Question 1

The pancreatic enzymes trypsin, chymotrypsin, and elastase all hydrolyze peptide bonds on the carbonyl side of several different amino acids in a protein.What term best describes their enzyme specificity?

Accepted Answer

A)  stereospecific
B)  peptide
C)  absolute
D)  linkage
E)  group

Question 2

Isomerases rearrange the functional groups within a molecule.

Accepted Answer

A) True 
 B)False

Question 3

Elastase is a protease enzyme that cleaves peptide bonds on the carbonyl side of the amino acids glycine and alanine.What products result from treatment of a peptide with the primary structure shown below with elastase? Pro-Gly-Phe-Ala

Accepted Answer

A)  the individual amino acids proline, glycine, phenylalanine, and alanine
B)  Pro-Gly, phenylalanine, and alanine
C)  proline, Gly-Phe, and alanine
D)  Pro-Gly, and Phe-Ala
E)  proline, glycine, and Phe-Ala

Question 4

What is the water-soluble vitamin from which NAD+ is made?

Accepted Answer

A)  riboflavin (B2) 
B)  niacin (B3) 
C)  pyridoxine (B6) 
D)  cyanocobalamine (B12) 
E)  riboflavin (B2)  and niacin (B3)  are correct.

Question 5

A proenzyme is an inactive form of an enzyme.

Accepted Answer

A) True 
 B)False

Question 6

Many enzymes are destroyed if the temperature rises significantly above 37ºC.

Accepted Answer

A) True 
 B)False

Question 7

A holoenzyme is a functional enzyme composed of what two parts?

Accepted Answer

A)  apoenzyme and cofactor
B)  amino acid and NAD+
C)  substrate and catalyst
D)  transferase and ligase
E)  substrate and inhibitor

Question 8

The enzyme hexokinase catalyzes the phosphorylation of glucose according to the reaction shown below.Glucosamine is a competitive inhibitor of hexokinase.Which of the following best describes the inhibition by glucosamine?

Accepted Answer

A)  Glucosamine stabilizes the active site of the enzyme, preventing glucose-6-phosphate from being released.
B)  Glucosamine reacts with glucose, preventing it from binding to the active site of the enzyme.
C)  Glucosamine binds to the active site of the enzyme, preventing glucose from binding.
D)  Glucosamine binds to the surface of the enzyme, causing a change in the shape of both the enzyme and the active site, preventing glucose from binding.
E)  Glucosamine reacts with glucose-6-phosphate, preventing it from being released from the active site.

Question 9

The graph shows how the rate of an enzyme-catalyzed reaction depends on the variable x.Which of the following quantities could x most likely represent?

Accepted Answer

A)  enzyme concentration
B)  energy
C)  temperature
D)  substrate concentration
E)  progress of reaction

Question 10

The penicillin class of antibiotics is inhibitors of an enzyme responsible for the formation of bacterial cell walls.The penicillin covalently binds to a serine residue in the active site of the enzyme, as depicted below.What type of bond is formed between the penicillin and the active site?

Accepted Answer

A)  hydrogen bond
B)  ionic bond
C)  glycosidic linkage
D)  ester bond
E)  acetal bond

Question 11

The graph shows how the rate of an enzyme-catalyzed reaction depends on the variable x.Which of the following quantities could x most likely represent?

Accepted Answer

A)  temperature
B)  pH
C)  energy
D)  substrate concentration
E)  progress of reaction

Question 12

What type of specificity is displayed by an enzyme that is able to catalyze a reaction of D-glucose, but not L-glucose?

Accepted Answer

A)  absolute specificity
B)  stereospecificity
C)  group specificity
D)  optical specificity
E)  sugar specificity

Question 13

Which statement concerning an enzyme is true?

Accepted Answer

A)  An enzyme increases the size of the equilibrium constant of the reaction it catalyzes.
B)  An enzyme decreases the size of the equilibrium constant of the reaction it catalyzes.
C)  An enzyme shifts the equilibrium so that more product is formed when equilibrium is reached.
D)  An enzyme increases the rate of a chemical reaction by lowering the activation energy.
E)  An enzyme slows down reactions that occur too rapidly to be effective in the body.

Question 14

The presence of an enzyme will alter the relative ratio of product to reactant for a biochemical reaction.

Accepted Answer

A) True 
 B)False

Question 15

What is the first step in an enzyme-catalyzed reaction?

Accepted Answer

A)  catalysis of enzyme
B)  dimerizing the substrate
C)  ionization of enzyme
D)  decrease of pH
E)  formation of an enzyme-substrate complex

Question 16

About half of the 223 amino acids in the enzyme trypsin are hydrophobic. Where in the tertiary structure of this globular protein are these amino acids most likely to be found?

Accepted Answer

A)  at the N-terminal end of the protein chain
B)  at the C-terminal end of the protein chain
C)  on the exterior surface of the folded protein
D)  in the interior of the folded protein
E)  in the active site of the enzyme

Question 17

For enzyme-catalyzed reactions, what happens as the concentration of the substrate is increased?

Accepted Answer

A)  The rate continues to increase as substrate concentration increases.
B)  The rate increases until it reaches a maximum, constant value.
C)  The rate increases until it reaches a maximum, then the rate decreases.
D)  The rate decreases with increasing concentration of the substrate.
E)  The rate decreases until it reaches a minimum, constant value.

Question 18

Proteases, or proteolytic enzymes, are responsible for which of the following functions?

Accepted Answer

A)  formation of the zwitterion form of a protein
B)  hydrolysis of the ester bonds in dietary triglycerides
C)  hydrolysis of the peptide bonds between amino acids in proteins
D)  formation of the glycosidic linkages in disaccharides and polysaccharides
E)  formation of bacterial cell walls

Question 19

The protease enzyme chymotrypsin cleaves peptide bonds on the carbonyl side of aromatic amino acids.Which labeled bond in the peptide below would be cleaved by chymotrypsin?

Accepted Answer

A)  A
B)  B
C)  C
D)  D
E)  E

Question 20

Proteolytic digestive enzymes are often produced in an inactive form.What is the name that refers to the inactive form of an enzyme?

Accepted Answer

A)  isozyme
B)  zwitterion
C)  proenzyme
D)  inhibitor
E)  allele

Exam 19: Enzymes

Many enzymes are destroyed if the temperature rises significantly above 37ºC.

Correct AnswerverifiedShow Answer

For enzyme-catalyzed reactions, what happens as the concentration of the substrate is increased?

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About half of the 223 amino acids in the enzyme trypsin are hydrophobic. Where in the tertiary structure of this globular protein are these amino acids most likely to be found?

Correct AnswerverifiedShow Answer

The penicillin class of antibiotics is inhibitors of an enzyme responsible for the formation of bacterial cell walls.The penicillin covalently binds to a serine residue in the active site of the enzyme, as depicted below.What type of bond is formed between the penicillin and the active site?

Correct AnswerverifiedShow Answer

Proteolytic digestive enzymes are often produced in an inactive form.What is the name that refers to the inactive form of an enzyme?

Correct AnswerverifiedShow Answer

The pancreatic enzymes trypsin, chymotrypsin, and elastase all hydrolyze peptide bonds on the carbonyl side of several different amino acids in a protein.What term best describes their enzyme specificity?

Correct AnswerverifiedShow Answer

The graph shows how the rate of an enzyme-catalyzed reaction depends on the variable x.Which of the following quantities could x most likely represent?

Correct AnswerverifiedShow Answer

Isomerases rearrange the functional groups within a molecule.

Correct AnswerverifiedShow Answer

What is the water-soluble vitamin from which NAD+ is made?

Correct AnswerverifiedShow Answer

The presence of an enzyme will alter the relative ratio of product to reactant for a biochemical reaction.

Correct AnswerverifiedShow Answer

The protease enzyme chymotrypsin cleaves peptide bonds on the carbonyl side of aromatic amino acids.Which labeled bond in the peptide below would be cleaved by chymotrypsin?

Correct AnswerverifiedShow Answer

Which statement concerning an enzyme is true?

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What is the first step in an enzyme-catalyzed reaction?

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A proenzyme is an inactive form of an enzyme.

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What type of specificity is displayed by an enzyme that is able to catalyze a reaction of D-glucose, but not L-glucose?

Correct AnswerverifiedShow Answer

Proteases, or proteolytic enzymes, are responsible for which of the following functions?

Correct AnswerverifiedShow Answer

The enzyme hexokinase catalyzes the phosphorylation of glucose according to the reaction shown below.Glucosamine is a competitive inhibitor of hexokinase.Which of the following best describes the inhibition by glucosamine?

Correct AnswerverifiedShow Answer

Elastase is a protease enzyme that cleaves peptide bonds on the carbonyl side of the amino acids glycine and alanine.What products result from treatment of a peptide with the primary structure shown below with elastase? Pro-Gly-Phe-Ala

Correct AnswerverifiedShow Answer

A holoenzyme is a functional enzyme composed of what two parts?

Correct AnswerverifiedShow Answer

The graph shows how the rate of an enzyme-catalyzed reaction depends on the variable x.Which of the following quantities could x most likely represent?

Correct AnswerverifiedShow Answer

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What is the water-soluble vitamin from which NAD⁺ is made?

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