Biochem - Metabolism (Part 1) Flashcards
1
Q
Fatty acid oxidation occurs in the _____ (mitochondria/cytoplasm), whereas fatty acid synthesis occurs in the _____ (mitochondria/cytoplasm).
A
Mitochondria; cytoplasm
2
Q
Glycolysis occurs in the _____ (mitochondria/cytoplasm), whereas the Krebs cycle occurs in the _____ (mitochondria/cytoplasm).
A
Cytoplasm; mitochondria
3
Q
Where in the cell are the enzymes of the hexose monophosphate shunt located?
A
In the cytoplasm
4
Q
Where in the cell does acetyl coenzyme A production occur?
A
In the mitochondria
5
Q
Protein synthesis occurs on the _____ (rough/smooth) endoplasmic reticulum, whereas steroid synthesis occurs on the _____ (rough/smooth) endoplasmic reticulum.
A
Rough; smooth
6
Q
Name the three pathways that occur in both the cytoplasm and the mitochondria.
A
Heme synthesis, the Urea cycle, and Gluconeogenesis; remember the mnemonic: HUGs take two
7
Q
Name four pathways that occur exclusively in the mitochondria.
A
- Fatty acid oxidation
- Acetyl-CoA production
- Krebs cycle
- Oxidative phosphorylation
8
Q
Describe the function of a kinase.
A
An enzyme that utilizes adenosine triphosphate to add high-energy phosphate group onto substrate
9
Q
Describe the function of a phosphorylase.
A
An enzyme that adds inorganic phosphate onto substrate without utilizing adenosine triphosphate
10
Q
Describe the function of a phosphatase.
A
An enzyme that removes phosphate group from substrate
11
Q
Describe the function of a dehydrogenase.
A
An enzyme that oxidizes substrate
12
Q
Describe the function of a carboxylase.
A
An enzyme that adds one carbon with biotin as a cofactor
13
Q
What is the rate-determining enzyme of de novo pyrimidine synthesis?
A
Carbamoyl phosphate synthetase II
14
Q
Carbamoyl phosphate synthetase II is the rate-limiting enzyme of which metabolic process?
A
De novo pyrimidine synthesis
15
Q
What is the rate-determining enzyme of de novo purine synthesis?
A
Glutamine-phosphoribosyl pyrophosphate amidotransferase
16
Q
Glutamine-phosphoribosyl pyrophosphate amidotransferase is the rate-limiting enzyme of which metabolic process?
A
De novo purine synthesis
17
Q
What is the rate-determining enzyme of glycolysis?
A
Phosphofructokinase-1
18
Q
Phosphofructokinase-1 is the rate-limiting enzyme of which metabolic process?
A
Glycolysis
19
Q
What is the rate-determining enzyme of gluconeogenesis?
A
Fructose-1,6- bisphosphatase
20
Q
Fructose-1,6- bisphosphatase is the rate-limiting enzyme of which metabolic process?
A
Gluconeogenesis
21
Q
What is the rate-determining enzyme of the tricarboxylic acid cycle?
A
Isocitrate dehydrogenase
22
Q
Isocitrate dehydrogenase is the rate-limiting enzyme of which metabolic process?
A
The tricarboxylic acid cycle
23
Q
What is the rate-determining enzyme of glycogen synthesis?
A
Glycogen synthase
24
Q
Glycogen synthase is the rate-limiting enzyme of which metabolic process?
A
Glycogen synthesis
25
What is the rate-determining enzyme of glycogenolysis?
Glycogen phosphorylase
26
Glycogen phosphorylase is the rate-limiting enzyme of which metabolic process?
Glycogenolysis
27
What is the rate-determining enzyme of the hexose monophosphate shunt?
Glucose-6-phosphate dehydrogenase
28
Glucose-6-phosphate dehydrogenase is the rate-limiting enzyme of which metabolic process?
The hexose monophosphate shunt
29
What is the rate-determining enzyme of fatty acid synthesis?
Acetyl-CoA carboxylase
30
Acetyl-CoA carboxylase is the rate-limiting enzyme of which metabolic process?
Fatty acid synthesis
31
What is the rate-determining enzyme of fatty acid oxidation?
Carnitine acetyltransferase I
32
Carnitine acyltransferase I is the rate-limiting enzyme of which metabolic process?
Fatty acid oxidation
33
What is the rate-determining enzyme of ketogenesis?
HMG-CoA synthase
34
HMG-CoA synthase is the rate-limiting enzyme of which metabolic process?
Ketogenesis
35
What is the rate-determining enzyme of cholesterol synthesis?
HMG-CoA reductase
36
HMG-CoA reductase is the rate-limiting enzyme of which metabolic process?
Cholesterol synthesis
37
What is the rate-determining enzyme of the urea cycle?
Carbamoyl phosphate synthetase I
38
Carbamoyl phosphate synthetase I is the rate-limiting enzyme of which metabolic process?
The urea cycle
39
What is the name of the molecule that contains adenine, ribose, three phosphoryl groups, and two phosphoanhydride bonds?
Adenosine triphosphate
40
In which two organs is adenosine triphosphate produced from the aerobic metabolism of glucose via the malate-aspartate shuttle?
Heart and liver
41
How many adenosine triphosphate molecules are produced from the aerobic metabolism of glucose via the malate-aspartate shuttle?
32
42
How many adenosine triphosphate molecules are produced from the aerobic metabolism of glucose via the glyceraldehyde-3-phosphate shuttle?
30; this occurs in the muscle
43
Where does the energy come from in order to proceed from substrate to product in energetically unfavorable reactions?
The hydrolysis of adenosine triphosphate can be coupled with energetically unfavorable reactions to produce enough net energy
44
What is the net gain of adenosine triphosphate molecules after a molecule of glucose has participated in anaerobic glycolysis?
Two; the NADH created cannot be used to generate energy without oxygen
45
A glucose molecule is metabolized to the level of pyruvate and lactate; is this process an anaerobic or aerobic process?
An anaerobic process; no oxygen has been used in this reaction
46
Name the three activated carriers of electrons.
NADH, NADPH, FADH2
47
What is the activated carrier for phosphoryl groups?
Adenosine triphosphate
48
What molecule donates methyl groups?
S-adenosylmethionine
49
Which activated carrier molecule donates aldehyde groups?
Thiamin pyrophosphate
50
Acyl groups are transported using which two activated carriers?
Coenzyme A and lipoamide
51
What compounds are used as single-carbon donors in various reactions?
Tetrahydrofolates
52
What vitamin is the donor of the carboxyl group used in many biochemical reactions in the body?
Biotin
53
What pathway produces NADPH?
The hexose monophosphate shunt
54
Which molecule is used in catabolic processes as an acceptor of reducing equivalents?
NAD+
55
Catabolic processes generally use _____ (NAD+/NADPH) as an electron acceptor, whereas anabolic processes generally use _____ (NAD+/NADPH) as an electron donor.
NAD+; NADPH
56
Name the three universal electron acceptors.
NAD+, NADP+, and FAD+
57
In which four metabolic processes is NADPH consumed?
Anabolic processes, respiratory burst, P450, glutathione reductase
58
What is the enzymatic reaction catalyzed by hexokinase and glucokinase?
Both enzymes phosphorylate glucose to form glucose-6-phosphate
59
In the liver, formation of glucose-6-phosphate is the first step of which 2 reactions?
Glycolysis and glycogen synthesis
60
Which two locations in the body contain high concentrations of glucokinase?
The liver and cells of the pancreas; hexokinase predominates in the rest of the body
61
Which enzyme has a higher Km: glucokinase or hexokinase?
Glucokinase; this enzyme has no feedback-inhibition loop with glucose-6-phosphate, because its job is to store excess energy after a meal
62
Which enzyme has a higher affinity for glucose: glucokinase or hexokinase?
Hexokinase; this enzyme has a feedback-inhibition loop with glucose-6-phosphate, because its job is just to keep the cells supplied with energy
63
Which enzyme has a higher Vmax: glucokinase or hexokinase?
Glucokinase; this enzyme has no feedback-inhibition loop with glucose-6-phosphate, because its job is to store excess energy after a meal (remember: **GLU**cokinase is a **GLU**tton; it has a high Vmax because it cannot be satisfied)
64
Which enzyme has a greater capacity to convert glucose to glucose-6-phosphate: glucokinase or hexokinase?
Glucokinase; this enzyme has no feedback-inhibition loop with glucose-6-phosphate, because its job is to store excess energy after a meal and buffer blood glucose
65
By what process does glucokinase sequester glucose in the liver to prevent blood glucose spikes after meals?
Phosphorylation
66
Which enzyme is induced by insulin: hexokinase or glucokinase?
Glucokinase
67
What is the effect of glucokinase on the blood glucose level?
By storing excess glucose in the liver, the liver can act as a buffer to regulate the blood glucose level
68
Where in the cell are the reactions that produce 2 pyruvate molecules from 1 glucose?
In the cytoplasm
69
In glycolysis, what enzyme catalyzes the formation of fructose-1,6 bisphosphate?
Phosphofructokinase-1
70
In glycolysis, what enzyme catalyzes the rate-limiting step?
Phosphofructokinase-1
71
Which molecules inhibit phosphofructokinase-1?
Adenosine triphosphate and citrate inhibit phosphofructokinase-1 since glycolysis is unnecessary in an energy-replete cell
72
In glycolysis, the reactions catalyzed by what five enzymes are irreversible?
Hexokinase, glucokinase, phosphofructokinase-1, pyruvate kinase, and pyruvate dehydrogenase
73
Is citrate an activator or an inhibitor of the enzyme that catalyzes the rate-limiting step in glycolysis?
Inhibitor
74
In glycolysis, fructose-2,6-bisphosphate _____ (increases/decreases) the production of fructose-1,6-bisphosphate from fructose-6-phosphate.
Increases
75
In glycolysis, is adenosine monophosphate an activator or an inhibitor of phosphofructokinase-1?
Activator
76
Name three compounds that decrease the activity of pyruvate dehydrogenase through negative feedback.
Adenosine triphosphate, NADH, and acetyl-CoA are inhibitors of pyruvate dehydrogenase; they are indicators that a cell is energy replete
77
In glycolysis, fructose-1,6-bisphosphate _____ (increases/decreases) the activity of pyruvate kinase.
Increases
78
What enzyme catalyzes the conversion of phosphoenolpyruvate to pyruvate during glycolysis?
Pyruvate kinase
79
In glycolysis, the formation of acetyl-CoA from pyruvate is catalyzed by what enzyme?
Pyruvate dehydrogenase
80
In the reaction that produces glucose-6-phosphate from D-glucose, is adenosine triphosphate produced or consumed?
Consumed
81
In the reaction that produces fructose-1,6-bisphosphate from fructose-6-phosphate, is adenosine triphosphate produced or consumed?
Consumed
82
In the reaction that produces 3-phosphoglycerate from 1,3-bisphosphoglycerate, is adenosine triphosphate produced or consumed?
Produced
83
In the reaction that produces pyruvate from phosphoenolpyruvate, is adenosine triphosphate produced or consumed?
Produced
84
In glycolysis, the formation of 3-phosphoglycerate from 1,3-bisphosphoglycerate is catalyzed by which enzyme?
Phosphoglycerate kinase
85
True of False? In glycolysis, the reaction catalyzed by phosphoglycerate kinase is reversible.
TRUE
86
What is the most potent activator of phosphofructokinase-1?
Fructose-2,6-bisphosphate
87
The enzyme phosphofructokinase 2 catalyzes which reaction?
The conversion of fructose-6-phosphate to fructose-2,6-bisphosphate
88
What enzyme converts fructose-1,6-bisphosphate (F1,6BP) into fructose-6-phosphate during gluconeogenesis?
Fructose bisphosphatase-1 (FB Pase-1)
89
Fructose bisphosphatase-2 catalyzes which reaction?
Conversion of fructose-2,6-bisphosphate into fructose-6-phosphate
90
What function do FBP-1 and FBP-2 have in common?
Both remove a phosphate group from their target; FBP-1 removes that from the 1 carbon of F1,6BP, while FBP-2 removes that from the 2 carbon of F2,6BP
91
What function do PFK-1 and PFK-2 have in common?
Both add a phosphate group to either the 1 carbon (in PFK-1) or the 2 carbon (in PFK-2) of fructose-6-phosphate
92
Which enzyme regulating the level of F2,6BP is active in the fed state?
Phosphofructokinase 2, increasing glycolysis and thus adenosine triphosphate creation for anabolic processes
93
Which enzyme regulating the level of F2,6BP is active in the fasting state?
Fructose bisphosphatase-2, increasing gluconeogenesis when glucose is needed for catabolic processes
94
In the fed state, does the cell perform glycolysis or gluconeogenesis? What enzyme is responsible?
When glucose is available, the body will perform glycolysis because PFK-2 is active and will increase the amount of F2,6BP
95
In the fasting state, does the cell perform glycolysis or gluconeogenesis? What enzyme is responsible?
The liver cell will perform gluconeogenesis because FB Pase-2 is active and will decrease the amount of F2,6BP
96
Glucagon has what effect on F26BP levels? By what mechanism?
Increases; increased protein kinase A
97
Insulin has what effect on F26BP levels? By what mechanism?
Insulin increases F26BP levels by activating PFK-2 through dephosphorylation, promoting glycolysis and inhibiting gluconeogenesis.
98
A patient with a genetic mutation in their glycolysis pathway is anemic; what is the likely etiology?
This is likely hemolytic anemia due to red blood cell swelling and lysis
99
Why does inhibition of the erythrocyte Na+/K+ adenosine triphosphatase cause hemolytic anemia?
Inability to transfer ions results in cell swelling and lysis
100
True or False? Red blood cells are able to metabolize glucose through oxidative phosphorylation.
False; red blood cells have no mitochondria, which are the site of oxidative phosphorylation
101
True or False? Red blood cells depend solely on glycolysis to produce adenosine triphosphate from glucose.
TRUE
102
What is the most common glycolytic enzyme deficiency?
Pyruvate kinase
103
How many enzymes make up the pyruvate dehydrogenase complex?
Three
104
How many cofactors are required for pyruvate dehydrogenase complex activity?
Five
105
A sick patient has rice water stools, vomiting, and garlic breath; what is the diagnosis?
Arsenic poisoning
106
How does arsenic interfere with pyruvate dehydrogenase?
Arsenic inhibits lipoic acid
107
What enzyme catalyzes the conversion of pyruvate to acetyl-CoA?
Pyruvate dehydrogenase complex
108
A(n) _____ (increase/decrease) in the NAD+/NADH ratio in a cell leads to increased activity of the pyruvate dehydrogenase complex.
Increase
109
A(n) _____ (increase/decrease) in the concentration of calcium in a cell leads to increased activity of the pyruvate dehydrogenase complex.
Increase
110
Which enzyme in the citric acid cycle has a similar structure to the pyruvate dehydrogenase complex and uses the same cofactors?
The -ketoglutarate dehydrogenase complex
111
Which cofactors are required for the activity of the pyruvate dehydrogenase complex?
Pyrophosphate (B1 [thiamine]), FAD (B2 [riboflavin]), NAD (B3 [niacin]), CoA (B5 [pantothenate]), and lipoic acid
112
What types of stimuli activate the pyruvate dehydrogenase complex?
Stimuli that indicate a deficit of energy (or adenosine triphosphate)
113
A(n) _____ (increase/decrease) in adenosine diphosphate in a cell leads to increased activity of the pyruvate dehydrogenase complex.
Increase; increased adenosine diphosphate indicates that the cell requires more adenosine triphosphate production in the tricarboxylic acid cycle
114
What substance causes the acid-base imbalance in patients with pyruvate dehydrogenase deficiency?
Lactic acid; patients have a lactic acidosis
115
Which substrates of the pyruvate dehydrogenase complex build up if the enzyme complex is deficient?
Pyruvate and alanine
116
How does pyruvate dehydrogenase deficiency present clinically?
With neurologic deficits such as lethargy, ataxia, and developmental delay
117
A patient with pyruvate dehydrogenase deficiency should have what type of diet?
Ketogenic; it will allow for energy generation with development of lactic acidosis
118
What are the only two purely ketogenic amino acids?
Lysine and leucine
119
Why is pyruvate dehydrogenase deficiency seen in alcoholics?
These individuals have a vitamin B1 deficiency, which is necessary to create active pyruvate dehydrogenase
120
In pyruvate metabolism, which enzyme catalyzes the conversion of pyruvate to alanine?
Alanine transaminase
121
In pyruvate metabolism, which enzyme converts pyruvate to lactate?
Lactate dehydrogenase
122
What enzyme converts pyruvate to acetyl-CoA?
Pyruvate dehydrogenase complex
123
In pyruvate metabolism, which enzyme catalyzes the conversion of pyruvate to oxaloacetate?
Pyruvate carboxylase
124
Which amino acid serves as a carrier of amino groups from muscle to liver?
Alanine
125
What four compounds can be formed from pyruvate in a single step?
Acetyl-CoA, lactate, alanine, and oxaloacetate
126
The conversion of pyruvate to lactate is the final step of which pathway?
Anaerobic glycolysis
127
Which cells in the body use anaerobic glycolysis as a major source of adenosine triphosphate?
Red blood cells, leukocytes, kidney medulla, testes, lens, and cornea
128
Pyruvate can be converted to what substance used to replenish intermediates during the citric acid cycle?
Oxaloacetate; can also be used for gluconeogenesis
129
Pyruvate is converted into which two molecules that can enter the tricarboxylic acid cycle?
Acetyl-CoA and oxaloacetate
130
What is the purpose of the Cori cycle?
Allows lactate formed in muscles to be used for gluconeogenesis in the liver
131
Which tissues create adenosine triphosphate in the Cori cycle? Which tissues consume adenosine triphosphate?
Muscles and red blood cells; liver
132
Does the Cori cycle facilitate aerobic or anaerobic glycolysis?
Anaerobic; the Cori cycle facilitates the metabolism of lactate
133
What is the net gain or loss of adenosine triphosphate molecules during the Cori cycle?
There is a net loss of four adenosine triphosphate molecules
134
A runner is found to be producing large amounts of lactate in his leg muscles during training; what process is likely occurring in the liver at the same time?
Gluconeogenesis; he is performing anaerobic glycolysis in his legs and replenishing the glucose supply in his liver via the Cori cycle
135
During the Cori cycle, ______ (pyruvate/lactate) returns to the liver to undergo gluconeogenesis.
Lactate
136
The Cori cycle preferentially supplies energy to the ______ (muscles/liver) in spite of energetically unfavorable reactions in the ______ (muscles/liver).
Muscles; liver
137
How many NADH molecules are produced during one turn of the citric acid cycle?
Three
138
How many FADH2 molecules are produced during one turn of the citric acid cycle?
One
139
How many carbon dioxide molecules are produced during one turn of the citric acid cycle?
Two
140
In the citric acid cycle, adenosine triphosphate _____ (activates/inhibits) citrate synthase.
Inhibits; this is a negative feedback mechanism for when the cell is energy replete
141
How many guanosine triphosphate molecules are produced during one turn of the citric acid cycle?
One
142
In the citric acid cycle, adenosine triphosphate is an _____ (activator/inhibitor) of isocitrate dehydrogenase, whereas adenosine diphosphate is an _____ (activator/inhibitor).
Inhibitor; activator; the mechanism ensures that the cell produces adenosine triphosphate only when required
143
How many adenosine triphosphate molecules are produced during one turn of the citric acid cycle?
12
144
How many adenosine triphosphate molecules are produced from one molecule of glucose by the citric acid cycle?
24
145
How many FADH2 molecules are produced from one molecule of glucose by the citric acid cycle?
Two
146
How many carbon dioxide molecules are produced from one molecule of glucose by the citric acid cycle?
Four
147
How many guanosine triphosphate molecules are produced from one molecule of glucose by the citric acid cycle?
Two
148
In the citric acid cycle, -ketoglutarate dehydrogenase is _____ (inhibited/activated) by the high-energy compounds NADH and adenosine triphosphate.
Inhibited
149
In the citric acid cycle, adenosine triphosphate, acetyl-CoA, and NADH are _____ (inhibitors/activators) of pyruvate dehydrogenase.
Inhibitors
150
What intermediate of the tricarboxylic acid cycle provides negative feedback to -ketoglutarate dehydrogenase to inhibit its function?
Succinyl-CoA
151
In the citric acid cycle, the production of -ketoglutarate, succinyl-CoA, and oxaloacetate from their precursors produces which high-energy molecule?
NADH
152
Where in the cell does the tricarboxylic acid cycle take place?
The mitochondria
153
In the citric acid cycle, the conversion of oxaloacetate to citrate is catalyzed by what enzyme?
Citrate synthase
154
In the citric acid cycle, the conversion of isocitrate to -ketoglutarate is catalyzed by what enzyme?
Isocitrate dehydrogenase
155
In the citric acid cycle, which enzyme catalyzes the conversion of -ketoglutarate to succinyl-CoA?
The -ketoglutarate dehydrogenase complex
156
Name the intermediates of the citric acid cycle.
**C**itrate, **I**socitrate, a-**K**etoglutarate, **S**uccinyl-CoA, **S**uccinate, **F**umarate, **M**alate, and **O**xaloacetate (remember: **C**itrate **I**s **K**reb's **S**tarting **S**ubstrate **F** or **M**aking **O**xaloacetate)
157
The formation what two substances during the citric acid cycle involve the release of carbon dioxide?
-Ketoglutarate and succinyl-CoA
158
What step of the citric acid cycle produces guanosine triphosphate?
The conversion of succinyl-CoA into succinate
159
What step of the citric acid cycle produces FADH2?
The conversion of succinate into fumarate
160
True or False? The enzymes of the citric acid cycle are generally inhibited by high-energy compounds such as adenosine triphosphate or NADH.
TRUE
161
Name four enzymes in the tricarboxylic acid cycle whose actions are irreversible.
Pyruvate dehydrogenase, citrate synthase, isocitrate dehydrogenase, and -ketoglutarate dehydrogenase
162
Electrons carried by NADH created in glycolysis and the tricarboxylic acid cycle may enter the mitochondria via which two shuttles?
Malate-aspartate shuttle or glycerol-3-phosphate shuttle
163
How many adenosine triphosphate molecules can be produced from one NADH molecule during oxidative phosphorylation?
Three
164
How many adenosine triphosphate molecules can be produced from one FADH2 molecule during oxidative phosphorylation?
Two
165
Which complex in the electron transfer chain receives electrons carried by NADH?
Complex I
166
Which complex in the electron transfer chain receives electrons carried by FADH2?
Complex II (succinate dehydrogenase)
167
Why does FADH2 produce fewer molecules of adenosine triphosphate than NADH?
It enters the electron transport chain at a lower energy level than NADH on complex II rather than I
168
How is the energy of the electron transport chain converted into adenosine triphosphate?
By creation of a proton gradient
169
What molecule ultimately accepts electrons from the electron transport chain?
Oxygen
170
What is the mechanism by which oligomycin interrupts adenosine triphosphate production?
Oligomycin directly inhibits mitochondrial adenosine triphosphate synthase
171
How does the pesticide rotenone block adenosine triphosphate synthesis?
Via direct inhibition of electron transport
172
What happens to the proton gradient in the mitochondria when adenosine triphosphate synthase is inhibited by oligomycin?
It increases, but protons cannot be released, causing the electron transport chain to halt and decreased adenosine triphosphate formation
173
How does the poison cyanide block adenosine triphosphate synthesis?
Via direct inhibition of electron transport
174
How does the gas carbon monoxide block adenosine triphosphate synthesis?
Via direct inhibition of electron transport
175
Poisons that directly inhibit the electron transport chain lead to a(n) _____ (increased/decreased) proton gradient in the mitochondria.
Decreased
176
Regarding oxidative phosphorylation, name three examples of uncoupling agents that will block adenosine triphosphate production.
2,4-Dinitrophenylhydrazine (2,4-DNP), aspirin, thermogenin
177
Regarding oxidative phosphorylation, 2,4-dinitrophenylhydrazine _____ (increases/decreases) the permeability of the mitochondrial membrane.
Increases
178
Regarding oxidative phosphorylation, electron transport inhibitors _____ (increase/decrease) the proton gradient.
Decrease
179
When acting as an uncoupling agent, aspirin _____ (increases/decreases) the proton gradient in the mitochondria.
Decreases; because of increased membrane permeability, protons are not forced through adenosine triphosphate synthase
180
What is the effect of thermogenin on oxygen use, adenosine triphosphate production, and heat generation?
* Oxygen use: Increases
* Adenosine Triphosphate (ATP) Production: Decreases
* Heat generation: Increases
181
Why does adenosine triphosphate production decrease when the mitochondrial membrane is disturbed?
The loss of the proton gradient means that there is no energy to drive adenosine triphosphate synthase
182
What is the action of an uncoupling agent on the mitochondrial membrane?
These increase the permeability of the membrane, decreasing the proton gradient
183
Does disruption of the proton gradient by an uncoupling agent cause electron transport to stop?
No; electron transport continues, but the protons moved across the membrane are free to return down the gradient without producing adenosine triphosphate
184
What is the result of an uncoupling agent on mitochondrial oxygen consumption?
There is increased oxygen consumption, because electron transport continues in an attempt to maintain the proton gradient
185
To produce adenosine triphosphate, protons must flow down their gradient from the _____ across the inner mitochondrial membrane to the \_\_\_\_\_.
Intermembranous space; mitochondrial matrix
186
In gluconeogenesis, what reaction is catalyzed by pyruvate carboxylase?
The conversion of pyruvate into oxaloacetate
187
Is pyruvate carboxylase found in the mitochondria or in the cytosol?
The mitochondria
188
Is phosphoenolpyruvate carboxykinase found in the mitochondria or in the cytosol?
The cytosol
189
In gluconeogenesis, what enzyme catalyzes the conversion of oxaloacetate into phosphoenolpyruvate?
Phosphoenolpyruvate carboxykinase
190
In gluconeogenesis, what is the name of the enzyme that catalyzes the reaction of fructose-1,6-bisphosphate to fructose-6-phosphate?
Fructose-1,6-bisphosphatase
191
In gluconeogenesis, does phosphoenolpyruvate carboxykinase require adenosine triphosphate or guanosine triphosphate?
Guanosine triphosphate
192
True or False? Gluconeogenesis occurs in skeletal muscle.
False; muscle does not contain the enzymes needed for gluconeogenesis
193
\_\_\_\_\_ (Odd/Even)-chain fatty acids yield propionyl-CoA during metabolism, which can produce new glucose; while _____ (odd/even)-chain fatty acids only yield acetyl-CoA equivalents.
Odd; even
194
In gluconeogenesis, what reaction is catalyzed by glucose-6-phosphatase?
The conversion of glucose-6-phosphate into glucose
195
A deficiency of gluconeogenic enzymes leads to what condition?
Hypoglycemia
196
Which cofactors are required by the enzyme pyruvate carboxylase?
Biotin and adenosine triphosphate
197
Name four enzymes in gluconeogenesis whose actions are irreversible.
**P**yruvate carboxylase, **P**EP carboxykinase, **F**ructose-1,6-bisphosphatase, **G**lucose-6-phosphatase (remember: **P**athway **P**roduces **F**resh **G**lucose)
198
What is the expected presenting sign of von Gierke's disease, which is a deficiency of glucose-6-phosphatase in the liver?
Hypoglycemia due to inability to perform gluconeogenesis
199
What is the primary location of gluconeogenesis in the body?
This process occurs mostly in the liver
200
Which small molecule can produce glucose after fatty acid metabolism: acetyl-CoA or propionyl-CoA?
Propionyl-CoA; acetyl-CoA cannot undergo gluconeogenesis
