Exam 3 Problem Roulette Flashcards
Where in the cell does Glycolysis take place in mammals?
In the Cytosol, since the enzymes are soluble
Which of the following is NOT an important catabolic product of pyruvate formed by glycolysis (i.e. what are the fates of pyruvate from glycolysis?)?
Glucose
Acetyl-CoA
Ethanol plus carbon dioxide
Lactate
Glucose
How many hexose phosphates are generated from 18 pentose phosphates during the non-oxidative phase of the Pentose Phosphate pathway?
9
6
15
18
3
15
Select the TRUE statement.
Gluconeogenesis in humans
Can take fatty acids to glucose.
helps decrease blood glucose after a carbohydrate-rich lunch
Is activated by the hormone insulin
requires PFK-1.
Cannot take acetyl CoA to glucose
Cannot take acetyl CoA to glucose
How many ATP molecules are required to convert one Glucose molecule to two 1,3-bisphosphoglycerate molecules?
2
1
8
None, ADP is required
4
2
What is the substrate of glycogen synthase for glycogen synthesis (that is, making glycogen longer)?
Glucose 1-phosphate
Glucose
Glucose 6-phosphate
Glucose 1,3-bisphosphate
UDP-glucose
UDP-glucose
The reaction in glycolysis that converts a ketose form to an aldose form is catalyzed by:
Phosphohexose isomerase
Phosphoglycerate mutase
Pyruvate kinase
Aldolase
Triose phosphate isomerase
Triose phosphate isomerase
The conversion of glucose-6-phosphate to ribulose-5-phosphate involves:
Hydrolysis of glucose-6-phosphate
Reduction of NADP+
Isomerization of glucose-6-phosphate
Carboxylation of glucose-6-phosphate
Reduction of glucose-6-phosphate
Reduction of NADP+
When a free glucose molecule first enters a cell (via the glucose transporter), the most likely first reaction catalyzed is:
Dehydration generating fructose
Phosphorylation of the C6 carbon using ATP
Isomerization into fructose
Phosphorylation of the C1 carbon using ATP
Dehydrogenation generating NADH
Phosphorylation of the C6 carbon using ATP
Glycolysis conserves metabolic energy in two different molecules. What is the correct pair of molecules and their net amounts produced by glycolysis?
4 ATP + 2 NADPH
2 ATP + 2 NADH
2 ATP + 4 NADH
4 ATP + 2 NADH
2 ATP + 2 NADPH
2 ATP + 2 NADPH
Which of the below helps convert glucose into a reactant for glycogen synthase?
cyclic AMP
CTP
GTP
UTP
ATP
UTP
The purpose of the oxidative phase of the pentose phosphate pathway is to:
oxidize glucose 6P, reduce NAD+, and as a result help generate energy (ATP) through oxidative phosphorylation
convert 6 ribose phosphates to 5 hexose phosphates
facilitate the Cori cycle.
provide intermediates for the citric acid cycle.
generate pentoses for the synthesis of nucleotides and nucleic acids.
generate pentoses for the synthesis of nucleotides and nucleic acids.
The electron acceptor in the steps that convert pyruvate to ethanol is:
pyruvate.
acetaldehyde.
NAD+.
TPP
ethanol.
acetaldehyde.
Which reaction of Glycolysis is unusual in that is uses inorganic phosphate as a reactant rather than phosphate/phosphoryl attached to another molecule?
Production of fructose 1,6-bisphosphate
Production of Glucose 6-phosphate
Production of Pyruvate
Production of 1,3-bisphosphoglycerate
Production of 3-phosphoglycerate
Production of 1,3-bisphosphoglycerate
Which is NOT a function of reactions of the Pentose Phosphate Pathway in the cell?
Facilitate photosynthesis
Conversion of a six-carbon sugar to a three-carbon sugar to produce ATP and NADH
Facilitates the reductive synthesis of fatty acids.
Helps counter oxidative damage during the transport of O2
Helps produce the sugars used to build DNA and RNA
Conversion of a six-carbon sugar to a three-carbon sugar to produce ATP and NADH
In animals, an enzyme UNIQUE to gluconeogenesis is:
Fructose-1,6 bisphosphatase
Glyceraldehyde 3-phosphate dehydrogenase
Enolase
Phosphoglyceromutase
Aldolase
Fructose-1,6 bisphosphatase
An enzyme used NEITHER in glycolysis NOR in gluconeogenesis is:
glucose 6-phosphatase.
pyruvate kinase.
phosphoglycerate kinase.
Phosphoglucomutase
hexokinase.
Phosphoglucomutase
It is critical to regenerate reaction intermediates in metabolic pathways for them to continue. In anaerobic conditions, what is the product when pyruvate is reduced to regenerate NAD+ in one form of fermentation?
Lactate
Glycogen
Glucose
ATP
NADH
Lactate
When lactic acid accumulates in muscles it is gradually carried away by the blood to the liver. What effect does lactic acid have on the respiratory rate?
It decreases the respiratory rate
Respiratory rate will initially decrease and the rapidly level off
It has no effect on the respiratory rate
It increases the respiratory rate
It increases the respiratory rate
Based on the last reaction of glycolysis, what can be said about the hydrolysis of PEP versus ATP
Hydrolysis of ATP is more spontaneous than hydrolysis of PEP
The rate of PEP hydrolysis is greater than the rate of ATP hydrolysis
The rate of ATP hydrolysis is greater than the rate of PEP hydrolysis
Free energy of hydrolysis is equal for PEP and ATP
Hydrolysis of PEP is more spontaneous than hydrolysis of ATP
Hydrolysis of PEP is more spontaneous than hydrolysis of ATP
The 1st and 3rd reactions of glycolysis are phosphoryl group transfers from ATP. What ion is also required for this reaction?
Mg2+
PO4 3-
Mn2+
H+
Ca2+
Mg2+
How is wasteful hydrolysis of a high-energy bond by hexokinase prevented?
Glucose doesn’t bind enzyme if enzyme is not already bound to ATP
Glucose doesn’t bind the enzyme during normal catalysis
ATP doesn’t bind enzyme if enzyme is not already bound to glucose
ATP doesn’t bind the enzyme during normal catalysis
Water cannot enter the active site of hexokinase
ATP doesn’t bind enzyme if enzyme is not already bound to glucose
How many net NADH molecules are produced from one glucose molecule in glycolysis?
2
None, no net NADH is made
8
4
1
2
Which of the following is a metabolic response to low blood glucose levels?
increased levels of insulin in blood
Increased Glucagon levels
Increased glycogen synthesis
Increased glycolysis
Decreased glycogen phosphorylase activity
Increased Glucagon levels
Under anaerobic conditions mammals utilize a process termed the “Cori Cycle” in which glucose is fermented to lactic acid in the muscle, and lactic acid is transported to the liver where it is converted back to glucose. During these processes, the net gain/loss of other metabolites is:
+2 ATP in muscle, -6 ATP in liver
+32 ATP in muscle
+2 ATP and +1 NADH in muscle, -6 ATP in liver and -1 NADH in liver
+2 ATP in muscle, -4 ATP in liver
+2 ATP and +1 NADH in muscle, -4 ATP in liver and -1 NADH in liver
+2 ATP in muscle, -6 ATP in liver
Which of the following molecules is a potent regulator of both Glycolysis and Gluconeogenesis?
NAD+
Glucose
Fructose 1,6-bisphosphate
Pyruvate
Fructose 2,6-bisphosphate
Fructose 2,6-bisphosphate
What is FALSE given what we know about the thermodynamics of the Fructose 1,6 bisPhosphatase reaction?
It is an irreversible step that doesn’t need coupling to another highly irreversible step
ATP has a higher phosphoryl group transfer potential than fructose 1,6 bisP
It is an example of a hydrolysis reaction
Pi is a product of the reaction
ATP has a lower phosphoryl group transfer potential than fructose 1,6 bisP
ATP has a lower phosphoryl group transfer potential than fructose 1,6 bisP
Which of the following enzymes is not bypassed in gluconeogenesis?
Enolase
Hexokinase
Pyruvate Kinase
Phosphofructokinase 1
Enolase
What general reaction type catalyzes the transfers a functional group from one position to another position on the same molecule?
Aldolases
Enolases
Dehydrogenases
Catalases
Mutases
Mutases
What enzyme catalyzes glycogen breakdown to glucose?
Glycogen phosphorylase
Glycogen phosphatase
Transglycolase
Glucose phosphatase
Glycogen kinase
Glycogen phosphorylase
Conversion of pyruvate to phosphoenolpyruvate requires an important cofactor that will come up often in the rest of the course. Which one of the following is that cofactor, a carrier of CO2?
Pyrophosphate (PPi)
Niacin
Magnesium
Biotin
Thiamine
Biotin
Which of the following is TRUE about aerobic glycolysis?
There is a net production of one NAD+ in this pathway
There is a net oxidation of glucose
It is the pathway used by yeast to produce ethanol
The carbons in pyruvate and glucose are in the same oxidation state
Pyruvate is readily converted to lactate which accumulates in the muscles
There is a net oxidation of glucose
The first reaction in glycolysis that results in the FORMATION of a compound with high phosphoryl transfer potential is catalyzed by:
pyruvate kinase
Glyceraldehyde 3-phosphate dehydrogenase (GAPDH)
phosphofructokinase-1.
phosphoglycerate kinase
Hexokinase
Glyceraldehyde 3-phosphate dehydrogenase (GAPDH)
The principle behind using PET scans (with a radiolabeled glucose analog) to diagnose cancer metastasis is the:
none of the other answers are correct
greater uptake of glucose by cancer cells than normal cells
greater increase in glycolytic enzymes in cancer cells than normal cells
formation of lactic acid in cancers due to hypoxic conditions
difference in tissue-density of the tumor and the surrounding normal tissue
greater uptake of glucose by cancer cells than normal cells
Gluconeogenesis requires the conversion of pyruvate (or lactate) to phosphoenolpyruvate in a bypass reaction. In which two cellular locations CAN this conversion take place (bearing in mind there are 2 alternative paths)?
Rough endoplasmic reticulum and cytosol
Golgi and rough endoplasmic reticulum
Plasma membrane and cytosol
Mitochondria and cytosol
Cytosol and Golgi
Mitochondria and cytosol
What products do you expect from a mixture of a 6-carbon and a 4-carbon-containing sugar-phosphate substrate in the presence of a transaldolase enzyme?
8 and 2 carbon containing sugar phosphate
Only one 10 carbon containing sugar phosphate
5 and 5 carbon containing sugar phosphate
7 and 3 carbon containing sugar phosphates
9 and 1 carbon containing sugar phosphates
7 and 3 carbon containing sugar phosphates
An enzyme that uses two PENTOSES as substrates to produce a HEPTOSE and a TRIOSE is a
Aldolase
Triose phosphate isomerase
Transaldolase
Transketolase
Kinase
Transketolase
Identify an important enzymes that function in anaerobic fermentation in yeast.
Glucose 6-phosphatase
Pyruvate decarboxylase
Alcohol carboxylase
Coenzyme A
Lactate dehydrogenase
Pyruvate decarboxylase
The oxaloacetate-to-malate-to-oxaloacetate chain of reactions of gluconeogenesis is important because
this is the only way lactate can be used to synthesize glucose.
It couples with a highly irreversible step to make the overall pathway irreversible
this chain-of-reactions is the only way in which gluconeogenesis can occur
It allows the apparent transfer of NADH from the mitochondria to cytosol
It allows stimulation of glycolysis and gluconeogenesis at the same time.
It allows the apparent transfer of NADH from the mitochondria to cytosol
How many of the intermediates of glycolysis is/are phosphorylated?
All of them
2
9
4
5
9
Which statement is FALSE regarding the reciprocal regulation of glycolysis and gluconeogenesis?
The regulation of the committed step of glycolysis is a major part of reciprocal regulation
Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1
The enzyme responsible for synthesizing a regulator of reciprocal regulation contains not only the activity to make the regulator but also the activity to consume/degrade the regulator
The cell doesn’t want to simultaneously activate both glycolysis and gluconeogenesis
AMP can regulate both glycolysis and gluconeogenesis
Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1
In which organisms does GLYCOLYSIS occur?
Only in heterotrophs and not in autotrophs
Aerobic organisms only
Anaerobic organisms only
Only in autotrophs and not in heterotrophs
Both aerobic and anaerobic organisms
Both aerobic and anaerobic organisms
What product of ethanol fermentation is also an important reactant in Glycolysis?
NAD+
Inorganic phosphate
Glucose
ATP
Glyceraldehyde 3-phosphate
NAD+
What is false about the Pentose Phosphate Pathway?
It is an irreversible pathway
It generates important cellular precursors
It is employed in rapidly dividing cells
It has two phases, an oxidative phase and a reductive phase
It is important for helping maintain the redox status of the cellular environmen
It has two phases, an oxidative phase and a reductive phase
What is one of the two products formed during Pyruvate fermentation by yeast?
Acetyl-CoA
Glucose
Carbon dioxide
NADH
Lactate
Carbon dioxide
An enzyme involved in glycogen breakdown is
glycogen phosphorylase.
transketolase
glycogen synthase.
Glycogenin
branching enzyme
glycogen phosphorylase.
Which one of these will NOT help in making the free energy change for a cellular process become more negative?
Accumulation of reactant
A decrease in the mass action ratio
Depletion of product
Accumulation of product
Accumulation of product
How many electrons and protons are transferred to NAD+ during a Dehydrogenation reaction in Biochemical pathways?
1 e- and 1 H+
2 e- and 2 H+
1 e- and 2 H+
4 e- and 4H+
2 e- and 1 H+
2 e- and 1 H+
Which of the following is a good indicator of large changes in the net rate of a metabolic pathway caused by small changes in specific substrate and product concentrations of a specific reaction of that pathway?
Compare ΔG’o for the steady state and the accelerated or inhibited reactions
Compare Vmax of the steady state to the Vmax for the accelerated or inhibited reactions
Compare the Vo for the steady state to the Vo for the accelerated or inhibited reactions
Compare the Turnover number to the Catalytic Efficiencies
Compare the Mass Action Ratio to K’eq for the reaction
Compare the Mass Action Ratio to K’eq for the reaction
Which molecule has the highest oxidation state?
Carbon dioxide (CO2)
Formaldehyde (CH2O)
Carbon monoxide (CO)
Methane (CH4)
Acetaldehyde (CH3COH)
Carbon dioxide (CO2)
Which of the following is NOT one of the 3 possible catabolic fates of Pyruvate that is formed in Glycolysis, as directly described in our text and others.
Fermentation to lactate
Complete oxidation to carbon dioxide and water through the Kreb’s Cycle
Oxidation to ribose 5-phosphate in the Pentose Phosphate Pathway
Fermentation to ethanol
Oxidation to ribose 5-phosphate in the Pentose Phosphate Pathway
Which of the following is not one of the three important groups that are donated by (transferred from) ATP under nucleophilic attack in metabolic reactions?
Cyclic monophosphoryl
Adenylyl
Phosphoryl
Pyrophosphoryl
Cyclic monophosphoryl
Select the TRUE statement
In a redox reaction, there is a transfer of electrons from one molecule/ion to another.
Reduction of a compound involves removal of electrons from it.
Dehydrogenase enzymes remove both two e- and two hydride ions from the same molecule.
In fermentation, pyruvate is oxidized to lactate.
Oxidation of a compound involves addition of electrons to it.
In a redox reaction, there is a transfer of electrons from one molecule/ion to another.
Phosphofructokinase is tightly regulated in glycolysis by allosteric modulators. Which of the following is NOT an allosteric modulator of PFK-1?
AMP
Fructose 2,6-bisphosphate
ATP
Glucose
ADP
Glucose
Which of the following is NOT one of the important metabolic “Fates” of pyruvate that is formed by glycolysis?
CO2
Lactate
Ethanol
NADH
Dihydroxyacetaone phosphate
Dihydroxyacetaone phosphate
Which statement is FALSE regarding the reciprocal regulation of glycolysis and gluconeogenesis?
The enzyme responsible for synthesizing a regulator of reciprocal regulation contains not only the activity to make the regulator but also the activity to consume/degrade the regulator
The regulation of the committed step of glycolysis is a major part of reciprocal regulation
The cell doesn’t want to simultaneously activate both glycolysis and gluconeogenesis
Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1
AMP can regulate both glycolysis and gluconeogenesis
Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1
It is uncommon for one molecule to act as both an activator and inhibitor in metabolism. Which of the following molecules both activates glycolysis and inhibits gluconeogenesis?
Glucose 6-phosphate
Pyruvate
Fructose 2,6-bisphosphate
NAD+
ADP
Fructose 2,6-bisphosphate
Which of the following is a feedback inhibitor of phosphofructokinase-1?
ATP
Glyceraldehyde-3-phosphate
Pyruvate
NADH
3-phosphoglycerat
ATP
Under which scenario will the rate of gluconeogenesis in the liver be much GREATER than that of glycolysis?
Low pyruvate concentration in muscle cells
increased blood sugar
Low ATP/AMP ratio in the muscle cells
High level of AMP in muscle cells
Starvation
Starvation
Which statement about free glucose storage is FALSE?
If all glucose were available as free glucose (not glycogen) the concentration gradient of intra- and extracellular glucose would be prohibitively large.
The free energy difference between intra- and extracellular free glucose would be difficult to overcome for glucose uptake by the cell.
Glucose is insoluble and cannot contribute to the osmotic balance of the cell.
All statements are true
Glucose is insoluble and cannot contribute to the osmotic balance of the cell.
When K’eq is ________ delta G’o is _______.
Greater than 1, negative
Less than 1, negative
0, Positive
0, negative
Greater than 1, positive
Greater than 1, negative
Sucrose and mannose both can enter Glycolysis through Feeder Pathways at what intermediate?
Glucose 6-phosphate
3-phosphoglycerate
Fructose 1,6-bisphosphate
Glucose 1-phosphate
Fructose 6-phosphate
Fructose 6-phosphate
Under low levels of glucose in the blood, the liver decreases its glycolytic rate and instead elevates the rate of
aerobic respiration
gluconeogenesis
glycogen synthesis
inhibition of glycogen phosphorylase
anaerobic respiration
gluconeogenesis
Which one would be an example of a highly spontaneous reaction?
Change in free energy is 0 kJ/mol
Change in free energy is -2 kJ/mol
Change in free energy is +20 kJ/mol
Change in free energy is -20 kJ/mol
Change in free energy is +2 kJ/mol
Change in free energy is -20 kJ/mol
What is a chemical rationale for the release of a CO2 molecule during the oxidative phase of the Pentose Phosphate Pathway?
Reduction of pyruvate to ethanol results in release of CO2
Reduction of pyruvate to acetaldehyde results in release of CO2
Oxidation of CO by atmospheric oxygen produces CO2
Lipids and ribose 5-phosphates are reduced so that glucose can be oxidized to CO2
Beta keto acids formed upon oxidation decarboxylate spontaneously
Beta keto acids formed upon oxidation decarboxylate spontaneously
What part of UTP is transferred to glucose 1P to form glucose-UDP for glycogen synthesis?
Phosphoryl group
UTP
Uracil
Uridylyl (UMP) group
UDP
Uridylyl (UMP) group
The enzyme that catalyzes the branching of glycogen polymers catalyzes
Breakage of (α1 → 6) bonds
Synthesis of (α1 → 6) bonds
Synthesis of (α1 → 4) bonds
Synthesis of (beta1 → 4) bonds
Breakage of (beta1 → 4) bonds
Synthesis of (α1 → 6) bonds
Which cofactor, or more properly prosthetic group, can perform as a one-electron or a two-electron carrier?
NADPH
Coenzyme A
Magnesium
FAD
NADH
FAD
Which one is not a defining feature of a committed step of a pathway?
It is the only irreversible reaction in the pathway
The reaction has a free energy change in the cell that is negative
It is a highly regulated step in the pathway
It must be a spontaneous reaction under the conditions of the cell
Most feed-in metabolites enter the pathway before this step
It is the only irreversible reaction in the pathway
The change in free energy (ΔG’o) for the above reaction is -16.7 kJ/mol. The reaction that comes next in glycolysis has a free energy change of 1.7 kJ/mol. The pH of these reactions is optimal near 7.4. What is the overall free energy change for these reactions?
-15 kJ/mol.
-18.4 kJ/mol
15 kJ/mol
-28.4 kJ/mol
18.4 kJ/mol
-15 kJ/mol.
Glucose residues are removed from glycogen until a branch in the polysaccharide is reached. What specifically happens at the branch to permit more catabolism?
More glucose residues are removed at branches by the same glycosidases that remove non-branched glucose since the enzyme is multifunctional
Nothing happens since we cannot break any branches
“Debranching Enzyme” breaks the branches
The alpha-1,6-glycosidic linkage is converted to a beta-1,6-glycosidic linkage, and then a glycosidase cleaves it
“Debranching Enzyme” breaks the branches
Glycolysis produces important products for other cells than the ones making it. What is the net production of ATP and NADH from one Glucose molecule?
1, 1
1, 2
4, 2
2, 4
2,2
2,2
For the reaction A to B, DeltaG’° = –60 kJ/mol. The reaction is started with 10 mmol of A; no B is initially present. After 24 hours, analysis reveals the presence of 2 mmol of B, 8 mmol of A. Which is the most likely explanation?
A and B have reached equilibrium concentrations.
An enzyme has shifted the equilibrium toward A.
Formation of B is thermodynamically unfavorable.
B formation is kinetically slow; equilibrium has not been reached by 24 hours.
The result described is impossible, given the fact that DeltaG’° is –60 kJ/mol.
B formation is kinetically slow; equilibrium has not been reached by 24 hours.
Glycogen synthase CANNOT
Add glucose to the reducing end of a glycogen polymer
form (alpha 1->4) linkages in a growing glycogen polymer
Get phosphorylated in the cell, ever.
Use a large growing glycogen polymer as a reactant
Use Glucose-UDP as a building block to grow a glycogen polymer
Add glucose to the reducing end of a glycogen polymer
Pyruvate kinase transfers a phosphate group from phosphoenolpyruvate (PEP) to ADP, forming pyruvate and ATP. This reaction is essentially irreversible. Which of the following is the best explanation for the irreversible nature of this reaction?
The change in free energy for the overall reaction is large and negative
There is a different enzyme in the cell that synthesizes PEP
Binding of pyruvate to the active site is weak relative to binding of PEP
Reaction is coupled to pyruvate dehydrogenase reaction
Hydrolysis of ATP is highly favorable
The change in free energy for the overall reaction is large and negative
If the standard change in free energy of the reaction is +73 kJoule/mole, what is true about this reaction at standard conditions?
will occur at a very fast pace.
will occur at a very slow pace.
will occur spontaneously.
will not occur spontaneously.
More information is needed to determine if the reaction will be spontaneous or not under these conditions.
will not occur spontaneously.
Which statement is true about biochemical oxidation-reduction reactions?
Dehydrogenases typically remove two electrons and two hydrides.
Every oxidation must be accompanied by a reduction.
During oxidation a compound gains electrons.
They usually proceed through homolytic cleavage.
There are two commonly accessed oxidation states of carbon.
Every oxidation must be accompanied by a reduction.
If the cell needs to replenish nucleoside triphosphates for suddenly increasing transcription, it will probably
increase only the steps that increase NADPH production to reduce ribose to deoxyribose
increase only the oxidative phase of the PPP
increase the flux through the complete PPP cyclic pathway
increase only the non-oxidative phase of the PPP
increase only the oxidative phase of the PPP
When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which statement is MOST nearly correct, when applied to the reaction shown (R = 8.315 J/mol · K and T = 298 K)?
glucose 6-phosphate ⇋ fructose 6-phosphate
ΔG’°is incalculably large and positive.
ΔG’°is zero.
ΔG’° is –1.7 kJ/mol.
ΔG’° is +1.7 kJ/mol.
ΔG’°is incalculably large and negative.
ΔG’° is +1.7 kJ/mol.
What enzyme will be activated by the AMP, which then activates other ATP-producing pathways?
Pyruvate kinase
Phosphofructokinase-1
Hexokinase IV
cAMP-dependent protein kinase
AMP-dependent protein kinase
AMP-dependent protein kinase
Which of the following is also a high-energy bond that carries a lot of potential energy, making it relatively common in metabolism.
Biphosphate of NADH
Coenzyme A
Bisphosphates on phosphoinositides
Thioester
3’5’-phosphate linkage of cAMP
Thioester
Which of the following is a metabolic response to high blood glucose levels?
Increased glycogen phosphorylase activity
Decreased glycolysis
Increased levels of insulin in blood
Decreased glycogen synthesis
Increased Glucagon levels
Increased levels of insulin in blood
For the reaction, ΔG’° = +29.7 kJ/mol
L-malate + NAD+ → oxaloacetate + NADH + H+
The reaction as written:
may occur in cells at some concentrations of substrate and product.
can occur only in a cell in which NADH is converted to NAD+ by electron transport.
can never occur in a cell.
can occur in a cell only if it is directly coupled to another reaction for which ΔG’° is negative.
cannot occur because of its large activation energy.
may occur in cells at some concentrations of substrate and product.
What term best characterizes the following: ADP + GTP → ATP + GDP
Phosphorylation
Adenylylation
Prenylation
Autophosphorylation
Transphosphorylation
Transphosphorylation
What enzyme then removes glucose from glycogen in a phosphorolysis reaction?
Glycogen kinase
Inorganic pyrophosphatase
Glycogen phosphorylase
Glycogenin
Glycogen synthase
Glycogen phosphorylase
What important reaction occurred to yield α-ketoglutarate from isocitrate
Substrate level phosphorylation and hydration
Decarboxylation and reduction of NAD+
Decarboxylation and hydration
Decarboxylation and oxidation of NADH
Decarboxylation and reduction of NAD+
What Product of the Glyoxylate Cycle is a Reactant of the Citric Acid Cycle?
Aspartate
Succinate
Alpha-ketoglutarate
Aconitate
Glyoxylate
Succinate
The conversion of 1 mol of glucose to 6 mol of CO2 via glycolysis and the citric acid cycle also yields _____ mol of NADH, _____ mol of FADH2, and _____ mol of ATP/GTP (total).
5, 1, 2
3, 1, 1
0, 0, 32
4, 1, 1
10; 2; 4
10; 2; 4
Which of the following molecules is NOT associated with Ketone Bodies?
Acetoacetate
Beta-hydroxybutyrate
Acetyl-CoA
Acetone
Acetyl-CoA
Acyl-CoA dehydrogenase passes electrons to the Electron Transferring Flavoprotein (ETF). What molecule is the immediate source of these electrons? That is, what molecule in ETF and acts as the last electron donor before the electron transport chain?
NADH
Fatty acyl-CoA
Acetyl CoA
FAD
Malonyl-CoA
FAD
What enzyme catalyzes an isomerization reaction in the Citric Acid Cycle?
triose phosphate isomerase
citrate synthase
phosphoglycerate mutase
Succinyl CoA synthetase
Aconitase
Aconitase
Full oxidation of a polyunsaturated fatty acid (18:2) gives rise to a product NOT given out by full oxidation of a monounsaturated fatty acid (18:1). This product is most likely:
water
NADP+
NADH
Acetyl-CoA
FADH2
NADP+
What reaction uses Pi as a substrate? Reaction catalyzed by:
Glucose 6P dehydrogenase
Citrate synthase
Phosphofructokinase-1
Glyceraldehyde 3-phosphate dehydrogenase
Pyruvate carboxylase
Glyceraldehyde 3-phosphate dehydrogenase
What two chemical mechanisms change pyruvate to acetyl-CoA in the pyruvate dehydrogenase complex?
Condensation and oxidation
Dehydrogenation and decarboxylation
Dehydrogenation and oxidation
Decarboxylation and condensation
Condensation and dehydrogenation
Dehydrogenation and decarboxylation
Triglycerides and lipoproteins associate into what structure which is a vascular carrier of these lipids?
Glyoxysomes
Mitochondria
Bile salts
Chylomicrons
Peroxisomes
Chylomicrons
Of the reactions that produce alpha-ketoglutarate and succinyl-CoA, both use what reaction mechanism?
Phosphorylation
Oxidative decarboxylation
Hydration
Dehydration
Dehydrogenation
Oxidative decarboxylation
Which of the following does not serve as a coenzymes or prosthetic group for the Pyruvate Dehydrogenase Complex?
Coenzyme A
Lipoate
Thiamine pyrophosphate
Flavin adenine nucleotide
Biotin
Biotin
The conversion of 1 mol of pyruvate to 3 mol of CO2 via pyruvate dehydrogenase and the citric acid cycle also yields _____ mol of NADH, _____ mol of FADH2, and _____ mol of ATP/GTP (total).
4; 1; 1
2; 2; 2
3; 2; 0
4; 2; 1
3; 1; 1
4; 1; 1
Acyl chains with odd numbers of carbons can undergo oxidation, yielding which of the following as a final product molecule?
β-hydroxybutyrate
Propionyl-CoA
Acetyl CoA
Palmitate
Acetone
Propionyl-CoA
Which of the following is not a component of Chylomicrons?
Phospholipids
Apolipoproteins
Triacylglycerols
Cholesterol
Bile Salts
Bile Salts
Which one is used to partly digest ingested fats in the adipose tissues in response to low blood sugar?
Intestinal lipase
Hormone sensitive lipase
Lipoprotein lipase
HGM-CoA lyase
All the answers can perform this function
Hormone-sensitive lipase
What combination of step and enzyme accurately depict a reaction in fatty acyl-CoA beta oxidation that uses a prosthetic group for catalyzing a redox reaction?
Step 1 – beta-hydroxyacyl-CoA dehydrogenase
Step 3 – beta-hydroxyacyl-CoA dehydrogenase
Step 1 – acyl-CoA dehydrogenase
Step 3 - acyl-CoA dehydrogenase
None of the combinations are correct
Step 1 – acyl-CoA dehydrogenase
What is the direct role of NAD+ in the pyruvate dehydrogenase complex reaction cascade?
It oxidizes FADH2
It reduces FADH2
It reduces lipoate
It reduces TPP
It oxidizes TPP
It oxidizes FADH2
Pools of which of the following enzyme(s) are found in both the mitochondrial matrix and the cytosol:
Succinate dehydrogenase
All of these
None of these
Lactate dehydrogenase
Malate dehydrogenase
Malate dehydrogenase
Aconitase has an unusual chemical feature associated with 3 Cys residues. What is that feature?
Binding site for a competitive inhibitor
Iron-sulfur center
Disulfide linkage
Heme group
Cytochrome
Iron-sulfur center
What is the common feature of these three reactions: isocitrate dehydrogenase, pyruvate dehydrogenase complex, and alpha-ketoglutarate dehydrogenase complex?
All three are highly endergonic
All three require prosthetic groups
All three produce CoA-SH
All three require NADH
All three produce CO2
All three produce CO2
Which of the following enzymes is not involved in a decarboxylation reaction?
All of the above are involved in decarboxylation reactions
Isocitrate dehydrogenase
Alpha-ketoglutarate dehydrogenase
Pyruvate dehydrogenase
Malate dehydrogenase
Malate dehydrogenase
What class of lipids is the primary target of beta-oxidation?
Triglycerides
Phospholipids
Sphingolipids
Glycerols
Glycerophospholipids
Triglycerides
Which one of these fatty acids when oxidized would give rise to propionyl-CoA as a product?
(18:3)
(16:2)
(20:1)
(22:0)
(17:0)
(17:0)
High cellular concentrations of what molecule would INHIBIT the entry of pyruvate via acetyl CoA into the citric acid cycle?
NADH
AMP
Calcium (Ca2+)
Coenzyme A
oxaloacetate
NADH
Which of the following pathways produces Succinyl-CoA for the Kreb’s Cycle?
Oxidation of polyunsaturated fatty acids
Beta-oxidation of fatty acids with even numbers of carbons
Oxidation of phospholipids
Beta-oxidation of fatty acids with odd numbers of carbons
Oxidation of monounsaturated fatty acids
Beta-oxidation of fatty acids with odd numbers of carbons
When a fatty acid of chemical formula 22:1 Δ9 is oxidized using the beta-oxidation pathway, the number of FADH2 produced will be:
9
8
11
22
10
9
How is a specific reaction in the Citric Acid Cycle that uses an achiral substrate able to form only one enantiomeric form of a chiral product?
The energy of ATP hydrolysis drives chiral center formation.
Only one enantiomer of the substrate can fit in the active site
All enzymes, their active sites, and their complexes with the transition state of a reaction are chiral.
Substrate-level phosphorylation.
Water can be chiral at 55.5 M concentration
All enzymes, their active sites, and their complexes with the transition state of a reaction are chiral.
A coenzyme/cosubstrate required for formation of an acyl-CoA and an acetyl-CoA from beta-ketoacyl-CoA during beta oxidation
CoA-SH
NAD+
FAD
All other answers are correct.
H2O
CoA-SH
What additional reactant is required for oxidation of polyunsaturated fatty acids compared with saturated fatty acids?
NAD+
ATP
FAD
NAD(P)H
Acetyl-CoA
NAD(P)H
Which one of the following enzymatic activities would be decreased by the decreased uptake of thiamine by chronic alcohol users?
alpha-Ketoglutarate dehydrogenase complex
Malate dehydrogenase
Isocitrate dehydrogenase
Succinate dehydrogenase
Fumarase
alpha-Ketoglutarate dehydrogenase complex
If the FREE FATTY ACID (16:1) is catabolized completely, to carbon dioxide and water, the NET yield of ATP (i.e., ATP potential from NTP, NADH, and FADH2) per molecule of FREE FATTY ACID is _____ ATP.
108
106.5
106
104.5
112
104.5
What the two additional reaction mechanisms are performed on the unsaturated fatty acid, Linoleic acid (18:3) in the correct order, to permit its entry into beta-oxidation?
Isomerization, Reduction
Oxidation, reduction
Reduction, Isomerization
Oxidation, hydration
Isomerization, Oxidation
Isomerization, Reduction
What class of proteins is associated with chylomicrons and functions to target lipids for delivery to specific tissues?
Apolipoproteins
Carnitines
Perilipins
Serum albumin
Phospholipases
Apolipoproteins
Which of the following important reactants is NOT produced by the first 5 steps of the Kreb’s Cycle?
Succinate
All of the above are produced by the first 5 steps
CO2
GTP
NADH
All of the above are produced by the first 5 steps
Malonate is a competitive inhibitor of succinate dehydrogenase. If malonate is added to a mitochondrial preparation that is oxidizing pyruvate as a substrate, which of the following compounds would you expect to immediately decrease in concentration?
Isocitrate
Succinate
Pyruvate
Citrate
Fumarate
Fumarate
How many acetyl-CoA molecules are obtained from linoleic acid [18:2 (Δ 9,12)] via beta-oxidation?
7
The number cannot be determined with the given information
18
9
16
9
Where does ketogenesis occur in primates such as humans?
adipose tissue
skeletal muscle
the brain
the liver
both the liver and adipose tissue
the liver
Which one of the following is not occurring in the Citric Acid Cycle?
Substrate-level phosphorylation
FADH2 formation
Oxidative decarboxylation
C-C bond formation reaction
Acetyl CoA formation
Acetyl CoA formation
What valuable Citric Acid Cycle intermediate is made by PEP carboxykinase and by PEP carboxylase, a molecule that is usually in low concentration in cells?
Oxaloacetate
Fumarate
Pyruvate
Citrate
Malate
Oxaloacetate
Which one of the following is not part of the Citric acid cycle?
Oxidation of pyruvate
Formation of a C-C bond
Synthesis of NTP
Use of FAD+ as a substrate
Simultaneous oxidation and loss of CO2
Oxidation of pyruvate
What molecule serves as an example of how an intermediate on one energy-generating metabolic pathway can regulate the flux through ANOTHER energy-generating metabolic pathway?
Mg2+
Fructose 1,6 bisP
ATP
Citrate
O2
Citrate
The reaction in the beta-oxidation of fatty acids that is most similar to the reaction catalyzed by fumarase in the citric acid cycle is catalyzed by:
acyl CoA dehydrogenase
enoyl CoA hydratase
thiolase
hormone-sensitive lipase (HSL)
beta-hydroxy acyl CoA dehydrogenase
enoyl CoA hydratase
Which of the following intermediates can be used to produce Phosphoenolpyruvate that could be used in Gluconeogenesis?
Malate
Succinyl CoA
Pyruvate
Succinate
Oxaloacetate
Oxaloacetate
-oxidation comprises a repeating set of 4 reactions that remove acetyl groups from acyl chains. Which reaction involves a thiolate in a cleavage reaction?
None of the steps involve a thiolate group
Step 1
Step 2
Step 3
Step 4
Step 4
A coenzyme/cosubstrate required for formation of a beta-ketoacyl-CoA from a beta-hydroxyacyl-CoA is
FAD
NAD+
CoA-SH
All other answers are correct.
TPP
NAD+
GTP is produced by the Kreb’s Cycle. What important enzyme can then produce ATP from the GTP if there is sufficient ADP present?
Nucleoside diphosphate kinase
Protein kinase A
F-type ATPase
Adenylate kinase
Adenylate cyclase
Nucleoside diphosphate kinase
Triacyl glycerol stores energy not only in the form of fatty acids but also in the form of a product that can be metabolized to undergo
Entire PPP cycle
Oxidative phase of the PPP
The ATP-generating steps of glycolysis
Non-oxidative phase of the PPP
None of the answers is correct
The ATP-generating steps of glycolysis
Plants can make glucose out of fatty acids because
They encode odd-numbered fatty acids that are not found in animals
They are able combine the glyoxylate cycle to the CAC in the mitochondria
The rate of fatty acid oxidation is greater in plants that in animals
The oxaloacetate concentrations are much higher in plants
None of the other answers is true.
They are able combine the glyoxylate cycle to the CAC in the mitochondria
What is the location for ketone body biogenesis?
Hepatocytes
Glial cells
Adipocytes
Myocytes
Neurons
Hepatocytes
How many ATP equivalents are required to produce an activated fatty acid in order for it to enter beta-oxidation?
1
None, because GTP is the source of energy
3
One for beta-oxidation and two for omega-oxidation
2
2
The redox reaction catalyzed by which of these enzymes uses a cofactor/co-enzyme/prosthetic group that is different than that of all the other ones? (In other words, all the other enzymes use the same redox cofactor/co-enzyme/prosthetic group)
glucose 6-phosphate dehydrogenase
malate dehydrogenase
succinate dehydrogenase
isocitrate dehydrogenase
glyceraldehyde 3-phosphate dehydrogenase
succinate dehydrogenase
Which of the following statements is TRUE regarding the thermodynamics of the Citric Acid Cycle?
The Cycle is an endergonic set of reactions
The free energy input is significantly positive, but the equilibrium indicates that the Cycle will continue uninterrupted
All the reactions contain free energy changes that are near 0, which is one reason why the cycle can continue uninterrupted
It is an exergonic set of reactions
Only the final 3 steps are significantly negative, but the sum of these three free energy changes drive the rest of the Cycle
It is an exergonic set of reactions
Which of the following would contain Glyoxysomes?
Algae
Gram-negative bacteria
Vertebrates
Yeast
Leafy plants
Leafy plants
Chylomicrons are associated with lipid metabolism. What is their function?
Oxidation of fatty acyl chains in plants and algae
Oxidation of fatty acyl-CoA that have odd numbers of carbons
Transport of triglycerides in the blood
Assembly of acyl chains and glycerol into triacylglycerols
Transport of fatty acyl chains from the gut lumen to the vascular space
Transport of triglycerides in the blood
Malonate is a competitive inhibitor of succinate dehydrogenase. If malonate is added to a mitochondrial preparation that is oxidizing pyruvate as a substrate, which of the following compounds would you expect to immediately decrease in concentration?
Citrate
Pyruvate
Isocitrate
Succinate
Fumarate
Fumarate
A substrate required for formation of a beta-hydroxyacyl-CoA from trans-Δ2-enoyl-CoA is
FAD
H2O
CoA-SH
All other answers are correct.
NAD+
H2O
Which reaction of the Citric Acid Cycle combines a 4-carbon and a 2-carbon intermediate to form a 6-carbon intermediate?
2
3
5
1
4
1
Citric Acid Cycle happens in the _____ and glycolysis happens in the _____.
Plasma membrane, Cytosol
Mitochondria, Cytosol
Cytosol, Cytosol
Cytosol, Mitochondria
Cytosol, Plasma membrane
Mitochondria, Cytosol
Plants contain a lot of fatty acids with odd numbers of carbons. Oxidation of these lipids produces Propionyl-CoA.
Complete oxidation of this molecule requires extra reactions that produce what Krebs Cycle intermediate as the final product?
Malate
Citrate
Succinate
Succinyl-CoA
Alpha-ketoglutarate
Succinyl-CoA
All redox reactions of the citric acid cycle are linked to the reduction of nicotinamide-containing molecule EXCEPT that catalyzed by:
succinate dehydrogenase.
α-ketoglutarate dehydrogenase complex
malate dehydrogenase.
pyruvate dehydrogenase
isocitrate dehydrogenase.
succinate dehydrogenase.
The three-carbon product from the hydrolysis of triacylglycerols is fed into glycolysis as:
dihydroxyacetone-1,3- bisphosphate.
Glyceraldehyde 3-phosphate
acetyl CoA.
glucose-6-phosphate.
glucose.
Glyceraldehyde 3-phosphate
The isomerization of citrate to isocitrate:
protects cells from the toxic effects of arsenite ion.
is an oxidation reaction.
converts a tertiary alcohol, which cannot easily be oxidized, to a secondary alcohol that can be oxidized.
is a major regulatory step for the citric acid cycle.
is the only unnecessary step of the citric acid cycle.
converts a tertiary alcohol, which cannot easily be oxidized, to a secondary alcohol that can be oxidized.
The fatty acid molecules obtained in a blood draw from a healthy individual will be found to be
Bound to a protein belonging to the albumin family.
Water-soluble as they are much smaller and more hydrophilic than triacylglycerol
Bound to bile salt micelles.
Bound to carnitine.
Bound to myoglobin.
Bound to a protein belonging to the albumin family.
How many molecules of acetyl CoA are produced from a single molecule of glucose for participation in the Krebs cycle?
4
2
1
0
3
2
A combination of a cyclic pathway in the glyoxysome/peroxisome and a cyclic pathway in the mitochondria is used
For the synthesis of fatty acids from acetyl-CoA in animals.
To perform oxidative phosphorylation
for gluconeogenesis in a hibernating bear
For gluconeogenesis starting with fatty acids
For the synthesis of fatty acids from TCA cycle intermediates.
For gluconeogenesis starting with fatty acids
One reason that fatty acids make an excellent source of fuel is that they carry more energy per carbon atom than do carbohydrates. This is because:
The carbons in fatty acids are more hydrophobic than the carbons in carbohydrates.
The carbons in fatty acids are lighter than carbons in carbohydrates.
The carbons in fatty acids are more polar than the carbons in carbohydrates.
The carbons in fatty acids are more oxidized than the carbons in carbohydrates.
The carbons in fatty acids are more reduced than the carbons in carbohydrates.
The carbons in fatty acids are more reduced than the carbons in carbohydrates.
Anaplerotic reactions
produce pyruvate and citrate to maintain constant levels of citric acid cycle intermediates
all of the other answers are correct
recycle pantothenate used to make CoA
Use citric acid cycle intermediates to make other useful precursors in the cell
produce citric acid cycle intermediates
produce citric acid cycle intermediates
What is the primary function of the chylomicron in absorption of fats?
It helps solubilize fats so that they can be delivered from the intestinal cells to adipocytes via the blood
phosphoryl group transfer
It is a lipase, which is an enzyme that breaks down lipids into fatty acids
It is produced in the liver and is important for gluconeogenesis
it is a coenzyme required for the Citric Acid Cycle
It helps solubilize fats so that they can be delivered from the intestinal cells to adipocytes via the blood
What is the primary function of bile?
It helps solubilize fats in the diet so that they can be broken down and absorbed into the body
it is a coenzyme required for the Citric Acid Cycle
It is produced in the liver and is important for gluconeogenesis
phosphoryl group transfer
It is a lipase, which is an enzyme that breaks down lipids into fatty acids
It helps solubilize fats in the diet so that they can be broken down and absorbed into the body
The reaction of the citric acid cycle that involves substrate-level phosphorylation forms the following metabolite as a product:
fumarate.
alphaketoglutarate
succinyl CoA
succinate
isocitrate.
succinate
Triglycerides are carried in the blood by ______ while free fatty acids in the blood bind to and are carried by _______.
Chylomicrons, Perilipins
Chylomicrons, Serum albumin
Perilipins, Serum albumin
Perilipins, Chylomicrons
Serum albumin, perilipins
Chylomicrons, Serum albumin
