Chapter 14
Which of the following must be true for A + B+ to be converted to A+ + B? Entry field with correct answer A positive ΔG A positive ΔG and negative ΔE A negative ΔE A positive ΔE and positive ΔG A positive ΔE
A positive ΔE
Which of the following are factors that contribute to the large negative standard free energy change for the reaction shown below? ATP ADP + Pi Entry field with correct answer the increase in resonance stabilization in the reactants compare to the products the precipitation of the insoluble Pi the addition of a water molecule to the hydrophilic ATP molecule the decrease in negative charge repulsion in the products compared to reactants all of the above
the decrease in negative charge repulsion in the products compared to reactants
Consider the following metabolic reaction important in muscle and nerve cells: ATP + creatine phosphocreatine + ADP = +12.6 kJ/mol Under intracellular conditions, the for the reaction, which is catalyzed by the enzyme creatine kinase, is ~0 kJ/mol. From this information we can conclude that Entry field with correct answer creatine kinase catalysis would not be necessary under intracellular conditions. ATP has a greater phosphoryl group transfer potential compared to phosphocreatine. at equilibrium, most intracellular creatine is phosphorylated. the reaction operates close to equilibrium in cells. None of the above is a correct conclusion.
the reaction operates close to equilibrium in cells.
Acetyl-CoA contains a ____ bond which often provides the energy required for substrate-level phosphorylation. Entry field with correct answer phosphoester phosphoanhydride phosphothioester ester thioester
thioester
Negative feedback inhibition is one type of _______ metabolic control. Entry field with correct answer allosteric hormonal covalent modification genetic signal transduction
allosteric
The Keq is 0.503 at 25°C for the following reaction. What is the for this reaction? D-Glucose-6-phosphate D-Fructose-6-phosphate = ? Entry field with correct answer -2.87 × 103 J/mol. +1.70 kJ/mol. +143 J/mol. The cannot be determined with the given information. The can be determined with the given information but the correct answer is not shown.
+1.70 kJ/mol.
Given that the standard reduction potential of oxaloacetate is -0.166 V and the standard reduction potential of NAD+ is -0.315 V. What is the for the oxidation of malate by NAD+: Malate + NAD+ Oxaloacetate + NADH + H+ Entry field with correct answer -4.81 V + 4.81 V -0.149 V +0.149 V +0.052 V
-0.149 V
Consider the following metabolic reaction: 3-Phosphoglycerate 2-Phosphoglycerate = +4.40 kJ/mol What is the for this reaction when the concentration of 2-phosphoglycerate is 0.290 mM and the concentration of 3-phosphoglycerate is 2.90 mM at 37°C? Entry field with correct answer +10.3 kJ/mol -1.53 kJ/mol -1.30 kJ/mol -5.93 kJ/mol -4.40 kJ/mol
-1.53 kJ/mol
If the ∆G0' for hydrolysis of glucose-1-phosphate is -13.8 kJ/mol, and for hydrolysis of ATP is -30.5 kJ/mol, what will be the ΔG¡' for the phosphorylation of glucose by ATP to produce glucose-1-phosphate? Entry field with correct answer +44.3 kJ/mol -16.7 kJ/mol +16.7 kJ/mol -44.3 kJ/mol
-16.7 kJ/mol
Consider the following metabolic reaction: Succinyl-CoA + Acetoacetate -> Acetoacetyl-CoA + Succinate = -1.25 kJ/mol The for the hydrolysis of Succinyl-CoA is -33.9 kJ/mol. What is the for the hydrolysis of Acetoacetyl-CoA: Acetoacetyl-CoA Acetoacetate + CoA Entry field with correct answer -35.2 kJ/mol -32.7 kJ/mol +32.7 kJ/mol +35.2 kJ/mol none of the above
-32.7 kJ/mol
Under standard conditions, the free energy change for the hydrolysis of phosphoarginine is - 32 kJ/mol. What is the actual free-energy change for the reaction at 25oC and pH 7.0 where the concentrations of phosphoarginine, arginine and Pi are 6.8 mM, 2.6 mM and 5 mM, respectively? Entry field with correct answer -16.5 kJ/mol -30.4 kJ/mol -13.3 kJ/mol -47.5 kJ/mol -50.7 kJ/mol
-47.5 kJ/mol
Under standard conditions the free energy change for the hydrolysis of ATP is - 31 kJ/mol. What is the actual free-energy change for the reaction at 37oC and pH 7.0, where the concentrations of ATP, ADP and Pi are 8.8 mM, 1.3 mM and 5.5 mM, respectively? Entry field with correct answer -25.7 kJ/mol -49.3 kJ/mol -12.7 kJ/mol -36.4 kJ/mol
-49.3 kJ/mol
Consider the following metabolic reaction: Succinyl-CoA + Acetoacetate Acetoacetyl-CoA + Succinate = -1.25 kJ/mol What is the Keq for this reaction at 25°C? Entry field with correct answer 1.66 0.602 1.00 4.22 x 102 3.21
1.66
What is the Keq for the energetically favourable reaction A + B ―> C when its standard free energy change is -25kJ/mol? Entry field with correct answer 1.6 x 104 1.01 1.2 x 1010 4.1 x 10-5 2.41 x 104
2.41 x 104 The formula for this calculation is ΔGo'= - RT ln Keq
Which of the following best describes a typical metabolic pathway? Entry field with correct answer A series of enzyme-catalyzed steps, most of which are operating near equilibrium, but one or more is highly favorable and irreversible A series of enzyme-catalyzed steps, all of which are highly favorable, and irreversible A series of enzyme-catalyzed steps, all of which are operating near equilibrium A series of enzyme-catalyzed steps, most of which are highly favorable, but one or more is near equilibrium
A series of enzyme-catalyzed steps, most of which are operating near equilibrium, but one or more is highly favorable and irreversible
Which of the following is NOT a high energy intermediate of metabolism? Entry field with correct answer Thioesters NADPH AMP ATP All of the above are high energy intermediates.
AMP
Where does ATP hydrolysis rank among the standard free energies of phosphoryl group transfer of all biological molecules? Entry field with correct answer ATP hydrolysis has the largest negative free energy change. ATP hydrolysis has nearly the largest negative free energy change. ATP hydrolysis has an intermediate free energy change. ATP hydrolysis has nearly the smallest negative free energy change.
ATP hydrolysis has an intermediate free energy change.
Which of the following features are common to all anabolic pathways? Entry field with correct answer They break down complex molecules. They require energy. They are oxidative. Their overall free energy change is positive
They require energy.
If Z = ATP formed via substrate level phosphorylation in the diagram below, which of the following compounds (represented by an uppercase letter) contains a high-energy bond? Entry field with correct answer Compound A Compound B Compound C All have equally high energy. All have equally low energy.
Compound B
Which of the following bonds or functional groups is NOT found in ADP? Entry field with correct answer Neither a phosphoester bond nor deoxyribose A purine base A phosphoanhydride bond A phosphoester bond Deoxyribose
Deoxyribose
How do electrostatic interactions contribute to the free energy of hydrolysis of ATP? Entry field with correct answer Electrostatic repulsion destabilizes ATP relative to the hydrolysis products, and therefore makes hydrolysis favorable. They have little effect since ATP, ADP and Pi are all negatively charged. Electrostatic attraction destabilizes ATP relative to the hydrolysis products, and therefore makes hydrolysis favorable. Electrostatic repulsion stabilizes ATP, and therefore makes hydrolysis less favorable.
Electrostatic repulsion destabilizes ATP relative to the hydrolysis products, and therefore makes hydrolysis favorable
Which of the following is a long term control mechanism? Entry field with correct answer Covalent modification Allosteric control Substrate cycles Genetic control
Genetic control
Which of the following phosphorylated compounds would be considered a "low-energy" intermediate in metabolism, relative to the others? Entry field with correct answer Glucose-6-phosphate ATP Phosphocreatine Phosphoenolpyruvate 1,3-Bisphosphoglycerate
Glucose-6-phosphate
The ∆Go' for the phosphorylation of creatine by ATP is +12.6 kJ/mol. How does this reaction proceed inside the cell? Entry field with correct answer It proceeds spontaneously because the ∆Go' is positive. It proceeds because of the enzyme creatine kinase. It proceeds because of the enzyme creatine kinase, and because the concentrations of the reactants and products makes ∆G approximately zero. This reaction cannot proceed.
It proceeds because of the enzyme creatine kinase, and because the concentrations of the reactants and products makes ∆G approximately zero.
What is one of the advantages of the presence of different catabolic and anabolic pathways? Entry field with correct answer It is not important, but arose by evolutionary accident. Few enzymes are capable of operating in both directions. It prevents coordinated regulation. It allows for independent regulation of the two pathways.
It allows for independent regulation of the two pathways.
Why is acetyl-CoA considered a high energy molecule? Entry field with correct answer Large amounts of ATP are released upon deacetylation. Large amounts of ATP are released upon oxidation. It contains an ester bond. It contains a thioester bond.
It contains a thioester bond.
What characterizes the rate-determining step of a metabolic pathway? Entry field with correct answer It functions near equilibrium and it has a large negative free energy change. It functions far from equilibrium and it has a large negative free energy change. It functions near equilibrium and it has a large positive free energy change. It functions far from equilibrium and it has a large positive free energy change.
It functions far from equilibrium and it has a large negative free energy change.
Which of the following statements concerning metabolic pathways is TRUE? Entry field with correct answer Metabolic pathways may have either a net positive or net negative free energy. Many of the reactions in a metabolic pathway are thermodynamically reversible. Opposing metabolic pathways do NOT occur. All reactions in a metabolic pathway are tightly regulated.
Many of the reactions in a metabolic pathway are thermodynamically reversible.
Under standard conditions is the oxidation of NADH by pyruvate sufficiently exergonic to drive the synthesis of ATP? Pick the statement below which best answers this question. Entry field with incorrect answer No, because the oxidation of NADH by pyruvate only generates -25.1 kJ/mol of energy. No, because the oxidation of NADH by pyruvate requires 25.1 kJ/mol of energy, which is endergonic. Yes, because the oxidation of NADH by pyruvate generates -96.5 kJ/mol of energy. Yes, because the oxidation of NADH by pyruvate generates 96.5 kJ/mol of energy.
No, because the oxidation of NADH by pyruvate only generates -25.1 kJ/mol of energy.
The enzyme inorganic pyrophosphatase catalyzes the hydrolysis of bonds in ___. Entry field with correct answer ATP ADP AMP PPi phosphate
PPi
Use the table below to rank the redox centers in order of increasing ability to produce a favorable electron flow. Redox Center ε°' D - 0.002 F - 0.198 Q - 0.225 C - 0.053 Z + 0.002 Entry field with correct answer D, Q, F, C, Z Q, F, C, D, Z Z, Q, F, C, D Z, F, C, D, Q Z, Q, C, Q, D
Q, F, C, D, Z
The standard free energy change for the hydrolysis of ATP to ADP and inorganic phosphate (Pi) is about -30 kJ/mol but in the red blood cell the actual free energy change for this reaction is about -52 kJ/mol. This means that: Entry field with correct answer The concentration of ATP is more than 1 M. The concentration of inorganic phosphate is much lower that that of ADP. The product of the concentrations of ADP and Pi is greater than the concentration of ATP. The concentration of ATP is greater than the product of the concentrations of ADP and Pi.
The concentration of ATP is greater than the product of the concentrations of ADP and Pi.
What MOST LIKELY happens if the concentration of metabolite C is increased? Entry field with correct answer The flux through the pathway from C to E will increase. The increased concentration of C will feed-forward activate enzyme E4. The reverse reaction C to B will be driven to equilibrium. The increased concentration of C will feedback inhibit enzyme E1.
The flux through the pathway from C to E will increase.
Which of the following statements concerning ATP is TRUE? Entry field with correct answer The formation of phosphoanhydride bonds in ATP relieves electrostatic repulsion. The phosphoanhydride bonds in ATP are "high energy bonds" that are different from other covalent bonds. The hydrolysis of phosphoanhydride bonds in ATP releases large amounts of free energy. Phosphate groups within ATP experience more resonance stabilization than free phosphate groups.
The hydrolysis of phosphoanhydride bonds in ATP releases large amounts of free energy.
Which of the following statements concerning ATP is FALSE? Entry field with correct answer Phosphate groups within ATP experience less resonance stabilization than free phosphate groups. The cleavage of phosphoanhydride bonds in ATP relieves electrostatic repulsion. The phosphoanhydride bonds in ATP are "high energy bonds" that are different from other covalent bonds. The hydrolysis of phosphoanhydride bonds in ATP releases large amounts of free energy.
The phosphoanhydride bonds in ATP are "high energy bonds" that are different from other covalent bonds.
Which of the following is FALSE for catabolic pathways? Entry field with correct answer They generate oxidized enzyme cofactors. They extract usable chemical energy from fuel molecules. They are oxidative. They generate ATP.
They generate oxidized enzyme cofactors.
Which of the following best describes the flux of metabolites through a highly exergonic step? Entry field with correct answer The rates of the forward and the reverse steps are both very high. The rate of the reverse step is much greater than that of the forward step. The rates of the forward and the reverse steps are approximately equal. The rate of the forward step is much greater than that of the reverse step.
The rate of the forward step is much greater than that of the reverse step.
How does the standard state free energy of hydrolysis of ATP compare to an estimate of the free energy of ATP hydrolysis under "typical" cellular conditions? Entry field with correct answer The standard state value is -30.5 kJ/mol, but under cellular conditions it is about -50 kJ/mol. The standard state value is +30.5 kJ/mol, but under cellular conditions it is about +50 kJ/mol. The standard state value is -30.5 kJ/mol, but under cellular conditions it is about +50 kJ/mol. The standard state value is -50.5 kJ/mol, but under cellular conditions it is about -30 kJ/mol.
The standard state value is -30.5 kJ/mol, but under cellular conditions it is about -50 kJ/mol.
Why is the term "high-energy" bond somewhat of a misnomer in reference to ATP and similar compounds? Entry field with correct answer The term "high-energy" refers to the difference in free energy between the compound and it hydrolyzed product. It does not refer to the bonds energy. These bonds are actually intermediate in energy. These compounds are highly charged. These bonds require a large amount of energy to break, but do not contain a large amount of energy.
The term "high-energy" refers to the difference in free energy between the compound and it hydrolyzed product. It does not refer to the bonds energy.
Which of the following statements about FAD and NAD+ is FALSE? Entry field with correct answer They are dinucleotides. They each can reversibly carry two electrons. They are nucleic acids. They each contain a base derived from a vitamin. They each contain adenosine.
They are nucleic acids. This statement is false. Nucleic acids are polymers of nucleotides joined by phosphodiester bonds between the 3' and 5' positions of neighboring ribose units. The dinucleotides, FAD and NAD+ are each composed of two nucleotide units that are linked together by a phosphoanhydride bond
What is the role of phosphocreatine in muscle? Entry field with correct answer To make glucose in gluconeogenesis. To use in place of ATP. To make more ATP. To act as an electron carrier.
To make more ATP. Phosphocreatine is important as a source of ATP in short-term, anaerobic bursts of muscular activity. Phosphocreatine under certain cellular conditions has a greater free energy change for hydrolysis than ATP. Therefore, phosphocreatine can be used to "drive" the formation of ATP (by coupling hydrolysis of phosphocreatine with synthesis of ATP).
In the catabolic pathway major nutrients are _________ broken down resulting in the synthesis of __________ . Entry field with correct answer exergonically; ADP endergonically; ADP exergonically; ATP endergonically; NADP+ endergonically; ATP
exergonically; ATP
Organisms that can grow in either the presence or absence of oxygen are classified as Entry field with correct answer obligate aerobes facultative anaerobes autotrophs heterotrophs obligate anaerobes
facultative anaerobes
Consider the following metabolic reaction: Succinyl-CoA + Acetoacetate Acetoacetyl-CoA + Succinate = -1.25 kJ/mol This reaction is Entry field with correct answer favorable under standard conditions. not favorable under standard conditions. nonspontaneous as written regardless of reactant concentrations. spontaneous as written only when [succinate] and [acetoacetyl-CoA] are high. favorability of this reaction as written depends on temperature and reactant concentrations.
favorable under standard conditions.
The ______ is equal to the rate of synthesis minus the rate of breakdown of the metabolic intermediates. Entry field with correct answer metabolic rate Keq rate determining step flux none of the above
flux
Acyl phosphates such as 1,3-bisphosphoglycerate have a ______ phosphoryl group transfer potential compared to ATP, which can be recognized by the _______ values for hydrolysis. Entry field with correct answer greater; more positive greater; more negative lower; more positive lower; more negative none of the above
greater; more negative
NADH is a derivative of Entry field with correct answer niacin. riboflavin. lipoic acid. thiamine. vitamin A.
niacin.
Obligate aerobes Entry field with correct answer perish under conditions with O2. use oxidizing agents such as sulfate or nitrate as a primary food source. resemble the earliest life forms. all of the above none of the above
none of the above
ATP contains ________ bonds. Entry field with correct answer one phosphoanhydride and two phosphoester two phosphoester and one glycosidic three phosphoanhydride one amide and three phosphoanhydride one phosphoester and two phosphoanhydride
one phosphoester and two phosphoanhydride
∆Go' for the hydrolysis of ATP is - 31 kJ/mol. What effect will doubling ATP concentration have on the value of ∆Go' for ATP hydrolysis? Entry field with correct answer It will increase ΔGo' ΔGo' will not change It will decrease ΔGo'
ΔGo' will not change
What characterizes a spontaneous redox reaction? Entry field with correct answer ∆E (emf) is negative and ∆G is positive. ∆E is positive and ∆G is negative. ∆E (emf) is positive and ∆G is positive. ∆E (emf) is negative and ∆G is negative
∆E is positive and ∆G is negative.
