Question 1

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

Accepted Answer

A) True 
 B)False

Question 2

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 3

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 4

The Lineweaver-Burk plot and other linear transformation of the Michaelis-Menten curve of kinetics are valuable for

Accepted Answer

A)  determination of Km. 
B)  determination of Vmax. 
C)  determination of kcat. 
D)  determination of types of enzyme inhibition. 
E)  All of the above 
A)  determination of Km. 
B)  determination of Vmax. 
C)  determination of kcat. 
D)  determination of types of enzyme inhibition. 
E)  All of the above

Question 5

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

Accepted Answer

A) True 
 B)False

Question 6

Which statement is false about regulatory enzymes that are controlled allosterically?

Accepted Answer

A)  They are always less active when a modulator is bound to them. 
B)  They are often larger than other enzymes. 
C)  They have more than one binding site. 
D)  They often catalyze the first step in a reaction pathway. 
A)  They are always less active when a modulator is bound to them. 
B)  They are often larger than other enzymes. 
C)  They have more than one binding site. 
D)  They often catalyze the first step in a reaction pathway.

Question 7

Two substances are used to produce a certain biological product in an enzyme-catalyzed reaction. It is found that both substrates must bind to the enzyme, first one, then the other before the product is produced. This is an example of a/an .

Accepted Answer

A)  linear reaction 
B)  ordered sequential reaction 
C)  random sequential reaction 
D)  ping-pong reaction 
A)  linear reaction 
B)  ordered sequential reaction 
C)  random sequential reaction 
D)  ping-pong reaction

Question 8

The catalytic proficiency of an enzyme is the .

Accepted Answer

A)  turnover number 
B)  Km/[E] 
C)  rate constant with the enzyme divided by the rate constant without the enzyme 
D)  rate constant with the enzyme times the rate constant without the enzyme 
A)  turnover number 
B)  Km/[E] 
C)  rate constant with the enzyme divided by the rate constant without the enzyme 
D)  rate constant with the enzyme times the rate constant without the enzyme

Question 9

Allosteric modulators bind covalently to the regulatory site of an enzyme and change its conformation.

Accepted Answer

A) True 
 B)False

Question 10

The assumptions made in calculating the Michaelis-Menten Equation include

Accepted Answer

A)  that the formation and decomposition of ES is the same for a period of time. 
B)  that the concentration of the substrate is much greater than the concentration of E. 
C)  that the value of k-2 can be ignored. 
D)  A, B and C 
E)  A and B only 
A)  that the formation and decomposition of ES is the same for a period of time. 
B)  that the concentration of the substrate is much greater than the concentration of E. 
C)  that the value of k-2 can be ignored. 
D)  A, B and C 
E)  A and B only

Question 11

An enzyme that catalyzes conversions of L-sugars to D-sugars is called a/an .

Accepted Answer

A)  lyase 
B)  hydrolase 
C)  synthetase 
D)  synthase 
E)  isomerase 
A)  lyase 
B)  hydrolase 
C)  synthetase 
D)  synthase 
E)  isomerase

Question 12

Which is not a reason for metabolite channeling?

Accepted Answer

A)  Protection of intermediates from degradation. 
B)  Increasing the overall rate of a reaction. 
C)  Producing locally high concentrations of intermediates. 
D)  Ensuring the enzyme is properly regulated. 
A)  Protection of intermediates from degradation. 
B)  Increasing the overall rate of a reaction. 
C)  Producing locally high concentrations of intermediates. 
D)  Ensuring the enzyme is properly regulated.

Question 13

In a ping-pong reaction which does not occur?

Accepted Answer

A)  One product is released before a second substrate is bound. 
B)  The enzyme covalently binds a portion of the first substrate. 
C)  The enzyme is permanently converted to an altered form by the first substrate. 
D)  A group is transferred from one substrate to another. 
A)  One product is released before a second substrate is bound. 
B)  The enzyme covalently binds a portion of the first substrate. 
C)  The enzyme is permanently converted to an altered form by the first substrate. 
D)  A group is transferred from one substrate to another.

Question 14

Natural inhibitors often are regulators of metabolic reactions.

Accepted Answer

A) True 
 B)False

Question 15

All irreversible inhibitors known are from man-made sources.

Accepted Answer

A) True 
 B)False

Question 16

Select the correct class of enzyme for each of these reactions. A) isomerase
B) ligase
C) lyase
D) transferase
E) oxidoreductase
F) hydrolase
-Lactate + NAD+ → Pyruvate +
NADH + H+

Accepted Answer

Question 17

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 18

Select the correct class of enzyme for each of these reactions. A) isomerase
B) ligase
C) lyase
D) transferase
E) oxidoreductase
F) hydrolase
-Pyruvate + H+ → Acetaldehyde + Carbon dioxide

Accepted Answer

Question 19

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 20

Select the correct class of enzyme for each of these reactions. A) isomerase
B) ligase
C) lyase
D) transferase
E) oxidoreductase
F) hydrolase
-Sucrose + H2O → Fructose +
Glucose

Accepted Answer

Exam 5: Properties of Enzymes

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

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

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

The Lineweaver-Burk plot and other linear transformation of the Michaelis-Menten curve of kinetics are valuable for

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

Which statement is false about regulatory enzymes that are controlled allosterically?

Two substances are used to produce a certain biological product in an enzyme-catalyzed reaction. It is found that both substrates must bind to the enzyme, first one, then the other before the product is produced. This is an example of a/an .

The catalytic proficiency of an enzyme is the .

Allosteric modulators bind covalently to the regulatory site of an enzyme and change its conformation.

The assumptions made in calculating the Michaelis-Menten Equation include

An enzyme that catalyzes conversions of L-sugars to D-sugars is called a/an .

Which is not a reason for metabolite channeling?

In a ping-pong reaction which does not occur?

Natural inhibitors often are regulators of metabolic reactions.

All irreversible inhibitors known are from man-made sources.

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Lactate + NAD+ → Pyruvate + NADH + H+

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

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Pyruvate + H+ → Acetaldehyde + Carbon dioxide

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

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Sucrose + H2O → Fructose + Glucose

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 Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

Filters

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Lactate + NAD⁺→ Pyruvate + NADH + H⁺

In the Lineweaver-Burk plot of an enzyme reaction, the K_mis given by the .

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Pyruvate + H⁺→ Acetaldehyde + Carbon dioxide

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Sucrose + H₂O → Fructose + Glucose