Question 1

In the Lineweaver-Burk plot of an enzyme reaction,the Km is given by the ________.

Accepted Answer

A) x-intercept 
B) y-intercept 
C) negative reciprocal of the x-intercept 
D) reciprocal of the y-intercept 
A) x-intercept 
B) y-intercept 
C) negative reciprocal of the x-intercept 
D) reciprocal of the y-intercept

Question 2

Which might be a method used for distinguishing among several mechanistic possibilities in a multi-substrate reaction?

Accepted Answer

A) Measure Km in the presence of one substrate at a time. 
B) Measure the rate with respect to one substrate while varying the concentration of another substrate. 
C) Measure the rate while adding inactivators for all but one substrate. 
D) Any of the above. 
A) Measure Km in the presence of one substrate at a time. 
B) Measure the rate with respect to one substrate while varying the concentration of another substrate. 
C) Measure the rate while adding inactivators for all but one substrate. 
D) Any of the above.

Question 3

The "T" state refers to the ________.

Accepted Answer

A) inactive conformation of the enzyme 
B) transition state of the product 
C) form of the enzyme without the modulator bound at the regulatory site 
D) denatured form of the enzyme 
A) inactive conformation of the enzyme 
B) transition state of the product 
C) form of the enzyme without the modulator bound at the regulatory site 
D) denatured form of the enzyme

Question 4

It is difficult to determine either Km or Vmax from a graph of velocity vs.substrate concentration because

Accepted Answer

A) too much substrate is required to determine them. 
B) the graph is sigmoidal. 
C) an asymptotic value must be determined from the graph. 
D) the points on the graph are often not spread out on the hyperbola. 
A) too much substrate is required to determine them. 
B) the graph is sigmoidal. 
C) an asymptotic value must be determined from the graph. 
D) the points on the graph are often not spread out on the hyperbola.

Question 5

Which statement is true about the removal of reversible inhibitors from enzyme solutions?

Accepted Answer

A) PAGE is the primary technique used for this purpose. 
B) Dialysis and gel filtration are often used. 
C) These inhibitors cannot be separated from the enzyme without treatment with diisopropylfluorophosphate. 
D) Removal of reversible inhibitors is extremely difficult and can be achieved only after many purification steps. 
A) PAGE is the primary technique used for this purpose. 
B) Dialysis and gel filtration are often used. 
C) These inhibitors cannot be separated from the enzyme without treatment with diisopropylfluorophosphate. 
D) Removal of reversible inhibitors is extremely difficult and can be achieved only after many purification steps.

Question 6

Which statement is false about the sequential theory?

Accepted Answer

A) It treats the concerted theory as a limiting simple case. 
B) It allows for a distribution of high and low affinity subunits in the same protein. 
C) It assumes more than one conformation of a particular subunit can have high affinity for the ligand. 
D) It is also called the ligand-induced theory and is more general than the concerted theory. 
A) It treats the concerted theory as a limiting simple case. 
B) It allows for a distribution of high and low affinity subunits in the same protein. 
C) It assumes more than one conformation of a particular subunit can have high affinity for the ligand. 
D) It is also called the ligand-induced theory and is more general than the concerted theory.

Question 7

Affinity labels are radioactive competitive inhibitors used to identify the most important residues in an enzyme's active site.

Accepted Answer

A) True 
 B)False

Question 8

Increasing the concentration of a classic competitive inhibitor has no effect on the maximum velocity of an enzyme-substrate reaction.

Accepted Answer

A) True 
 B)False

Question 9

Which is appropriate for initial rate method experiments to analyze an enzyme-catalyzed reaction?

Accepted Answer

A) Substrate concentration is constant and the rate is measured at different concentrations of enzyme. 
B) Enzyme concentration is constant and the rate is measured at different substrate concentrations. 
C) The substrate and enzyme concentrations are varied inversely with respect to one another and the rate is measured. 
D) Both enzyme and substrate concentrations are constant.The temperature is varied and the rate is measured. 
E) All of the above. 
A) Substrate concentration is constant and the rate is measured at different concentrations of enzyme. 
B) Enzyme concentration is constant and the rate is measured at different substrate concentrations. 
C) The substrate and enzyme concentrations are varied inversely with respect to one another and the rate is measured. 
D) Both enzyme and substrate concentrations are constant.The temperature is varied and the rate is measured. 
E) All of the above.

Question 10

The main difference between chemical and enzyme kinetics is that

Accepted Answer

A) enzyme reactions are altered by pH. 
B) enzyme reactions depend on the concentration of the substrate. 
C) enzyme reactions depend on the concentration of the enzyme and its recycling. 
D) the rate constant for the formation of products is k2. 
A) enzyme reactions are altered by pH. 
B) enzyme reactions depend on the concentration of the substrate. 
C) enzyme reactions depend on the concentration of the enzyme and its recycling. 
D) the rate constant for the formation of products is k2.

Question 11

The ________ theory explains cooperative binding by suggesting all subunits of a given protein have the same conformation,either all R or all T.

Accepted Answer

A) concerted 
B) entropy-driven 
C) sequential 
D) simultaneous 
A) concerted 
B) entropy-driven 
C) sequential 
D) simultaneous

Question 12

When varying the substrate concentration at a fixed concentration of enzyme it is observed that at low concentrations of substrate the reaction is ________,while at high concentrations of substrate the reaction is ________.

Accepted Answer

A) maximal;initial 
B) initial;maximal 
C) second order;first order 
D) first order;second order 
E) first order;zero order 
A) maximal;initial 
B) initial;maximal 
C) second order;first order 
D) first order;second order 
E) first order;zero order

Question 13

Most of the known enzymes are ________.

Accepted Answer

A) oxidoreductases 
B) transferases 
C) hydrolases 
D) lyases 
E) isomerases 
A) oxidoreductases 
B) transferases 
C) hydrolases 
D) lyases 
E) isomerases

Question 14

The regulatory and active sites on an oligomeric enzyme can be on different subunits.

Accepted Answer

A) True 
 B)False

Question 15

The non-enzymatic hydrolysis of sucrose into glucose and fructose is an example of a pseudo first-order reaction because

Accepted Answer

A) no enzymes are involved. 
B) water has no role in the reaction. 
C) water is of such high concentration as to be considered constant. 
D) water is present at concentrations proportional to the sucrose. 
A) no enzymes are involved. 
B) water has no role in the reaction. 
C) water is of such high concentration as to be considered constant. 
D) water is present at concentrations proportional to the sucrose.

Question 16

In bi-substrate reactions the substrates always bind to the enzyme in a specific order.

Accepted Answer

A) True 
 B)False

Question 17

Select the correct class of enzyme for each of these reactions.
-L-Glutamate + ATP + NH₄+ → L-glutamine + ADP + Pi

Accepted Answer

A) oxidoreductase 
B) lyase 
C) isomerase 
D) transferase 
E) hydrolase
F)ligase 
A) oxidoreductase 
B) lyase 
C) isomerase 
D) transferase 
E) hydrolase
F)ligase

Question 18

Select the correct class of enzyme for each of these reactions.
-Pyruvate + H+ → Acetaldehyde + Carbon dioxide

Accepted Answer

A) oxidoreductase 
B) lyase 
C) isomerase 
D) transferase 
E) hydrolase
F)ligase 
A) oxidoreductase 
B) lyase 
C) isomerase 
D) transferase 
E) hydrolase
F)ligase

Question 19

What distinguishes reversible inhibitors from irreversible inhibitors?

Accepted Answer

A) Reversible inhibitors are not covalently bound to enzymes but irreversible inhibitors are. 
B) There is an equilibrium between bound and unbound reversible inhibitor.There usually is little back reaction for the binding of an irreversible inhibitor. 
C) Reversible inhibitors can often be retrieved (purified)from solutions of enzymes,but irreversible inhibitors will react with enzyme and no longer be retrievable in their original form. 
D) All of the above. 
E) A and B only. 
A) Reversible inhibitors are not covalently bound to enzymes but irreversible inhibitors are. 
B) There is an equilibrium between bound and unbound reversible inhibitor.There usually is little back reaction for the binding of an irreversible inhibitor. 
C) Reversible inhibitors can often be retrieved (purified)from solutions of enzymes,but irreversible inhibitors will react with enzyme and no longer be retrievable in their original form. 
D) All of the above. 
E) A and B only.

Question 20

What type of inhibition is indicated by the data graphed below?

Accepted Answer

A) Competitive. 
B) Uncompetitive. 
C) Noncompetitive. 
D) Irreversible. 
A) Competitive. 
B) Uncompetitive. 
C) Noncompetitive. 
D) Irreversible.

Exam 5: Properties of Enzymes

In the Lineweaver-Burk plot of an enzyme reaction,the Km is given by the ________.

Which might be a method used for distinguishing among several mechanistic possibilities in a multi-substrate reaction?

The "T" state refers to the ________.

It is difficult to determine either Km or Vmax from a graph of velocity vs.substrate concentration because

Which statement is true about the removal of reversible inhibitors from enzyme solutions?

Which statement is false about the sequential theory?

Affinity labels are radioactive competitive inhibitors used to identify the most important residues in an enzyme's active site.

Increasing the concentration of a classic competitive inhibitor has no effect on the maximum velocity of an enzyme-substrate reaction.

Which is appropriate for initial rate method experiments to analyze an enzyme-catalyzed reaction?

The main difference between chemical and enzyme kinetics is that

The ________ theory explains cooperative binding by suggesting all subunits of a given protein have the same conformation,either all R or all T.

When varying the substrate concentration at a fixed concentration of enzyme it is observed that at low concentrations of substrate the reaction is ________,while at high concentrations of substrate the reaction is ________.

Most of the known enzymes are ________.

The regulatory and active sites on an oligomeric enzyme can be on different subunits.

The non-enzymatic hydrolysis of sucrose into glucose and fructose is an example of a pseudo first-order reaction because

In bi-substrate reactions the substrates always bind to the enzyme in a specific order.

Select the correct class of enzyme for each of these reactions. -L-Glutamate + ATP + NH₄+ → L-glutamine + ADP + Pi

Select the correct class of enzyme for each of these reactions. -Pyruvate + H+ → Acetaldehyde + Carbon dioxide

What distinguishes reversible inhibitors from irreversible inhibitors?

What type of inhibition is indicated by the data graphed below?

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Atp Synthesis

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

DNA Replication, repair, and Recombination

Transcription and RNA Processing

Protein Synthesis

Filters

When varying the substrate concentration at a fixed concentration of enzyme it is observed that at low concentrations of substrate the reaction is ,while at high concentrations of substrate the reaction is .