Question 1

Which of the following is NOT correct regarding non-competitive inhibition?

Accepted Answer

A) Non-competitive inhibitors interact with the enzyme as well as the enzyme-substrate complex. 
B) Increasing the concentration of [S] can overcome the inhibition. 
C) The Vmax value does not remain the same as for a reaction that is not inhibited. 
D) The inhibitor can cause a conformational change in the enzyme. 
A) Non-competitive inhibitors interact with the enzyme as well as the enzyme-substrate complex. 
B) Increasing the concentration of [S] can overcome the inhibition. 
C) The Vmax value does not remain the same as for a reaction that is not inhibited. 
D) The inhibitor can cause a conformational change in the enzyme. B

Question 2

Against which type of antigen is a catalytic antibody (abzyme)generated?

Accepted Answer

A) an analog of the transition-state intermediate in the reaction 
B) the substrate of the reaction 
C) an analog of the product of the reaction 
D) an analog of the transition-state intermediate in the reaction. 
A) an analog of the transition-state intermediate in the reaction 
B) the substrate of the reaction 
C) an analog of the product of the reaction 
D) an analog of the transition-state intermediate in the reaction. A

Question 3

What is the definition of the free energy of activation,∆G‡?

Accepted Answer

A) the average free energy of the product formed 
B) the rate of a chemical reaction in relationship to the concentration of reactant molecules 
C) the energy required to raise the average energy of one mole of reactant to the transition state energy 
D) the amount of energy released by a spontaneous reaction 
A) the average free energy of the product formed 
B) the rate of a chemical reaction in relationship to the concentration of reactant molecules 
C) the energy required to raise the average energy of one mole of reactant to the transition state energy 
D) the amount of energy released by a spontaneous reaction C

Question 4

For an enzyme-catalyzed reaction,the initial velocity was determined at 2 different concentrations of the substrate.Which of the following would be closest to the value of Vmₐₓ?

Accepted Answer

A) 0.32 mM/min 
B) 0.67 mM/min 
C) 1.5 mM/min 
D) 3.19 mM/min 
A) 0.32 mM/min 
B) 0.67 mM/min 
C) 1.5 mM/min 
D) 3.19 mM/min

Question 5

Which of the following is a feature of uncompetitive inhibition?

Accepted Answer

A) I combines only with ES. 
B) I combines only with E. 
C) I combines with E and ES. 
D) I combines with EP. 
A) I combines only with ES. 
B) I combines only with E. 
C) I combines with E and ES. 
D) I combines with EP.

Question 6

Which of the following is NOT correct regarding enzyme pathways?

Accepted Answer

A) The most effective way to control the pathway is to regulate every enzyme in the pathway. 
B) An enzyme pathway always proceeds in only one direction,never in reverse. 
C) A regulatory enzyme is regulated only by molecules within the given pathway. 
D) Metabolic pathways are necessary since enzymes usually catalyze only one specific reaction. 
A) The most effective way to control the pathway is to regulate every enzyme in the pathway. 
B) An enzyme pathway always proceeds in only one direction,never in reverse. 
C) A regulatory enzyme is regulated only by molecules within the given pathway. 
D) Metabolic pathways are necessary since enzymes usually catalyze only one specific reaction.

Question 7

A plot of 1/V versus 1/[S] for an enzyme-catalyzed reaction gave a line with an equation of y = 0.5x + 0.2.The same enzyme with an inhibitor present gave a line with an equation of y = 1.1x + 0.2.Which of these statements is correct regarding the inhibition?

Accepted Answer

A) It is competitive. 
B) It is non-competitive. 
C) It is uncompetitive. 
D) It is irreversible. 
A) It is competitive. 
B) It is non-competitive. 
C) It is uncompetitive. 
D) It is irreversible.

Question 8

Which term defines the catalytically active complex of an apoenzyme and its prosthetic group?

Accepted Answer

A) catalytic duo 
B) holoenzyme 
C) prosthetic enzyme 
D) dimeric enzyme 
A) catalytic duo 
B) holoenzyme 
C) prosthetic enzyme 
D) dimeric enzyme

Question 9

Which of the following is correct regarding the Michaelis-Menten constant,Km,for this kinetic mechanism?

Accepted Answer

A) Km is numerically equal to the substrate concentration required to achieve one half the maximum velocity. 
B) Its defined as Km = k1/(k-1 + k2). 
C) Km is approximately equal to the dissociation constant for the enzyme-substrate complex to E + P. 
D) The numeric value of Km has the units of mole-1. 
A) Km is numerically equal to the substrate concentration required to achieve one half the maximum velocity. 
B) Its defined as Km = k1/(k-1 + k2). 
C) Km is approximately equal to the dissociation constant for the enzyme-substrate complex to E + P. 
D) The numeric value of Km has the units of mole-1.

Question 10

In the enzyme catalyzed reaction sequence below,can the E-PO₄- intermediate be predicted and why?

Accepted Answer

A) Yes,the mechanism is a double-displacement reaction. 
B) Yes,the reaction fits the Ping-Pong model. 
C) No,the reaction is random single displacement. 
D) No,the reaction is double displacement. 
A) Yes,the mechanism is a double-displacement reaction. 
B) Yes,the reaction fits the Ping-Pong model. 
C) No,the reaction is random single displacement. 
D) No,the reaction is double displacement.

Question 11

Which of the following is NOT a distinctive feature of enzymes?

Accepted Answer

A) regulatory 
B) catalytic activity 
C) ability to change ∆G 
D) specificity 
A) regulatory 
B) catalytic activity 
C) ability to change ∆G 
D) specificity

Question 12

What is the basis for the International Units of an enzyme?

Accepted Answer

A) ratio of enzyme to other proteins 
B) micromoles of product formed per minute 
C) moles of substrate reacted 
D) micromoles of product produced at Vmax/2 
A) ratio of enzyme to other proteins 
B) micromoles of product formed per minute 
C) moles of substrate reacted 
D) micromoles of product produced at Vmax/2

Question 13

Which of the following is NOT correct for catalysts?

Accepted Answer

A) They work by lowering the energy of activation. 
B) The average energy of the reaction is unchanged. 
C) They combine transiently with the reactants,promoting a reactive transition state condition. 
D) They are regenerated after each third reaction cycle. 
A) They work by lowering the energy of activation. 
B) The average energy of the reaction is unchanged. 
C) They combine transiently with the reactants,promoting a reactive transition state condition. 
D) They are regenerated after each third reaction cycle.

Question 14

If an enzyme has a Vmₐₓ of 15 mM/min,what is the velocity if the substrate is present at ¼ of the Km?

Accepted Answer

A) 12 mM/min 
B) 6 mM/min 
C) 3.75 mM/min 
D) 3 mM/min 
A) 12 mM/min 
B) 6 mM/min 
C) 3.75 mM/min 
D) 3 mM/min

Question 15

What term describes an enzyme that is an ATP-dependent phosphotransferase?

Accepted Answer

A) isomerase 
B) uricase 
C) protease 
D) kinase 
A) isomerase 
B) uricase 
C) protease 
D) kinase

Question 16

In the reaction mechanism below,which components are competitive for binding to free enzyme E?

Accepted Answer

A) P and A 
B) A and B 
C) B and Q 
D) Q and A 
A) P and A 
B) A and B 
C) B and Q 
D) Q and A

Question 17

Which of these antibiotics acts by forming a covalent derivative of the enzyme glycoprotein peptidase?

Accepted Answer

A) antimycin 
B) neomycin 
C) oligomycin 
D) penicillin 
A) antimycin 
B) neomycin 
C) oligomycin 
D) penicillin

Question 18

Which of the following is NOT a characteristic of ribozymes?

Accepted Answer

A) They emerge from the reaction changed. 
B) They are substrate specific. 
C) They enhance the reaction rate. 
D) They are RNA molecules. 
A) They emerge from the reaction changed. 
B) They are substrate specific. 
C) They enhance the reaction rate. 
D) They are RNA molecules.

Question 19

Which reaction would NOT proceed via bimolecular elementary steps?

Accepted Answer

A) C + D→ T + U 
B) a reaction with a rate constant in the units of s-1 
C) 2A →D + E 
D) a reaction with a molecularity of 2 
A) C + D→ T + U 
B) a reaction with a rate constant in the units of s-1 
C) 2A →D + E 
D) a reaction with a molecularity of 2

Question 20

Which of the following is NOT correct regarding the transition state of a reaction?

Accepted Answer

A) The transition state is located at the height of a free energy diagram. 
B) The transition state,once reached,indicates that there is a high probability that the reaction will occur. 
C) The energy required to raise the average energy of one mole of reactant to the transition state is the free energy of activation. 
D) The transition state energy level is the sum of the energy levels of the reactants and products. 
A) The transition state is located at the height of a free energy diagram. 
B) The transition state,once reached,indicates that there is a high probability that the reaction will occur. 
C) The energy required to raise the average energy of one mole of reactant to the transition state is the free energy of activation. 
D) The transition state energy level is the sum of the energy levels of the reactants and products.

Exam 12: Enzymes Kinetics and Specificity

Which of the following is NOT correct regarding non-competitive inhibition?

Against which type of antigen is a catalytic antibody (abzyme)generated?

What is the definition of the free energy of activation,∆G‡?

For an enzyme-catalyzed reaction,the initial velocity was determined at 2 different concentrations of the substrate.Which of the following would be closest to the value of Vmₐₓ?

Which of the following is a feature of uncompetitive inhibition?

Which of the following is NOT correct regarding enzyme pathways?

A plot of 1/V versus 1/[S] for an enzyme-catalyzed reaction gave a line with an equation of y = 0.5x + 0.2.The same enzyme with an inhibitor present gave a line with an equation of y = 1.1x + 0.2.Which of these statements is correct regarding the inhibition?

Which term defines the catalytically active complex of an apoenzyme and its prosthetic group?

Which of the following is correct regarding the Michaelis-Menten constant,Km,for this kinetic mechanism?

In the enzyme catalyzed reaction sequence below,can the E-PO₄- intermediate be predicted and why?

Which of the following is NOT a distinctive feature of enzymes?

What is the basis for the International Units of an enzyme?

Which of the following is NOT correct for catalysts?

If an enzyme has a Vmₐₓ of 15 mM/min,what is the velocity if the substrate is present at ¼ of the Km?

What term describes an enzyme that is an ATP-dependent phosphotransferase?

In the reaction mechanism below,which components are competitive for binding to free enzyme E?

Which of these antibiotics acts by forming a covalent derivative of the enzyme glycoprotein peptidase?

Which of the following is NOT a characteristic of ribozymes?

Which reaction would NOT proceed via bimolecular elementary steps?

Which of the following is NOT correct regarding the transition state of a reaction?

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Lipid Biosynthesis

Membranes and Membrane Transport

The Reception and Transmission of Extracellular Information

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Nutrition and the Organization of Metabolism

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Nitrogen Acquisition and Amino Acid Metabolism

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Synthesis and Degradation of Nucleotides

Recombinant Dna: Cloning and Creation of Chimeric Genes

DNA Metabolism: Replication, recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Post-Transcriptional Regulation of Gene Expression

Completing the Protein Life Cycle: Folding, processing, and Degradation

Metabolic Integration and Organ Specialization

Filters

A plot of 1/V versus 1/[S] for an enzyme-catalyzed reaction gave a line with an equation of y = 0.5x + 0.2.The same enzyme with an inhibitor present gave a line with an equation of y = 1.1_x + 0.2.Which of these statements is correct regarding the inhibition?

If an enzyme has a Vmₐₓ of 15 mM/min,what is the velocity if the substrate is present at ¼ of the K_m?