Question 1

Why is the actual free energy ($\Delta$G) of hydrolysis of ATP in the cell different from the standard free energy ($\Delta$G'°)?

Accepted Answer

The actual free energy change (ΔG) of AT

Question 2

Under standard conditions, is the oxidation of free FADH2 by ubiquinone sufficiently exergonic to drive the synthesis of ATP?

Accepted Answer

A)  no ,as oxidation of FADH2 by ubiquinone generates 33.6 kJ/mol 
B)  no, as oxidation of FADH2 by ubiquinone generates 50.9 kJ/mol 
C)  no, as oxidation of FADH2 by ubiquinone generates -25.5 kJ/mol 
D)  yes, as oxidation of FADH2 by ubiquinone generates -33.6 kJ/mol 
E)  yes, as oxidation of FADH2 by ubiquinone generates -50.9 kJ/mol 
A)  no ,as oxidation of FADH2 by ubiquinone generates 33.6 kJ/mol 
B)  no, as oxidation of FADH2 by ubiquinone generates 50.9 kJ/mol 
C)  no, as oxidation of FADH2 by ubiquinone generates -25.5 kJ/mol 
D)  yes, as oxidation of FADH2 by ubiquinone generates -33.6 kJ/mol 
E)  yes, as oxidation of FADH2 by ubiquinone generates -50.9 kJ/mol

Question 3

The $\Delta$G'° values for the two reactions shown below are given. oxaloacetate + acetyl-CoA + H2O $\rightarrow$ citrate + CoASH
$\Delta$G'° = -32.2 kJ/mol
Citrate
Synthase
Oxaloacetate + acetate $\rightarrow$ citrate
$\Delta$G'° = -1.9 kJ/mol
Citrate lyase
What is the$\Delta$G'° for the hydrolysis of acetyl-CoA?
Acetyl-CoA + H2O $\rightarrow$ acetate + CoASH + H+

Accepted Answer

A)  -34.1 kJ/mol 
B)  -32.2 kJ/mol 
C)  -30.3 kJ/mol 
D)  +61.9 kJ/mol 
E)  +34.1 kJ/mol 
A)  -34.1 kJ/mol 
B)  -32.2 kJ/mol 
C)  -30.3 kJ/mol 
D)  +61.9 kJ/mol 
E)  +34.1 kJ/mol

Question 4

The hydrolysis of phosphoenolpyruvate proceeds with a $\Delta$G'° of about -62 kJ/mol. The greatest contributing factors to this reaction are the destabilization of the reactants by electostatic repulsion and stabilization of the product pyruvate by:

Accepted Answer

A)  electrostatic attraction. 
B)  ionization. 
C)  polarization. 
D)  resonance. 
E)  tautomerization. 
A)  electrostatic attraction. 
B)  ionization. 
C)  polarization. 
D)  resonance. 
E)  tautomerization.

Question 5

The standard reduction potentials (E'°) for the following half reactions are given. fumarate + 2H+ + 2e- $\rightarrow$  succinate
E'° = +0.031 V
FAD + 2H+ + 2e- $\rightarrow$ FADH2
E'° = -0.219 V
If you mixed succinate, fumarate, FAD, and FADH2 together, all at l M concentrations and in the presence of succinate dehydrogenase, what would happen initially?

Accepted Answer

A)  Fumarate and succinate would become oxidized; FAD and FADH2 would become reduced. 
B)  Fumarate would become reduced; FADH2 would become oxidized. 
C)  No reaction would occur because all reactants and products are already at their standard concentrations. 
D)  Succinate would become oxidized; FAD would become reduced. 
E)  Succinate would become oxidized; FADH2 would be unchanged because it is a cofactor. 
A)  Fumarate and succinate would become oxidized; FAD and FADH2 would become reduced. 
B)  Fumarate would become reduced; FADH2 would become oxidized. 
C)  No reaction would occur because all reactants and products are already at their standard concentrations. 
D)  Succinate would become oxidized; FAD would become reduced. 
E)  Succinate would become oxidized; FADH2 would be unchanged because it is a cofactor.

Question 6

ATP can be generated from a variety pf phosphorylated compounds via phosphate-transfer reactions. Which molecules CANNOT serve as "high-energy" phosphate donors in the synthesis of ATP?

Accepted Answer

A)  phosphate esters 
B)  acyl phosphates 
C)  phosphagens 
D)  phosphoamides 
E)  enolphosphates 
A)  phosphate esters 
B)  acyl phosphates 
C)  phosphagens 
D)  phosphoamides 
E)  enolphosphates

Question 7

Which statement is TRUE regarding $\Delta$G'?

Accepted Answer

A)  $\Delta$G' is negative when the reaction is occurring spontaneously. 
B) $\Delta$G' is zero when the rate of the forward and reverse reactions are equal. 
C)  $\Delta$G' becomes less negative as the reaction proceeds spontaneously. 
D)  All of the statements are true. 
E)  None of the statements is true. 
A)  $\Delta$G' is negative when the reaction is occurring spontaneously. 
B) $\Delta$G' is zero when the rate of the forward and reverse reactions are equal. 
C)  $\Delta$G' becomes less negative as the reaction proceeds spontaneously. 
D)  All of the statements are true. 
E)  None of the statements is true.

Question 8

Which enzyme catalyzes phosphate transfer reactions between nucleotides?

Accepted Answer

A)  nucleoside diphosphate kinase 
B)  creatine kinase 
C)  adenylate kinase 
D)  both nucleoside diphosphate kinase and adenylate kinase 
E)  both creatine kinase and adenylate kinase 
A)  nucleoside diphosphate kinase 
B)  creatine kinase 
C)  adenylate kinase 
D)  both nucleoside diphosphate kinase and adenylate kinase 
E)  both creatine kinase and adenylate kinase

Question 9

If the $\Delta$G'° of the reaction A $\rightarrow$ B is -40 kJ/mol, under standard conditions the reaction:

Accepted Answer

A)  is at equilibrium. 
B)  will never reach equilibrium. 
C)  will not occur spontaneously. 
D)  will proceed at a rapid rate. 
E)  will proceed spontaneously from A to B. 
A)  is at equilibrium. 
B)  will never reach equilibrium. 
C)  will not occur spontaneously. 
D)  will proceed at a rapid rate. 
E)  will proceed spontaneously from A to B.

Question 10

Muscle contraction involves the conversion of:

Accepted Answer

A)  chemical energy to kinetic energy. 
B)  chemical energy to potential energy. 
C)  kinetic energy to chemical energy. 
D)  potential energy to chemical energy. 
E)  potential energy to kinetic energy. 
A)  chemical energy to kinetic energy. 
B)  chemical energy to potential energy. 
C)  kinetic energy to chemical energy. 
D)  potential energy to chemical energy. 
E)  potential energy to kinetic energy.

Question 11

For the following reaction, $\Delta$G'° = +29.7 kJ/mol. L-Malate + NAD+ $\rightarrow$ oxaloacetate + NADH + H+
The reaction as written:

Accepted Answer

A)  can never occur in a cell. 
B)  can occur in a cell only if it is coupled to another reaction for which $\Delta$G'° is positive. 
C)  can occur only in a cell in which NADH is converted to NAD+ by electron transport. 
D)  cannot occur because of its large activation energy. 
E)  may occur in cells at some concentrations of substrate and product. 
A)  can never occur in a cell. 
B)  can occur in a cell only if it is coupled to another reaction for which $\Delta$G'° is positive. 
C)  can occur only in a cell in which NADH is converted to NAD+ by electron transport. 
D)  cannot occur because of its large activation energy. 
E)  may occur in cells at some concentrations of substrate and product.

Question 12

Which atom is a common electrophile?

Accepted Answer

A)  a hydrogen atom 
B)  an oxygen atom of a carbonyl group 
C)  an oxygen atom of a phosphate group 
D)  All of the answers are correct. 
E)  None of the answers is correct. 
A)  a hydrogen atom 
B)  an oxygen atom of a carbonyl group 
C)  an oxygen atom of a phosphate group 
D)  All of the answers are correct. 
E)  None of the answers is correct.

Question 13

During transfer of two electrons through the mitochondrial respiratory chain, the overall reaction is:
NADH + 1/2 O2 + H+ $\rightarrow$ NAD+ + H2O
For this reaction, the difference in reduction potentials for the two half-reactions ($\Delta$E'°) is +1.14 V. Show how you would calculate the standard free-energy change, $\Delta$G'°, for the reaction. (The Faraday constant,  , is 96.48 kJ/V · mol.)

Accepted Answer

To calculate the standard free-energy ch

Question 14

In the following reaction, which molecule is the oxidant? 1,3-bisphosphoglycerate + NADH + H+ $\rightarrow$glyceraldehyde-3-phosphate + Pi + NAD+

Accepted Answer

A)  1,3-bisphosphoglycerate 
B)  NADH 
C)  H+ 
D)  glyceraldehyde-3-phosphate 
E)  NAD+ 
A)  1,3-bisphosphoglycerate 
B)  NADH 
C)  H+ 
D)  glyceraldehyde-3-phosphate 
E)  NAD+

Question 15

Which carbon atom is in the MOST oxidized state?

Accepted Answer

A)  a carbon in an alkyl group 
B)  a carbon in a ketone group 
C)  a carbon in carbon dioxide 
D)  a carbon in a carboxylic acid group 
E)  a carbon in an alcohol group 
A)  a carbon in an alkyl group 
B)  a carbon in a ketone group 
C)  a carbon in carbon dioxide 
D)  a carbon in a carboxylic acid group 
E)  a carbon in an alcohol group

Question 16

If $\Delta$E'° for an oxidation-reduction reaction is positive, will $\Delta$G'° be positive or negative? What is the equation that relates $\Delta$G'° and $\Delta$E'°?

Accepted Answer

The symbols in the question seem to be a

Question 17

Which item is NOT electrophilic?

Accepted Answer

A)  a proton 
B)  a sulfhydryl 
C)  a protonated imine 
D)  a carbonyl group 
E)  a phosphoryl group 
A)  a proton 
B)  a sulfhydryl 
C)  a protonated imine 
D)  a carbonyl group 
E)  a phosphoryl group

Question 18

What is the equilibrium constant for the reaction shown below? glutathione + NADPH + H+ $\leftrightarrow$reduced glutathione + reduced glutathione + NADP+

Accepted Answer

A)  0.073 
B)  1.073 
C)  7.03 
D)  17.4 
E)  1,487 
A)  0.073 
B)  1.073 
C)  7.03 
D)  17.4 
E)  1,487

Question 19

Explain in quantitative terms the circumstances under which the following reaction can proceed.
citrate $\rightarrow$ isocitrate
$\Delta$G'° = +13.3 kJ/mol

Accepted Answer

The reaction in question is the isomeriz

Question 20

Biological oxidation-reduction reactions always involve:

Accepted Answer

A)  direct participation of oxygen. 
B)  formation of water. 
C)  mitochondria. 
D)  transfer of electron(s). 
E)  transfer of hydrogens. 
A)  direct participation of oxygen. 
B)  formation of water. 
C)  mitochondria. 
D)  transfer of electron(s). 
E)  transfer of hydrogens.

Exam 13: Bioenergetics and Biochemical Reaction Types

Why is the actual free energy ( Δ\DeltaΔ G) of hydrolysis of ATP in the cell different from the standard free energy ( Δ\DeltaΔ G'°)?

Under standard conditions, is the oxidation of free FADH2 by ubiquinone sufficiently exergonic to drive the synthesis of ATP?

The hydrolysis of phosphoenolpyruvate proceeds with a Δ\DeltaΔ G'° of about -62 kJ/mol. The greatest contributing factors to this reaction are the destabilization of the reactants by electostatic repulsion and stabilization of the product pyruvate by:

ATP can be generated from a variety pf phosphorylated compounds via phosphate-transfer reactions. Which molecules CANNOT serve as "high-energy" phosphate donors in the synthesis of ATP?

Which statement is TRUE regarding Δ\DeltaΔ G'?

Which enzyme catalyzes phosphate transfer reactions between nucleotides?

If the Δ\DeltaΔ G'° of the reaction A →\rightarrow→ B is -40 kJ/mol, under standard conditions the reaction:

Muscle contraction involves the conversion of:

For the following reaction, Δ\DeltaΔ G'° = +29.7 kJ/mol. L-Malate + NAD+ →\rightarrow→ oxaloacetate + NADH + H+ The reaction as written:

Which atom is a common electrophile?

In the following reaction, which molecule is the oxidant? 1,3-bisphosphoglycerate + NADH + H+ →\rightarrow→ glyceraldehyde-3-phosphate + Pi + NAD+

Which carbon atom is in the MOST oxidized state?

If Δ\DeltaΔ E'° for an oxidation-reduction reaction is positive, will Δ\DeltaΔ G'° be positive or negative? What is the equation that relates Δ\DeltaΔ G'° and Δ\DeltaΔ E'°?

Which item is NOT electrophilic?

What is the equilibrium constant for the reaction shown below? glutathione + NADPH + H+ ↔\leftrightarrow↔ reduced glutathione + reduced glutathione + NADP+

Explain in quantitative terms the circumstances under which the following reaction can proceed. citrate →\rightarrow→ isocitrate Δ\DeltaΔ G'° = +13.3 kJ/mol

Biological oxidation-reduction reactions always involve:

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Why is the actual free energy ( $\Delta$ G) of hydrolysis of ATP in the cell different from the standard free energy ( $\Delta$ G'°)?

Under standard conditions, is the oxidation of free FADH₂ by ubiquinone sufficiently exergonic to drive the synthesis of ATP?

The hydrolysis of phosphoenolpyruvate proceeds with a $\Delta$ G'° of about -62 kJ/mol. The greatest contributing factors to this reaction are the destabilization of the reactants by electostatic repulsion and stabilization of the product pyruvate by:

Which statement is TRUE regarding $\Delta$ G'?

If the $\Delta$ G'° of the reaction A $\rightarrow$ B is -40 kJ/mol, under standard conditions the reaction:

For the following reaction, $\Delta$ G'° = +29.7 kJ/mol. L-Malate + NAD⁺ $\rightarrow$ oxaloacetate + NADH + H⁺ The reaction as written:

In the following reaction, which molecule is the oxidant? 1,3-bisphosphoglycerate + NADH + H⁺ $\rightarrow$ glyceraldehyde-3-phosphate + P_i + NAD⁺

If $\Delta$ E'° for an oxidation-reduction reaction is positive, will $\Delta$ G'° be positive or negative? What is the equation that relates $\Delta$ G'° and $\Delta$ E'°?

What is the equilibrium constant for the reaction shown below? glutathione + NADPH + H⁺ $\leftrightarrow$ reduced glutathione + reduced glutathione + NADP⁺

Explain in quantitative terms the circumstances under which the following reaction can proceed. citrate $\rightarrow$ isocitrate $\Delta$ G'° = +13.3 kJ/mol