Question 1

What is an oxidation? What is a reduction? Can an oxidation occur without a simultaneous reduction? Why or why not?

Accepted Answer

Oxidation is the loss of electrons;reduc

Question 2

Bioenergetics and thermodynamics
What is the difference between$\Delta$G and$\Delta$G'° of a chemical reaction? Describe,quantitatively,the relationship between them.

Accepted Answer

@#LAT-DLM&G'° is the difference in free energies o

Question 3

Biological oxidation-reduction reactions never involve:

Accepted Answer

A) transfer of e- from one molecule to another. 
B) formation of free e-. 
C) transfer of H+ (or H3O+)from one molecule to another. 
D) formation of free H+ (or H3O+). 
E) none of the above. 
A) transfer of e- from one molecule to another. 
B) formation of free e-. 
C) transfer of H+ (or H3O+)from one molecule to another. 
D) formation of free H+ (or H3O+). 
E) none of the above.

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

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 concentrations of the reactant (ATP)

Question 6

If a 0.1 M solution of glucose 1-phosphate is incubated with a catalytic amount of phospho-glucomutase,the glucose 1-phosphate is transformed to glucose 6-phosphate until equilibrium is reached.At equilibrium,the concentration of glucose 1-phosphate is 4.5 x 10-3 M and that of glucose 6-phosphate is 8.6 *10-2 M.Set up the expressions for the calculation of Keq' and$\Delta$G'° for this reaction (in the direction of glucose 6-phosphate formation).(R = 8.315 J/mol·K;T = 298 K)

Accepted Answer

The answer of If a 0.1 M solution of glucose...

Question 7

Which of the following 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 8

The structure of NAD+ does not include:

Accepted Answer

A) a flavin nucleotide. 
B) a pyrophosphate bond. 
C) an adenine nucleotide. 
D) nicotinamide. 
E) two ribose residues. 
A) a flavin nucleotide. 
B) a pyrophosphate bond. 
C) an adenine nucleotide. 
D) nicotinamide. 
E) two ribose residues.

Question 9

Which of the following is not true for the nicotinamide cofactors?

Accepted Answer

A) The oxidized form is positively charged. 
B) The reduced form has a large extinction coefficient at 340 nm. 
C) The oxidized form provides reducing equivalents to other molecules. 
D) Oxidation-reduction reactions with nicotinamides usually involve hydride transfer. 
E) Enzymes transfer hydrides stereospecifically to one or the other side of the nicotinamide ring. 
A) The oxidized form is positively charged. 
B) The reduced form has a large extinction coefficient at 340 nm. 
C) The oxidized form provides reducing equivalents to other molecules. 
D) Oxidation-reduction reactions with nicotinamides usually involve hydride transfer. 
E) Enzymes transfer hydrides stereospecifically to one or the other side of the nicotinamide ring.

Question 10

For the reaction A $\rightarrow$ B,$\Delta$G'° = -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?

Accepted Answer

A) A and B have reached equilibrium concentrations. 
B) An enzyme has shifted the equilibrium toward A. 
C) B formation is kinetically slow;equilibrium has not been reached by 24 hours. 
D) Formation of B is thermodynamically unfavorable. 
E) The result described is impossible,given the fact that$\Delta$G'° is -60 kJ/mol. 
A) A and B have reached equilibrium concentrations. 
B) An enzyme has shifted the equilibrium toward A. 
C) B formation is kinetically slow;equilibrium has not been reached by 24 hours. 
D) Formation of B is thermodynamically unfavorable. 
E) The result described is impossible,given the fact that$\Delta$G'° is -60 kJ/mol.

Question 11

The$\Delta$G'° values for the two reactions shown below are given.
 
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 12

Which of the following compounds has the largest negative value for the standard free-energy change ($\Delta$G'°)upon hydrolysis?

Accepted Answer

A) Acetic anhydride 
B) Glucose 6-phosphate 
C) Glutamine 
D) Glycerol 3-phosphate 
E) Lactose 
A) Acetic anhydride 
B) Glucose 6-phosphate 
C) Glutamine 
D) Glycerol 3-phosphate 
E) Lactose

Question 13

Explain why each of the following statements is false.
(a)In a reaction under standard conditions,only the reactants are fixed at 1 M.
(b)When$\Delta$G'° is positive,Keq' > 1.
(c)$\Delta$G and$\Delta$G'° mean the same thing.
(d)When$\Delta$G'° = 1.0 kJ/mol,Keq' = 1.

Accepted Answer

(a)Both reactants and products are fixed

Question 14

In glycolysis,fructose 1,6-bisphosphate is converted to two products with a standard free-energy change ($\Delta$ G'°)of 23.8 kJ/mol.Under what conditions encountered in a normal cell will the free-energy change ($\Delta$ G)be negative,enabling the reaction to proceed spontaneously to the right?

Accepted Answer

A) Under standard conditions,enough energy is released to drive the reaction to the right. 
B) The reaction will not go to the right spontaneously under any conditions because the$\Delta$ G'° is positive. 
C) The reaction will proceed spontaneously to the right if there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate. 
D) The reaction will proceed spontaneously to the right if there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products. 
E) None of the above conditions is sufficient. 
A) Under standard conditions,enough energy is released to drive the reaction to the right. 
B) The reaction will not go to the right spontaneously under any conditions because the$\Delta$ G'° is positive. 
C) The reaction will proceed spontaneously to the right if there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate. 
D) The reaction will proceed spontaneously to the right if there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products. 
E) None of the above conditions is sufficient.

Question 15

The standard free energy change ($\Delta$G'°)for ATP hydrolysis is -30.5 kJ/mol.ATP,ADP,and Pi are mixed together at initial concentrations of 1 M of each,then left alone until the reaction ADP + Pi $\rightarrow$ ATP has come to equilibrium.For each species (i.e. ,ATP,ADP,and Pi),indicate whether the concentration will be equal to 1 M,less than 1 M,or greater than 1 M.

Accepted Answer

At equilibrium,ATP <

Question 16

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 17

Alcohol dehydrogenase catalyzes the following reversible reaction:
Acetaldehyde + NADH + H+ $\rightarrow$ Ethanol + NAD+
Use the following information to answer the questions below:
 
The Faraday constant,   ,is 96.48 kJ/V·mol.
(a)Calculate$\Delta$G'° for the reaction as written.Show your work.
(b)Given your answer to (a),what is the$\Delta$G'° for the reaction occurring in the reverse direction?
(c)Which reaction (forward or reverse)will tend to occur spontaneously under standard conditions?
(d)In the cell,the reaction actually proceeds in the direction that has a positive$\Delta$G'°.Explain how this could be possible.

Accepted Answer

(a)@#LAT-DLM&G'° = E'°(acceptor)- E'°(donor)= -0.2

Question 18

Hydrolysis of 1 M glucose 6-phosphate catalyzed by glucose 6-phosphatase is 99% complete at equilibrium (i.e. ,only 1% of the substrate remains).Which of the following statements is most nearly correct? (R = 8.315 J/mol·K;T = 298 K)

Accepted Answer

A) ($\Delta$G'° is -11 kJ/mol.) 
B) ($\Delta$G'° is -5 kJ/mol.) 
C) ($\Delta$G'° is 0 kJ/mol.) 
D) ($\Delta$G'° is +11 kJ/mol.) 
E) ($\Delta$G'° cannot be determined from the information given.) 
A) ($\Delta$G'° is -11 kJ/mol.) 
B) ($\Delta$G'° is -5 kJ/mol.) 
C) ($\Delta$G'° is 0 kJ/mol.) 
D) ($\Delta$G'° is +11 kJ/mol.) 
E) ($\Delta$G'° cannot be determined from the information given.)

Question 19

In general,when ATP hydrolysis is coupled to an energy-requiring reaction,the actual reaction often consists of the transfer of a phosphate group from ATP to another substrate,rather than an actual hydrolysis of the ATP.Explain.

Accepted Answer

Hydrolysis of the ATP would result in th

Question 20

Lactate dehydrogenase catalyzes the reversible reaction:
Pyruvate + NADH + H+ $\rightarrow$Lactate + NAD+
Given the following facts 
(a)tell in which direction the reaction will tend to go if NAD+,NADH,pyruvate,and lactate were mixed,all at 1 M concentrations,in the presence of lactate dehydrogenase at pH 7; (b)calculate$\Delta$G'° for this reaction.Show your work.

Accepted Answer

@#LAT-DLM&G'° = E'°(acceptor)- E'°(donor

Exam 13: Principles of Bioenergetics

What is an oxidation? What is a reduction? Can an oxidation occur without a simultaneous reduction? Why or why not?

Bioenergetics and thermodynamics What is the difference between Δ\DeltaΔ G and Δ\DeltaΔ G'° of a chemical reaction? Describe,quantitatively,the relationship between them.

Biological oxidation-reduction reactions never involve:

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:

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'°)?

Which of the following is not electrophilic?

The structure of NAD+ does not include:

Which of the following is not true for the nicotinamide cofactors?

For the reaction A →\rightarrow→ B, Δ\DeltaΔ G'° = -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?

The Δ\DeltaΔ G'° values for the two reactions shown below are given. What is the Δ\DeltaΔ G'° for the hydrolysis of acetyl-CoA? Acetyl-CoA + H2O →\rightarrow→ acetate + CoASH + H+

Which of the following compounds has the largest negative value for the standard free-energy change ( Δ\DeltaΔ G'°)upon hydrolysis?

Explain why each of the following statements is false. (a)In a reaction under standard conditions,only the reactants are fixed at 1 M. (b)When Δ\DeltaΔ G'° is positive,Keq' > 1. (c) Δ\DeltaΔ G and Δ\DeltaΔ G'° mean the same thing. (d)When Δ\DeltaΔ G'° = 1.0 kJ/mol,Keq' = 1.

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

Hydrolysis of 1 M glucose 6-phosphate catalyzed by glucose 6-phosphatase is 99% complete at equilibrium (i.e. ,only 1% of the substrate remains).Which of the following statements is most nearly correct? (R = 8.315 J/mol·K;T = 298 K)

In general,when ATP hydrolysis is coupled to an energy-requiring reaction,the actual reaction often consists of the transfer of a phosphate group from ATP to another substrate,rather than an actual hydrolysis of the ATP.Explain.

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

Recombinant Dna Technology

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

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Bioenergetics and thermodynamics What is the difference between $\Delta$ G and $\Delta$ G'° of a chemical reaction? Describe,quantitatively,the relationship between them.

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:

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

The structure of NAD⁺ does not include:

For the reaction A $\rightarrow$ B, $\Delta$ G'° = -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?

Which of the following compounds has the largest negative value for the standard free-energy change ( $\Delta$ G'°)upon hydrolysis?

Explain why each of the following statements is false. (a)In a reaction under standard conditions,only the reactants are fixed at 1 M. (b)When $\Delta$ G'° is positive,K_eq' > 1. (c) $\Delta$ G and $\Delta$ G'° mean the same thing. (d)When $\Delta$ G'° = 1.0 kJ/mol,K_eq' = 1.

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