophyll
127
Photosystem I generates biosynthetic reducing power in the form of ________
NADPH
128
Photosystem II replenishes the ________ of photosystem I while generating a __________ that is used to synthesize _____.
electrons
proton gradient
ATP
129
In the light reactions of photosynthesis, the cooperation between photosystem I and photosystem II creates a flow of electrons from H2O to __________.
NADP+
130
The rotation of the _________, driven by proton gradient, powers ATP synthesis
c ring
131
ADP transport into the mitochondria is coupled to the export of ____
ATP
132
Dihydroxyacetone phosphate is part of the __________ shuttle.
glycerol 3-phosphate
133
The number of ATP molecules produced by the transfer of electrons from NADH.
2.5
134
The membrane protein _____ couples the entry of ADP into the mitochondrial matrix with the exit of ATP.
ADP–ATP translocase
135
______ is a molecular assembly in the inner mitochondrial membrane that carries out the synthesis of ATP.
ATP synthase
136
Which form of the ATPase subunits is responsible for phosphorylation of ADP
tight
137
The proton gradient generated from the oxidation of NADH and FADH2 is called the __________.
proton-motive force
138
The F0 portion of ATP synthase contains the _____.
proton channel
139
Which form of the ATP synthase subunits is responsible for trapping nucleotides in the subunit β?
loose
140
The oxidative phase of the pentose phosphate pathway produces ______, which is required for lipid biosynthesis.
NADPH
141
The net result in sugars of the nonoxidative phase of the pentose phosphate pathway is the conversion of three ____into two _____and one _____.
pentoses
hexoses
triose
142
_______ is the enzyme at the committed step of the pentose phosphate pathway.
Glucose 6-phosphate dehydrogenase
143
________ is the key source of biosynthetic reducing equivalents.
The pentose phosphate pathway
144
The two key components required for growth are _____ and biochemical reducing powers.
ribose sugars
145
The second phase of the pentose phosphate pathway:
A) includes a 2-carbon molecule.
B) utilizes transketolases and a transaldolase
C) is the nonoxidative interconversion of a variety of sugars.
D) Requires ATP.
E) B and C.
E
146
In mode two of the pentose phosphate pathway:
A) the needs for NADPH and ribose 5-phosphate are balanced,
B) much more NADPH than ribose 5-phosphate is required.
C) more ribose 5-phosphate than NADPH is required.
D) NADPH and CO2 are required.
E) excess NAD+is required. .
A
147
In mode one of the pentose phosphate pathway:
A) the needs for NADPH and ribose 5-phosphate are balanced,
B) much more NADPH than ribose 5-phosphate is required.
C) more ribose 5-phosphate than NADPH is required.
D) NADPH and CO2 are required.
E) excess NAD+is required. .
C
148
Glutathione:
A) Helps prevent damage by reactive oxygen species
B) Requires NADH to maintain adequate levels
C) Is converted to its reduced form by NADPH
D) All of the above.
E) A and C.
E
149
```
The most important regulatory factor of the pentose phosphate pathway is:
A) ATP levels
B) ADP levels
C) NADPH levels
D) NAD+ levels.
E) None of the above.
```
E
150
____: Most of the glucose residues in glycogen are linked by this type of bond
α-1,4-glycoside
151
The ___________ enzyme catalyzes the phosphorylation of glycogen phosphorylase
phosphorylase kinase
152
The hormone ___________ signifies the starved or low glucose state.
glucagon
153
The _______ enzyme serves as the glucose “sensor” enzyme in liver cells
phosphorylase
154
_______ markedly increases glycogen breakdown in muscle by initiating a cAMP signal-transduction cascade.
Epinephrine
155
The hydrolysis catalyzed by α-1,6-glucosidase releases a(n)_______ molecule.
free glucose
156
_______is the monomer that is used to extend the chain in glycogen synthesis.
UDP-glucose
157
The complete oxidation of a glucose residue from glycogen produces________ ATP
31?
158
________ is the key regulatory enzyme in glycogen synthesis
Glycogen synthase
159
_______ shifts glycogen metabolism from the degradation mode to the synthesis mode.
Protein phosphatase 1 (PP1)
