Question 1

Which of the following best describes negative cooperativity?

Accepted Answer

A)   Binding of one substrate molecule prevents the enzyme from working at all.
B)   Binding of one substrate molecule inhibits the binding of a second substrate.
C)   Binding of one substrate molecule enhances the binding of a second substrate.
D)   Binding of one substrate molecule inhibits the binding of other effectors.E) A) and D)
F) A) and B)

Question 2

The pH profile of an enzyme can help identify specific amino acids in the active site because:

Accepted Answer

A)   all enzymes have a pH optimum
B)   only the active site amino acids can detect changes in pH
C)   acidic and basic amino acids are often involved in the active site and pH changes can change their ability to catalyze a reaction
D)   the pH optimum is always the pI of the most critical amino acid in the active siteE) A) and D)
F) A) and C)

Question 3

An important step in elucidating the behavior of an enzyme is

Accepted Answer

A)   obtaining a crystalline sample of the enzyme.
B)   insuring that metal ions are always excluded from the enzyme sample.
C)   determining the active site residues.
D)   none of theseE) A) and B)
F) A) and C)

Question 4

The main distinguishing feature of the concerted model for the behavior of allosteric enzymes is that

Accepted Answer

A)   the conformation of all subunits changes simultaneously.
B)   it applies only to dimeric enzymes.
C)   it involves three possible conformations for all subunits.
D)   the T and R conformations exist in roughly equal amounts.E) A) and D)
F) B) and C)

Question 5

Exhibit 7A 	ext { Exhibit 7A } Exhibit 7A

-Refer to Exhibit 7A. Which two enzymes would be the most likely ones to regulate if this pathway is freely reversible and can go both ways?

Accepted Answer

A)   1 and 2
B)   1 and 3
C)   1 and 5
D)   2 and 4
E)   4 and 5 F) A) and D)
G) A) and C)

Question 6

Which of the following statements about coenzymes is true?

Accepted Answer

A)   They are commonly derived from vitamins.
B)   They bind to the active site region on specific types of enzymes.
C)   They can be metal ions, such as Zn(II) .
D)   NAD+, FAD and biotin are all examples of coenzymes.
E)   All of these statements are true.F) A) and D)
G) A) and B)

Question 7

ATP is a negative allosteric effector for glycogen phosporylase. This is an example of

Accepted Answer

A)   feedback inhibition.
B)   positive cooperativity.
C)   negative cooperativity.
D)   competitive inhibition.E) A) and B)
F) None of the above

Question 8

A velocity curve (V vs. [S])  for a typical allosteric enzyme will be

Accepted Answer

A)   a rectangular hyperbola.
B)   a sigmoid curve.
C)   a straight line.
D)   a parabola.
E)   none of theseF) B) and E)
G) A) and C)

Question 9

According to the concerted model of allosteric behavior, an allosteric activator

Accepted Answer

A)   favors the taut (tight)  form of the enzyme.
B)   favors the relaxed form of the enzyme.
C)   can only bind to the enzyme if the substrate is already bound.
D)   can only bind to the enzyme if the substrate has not already bound.E) C) and D)
F) A) and B)

Question 10

Is the Michaelis-Menten equation useful when studying allosteric enzymes?

Accepted Answer

A)   Yes
B)   No
C)   Only if the enzyme displays positive cooperativity.
D)   Only if the enzyme displays negative cooperativity.E) A) and C)
F) A) and D)

Question 11

The term K0.5 is analogous to the KM

Accepted Answer

A) True 
 B)False

Question 12

Important mechanisms of enzymatic catalysis include

Accepted Answer

A)   nucleophilic reactions
B)   general acid-base catalysis
C)   Lewis acid-base catalysis
D)   all of theseE) B) and D)
F) C) and D)

Question 13

Exhibit 7A 	ext { Exhibit 7A } Exhibit 7A

-Refer to Exhibit 7A. The final product, R, will most likely inhibit which reaction?

Accepted Answer

A)   1
B)   2
C)   3
D)   4
E)   5 F) A) and E)
G) B) and E)

Question 14

Redox reactions often use this cofactor:

Accepted Answer

A)   Riboflavin
B)   Lipoic acid
C)   Pyridoxal
D)   Thiamine
E)   BiotinF) A) and E)
G) None of the above

Question 15

Enzymes that catalyze similar functions will invariably have

Accepted Answer

A)   similar overall structures.
B)   serine in their active sites.
C)   histidine in their active sites.
D)   active sites that can catalyze the reactions in question.E) All of the above
F) None of the above

Question 16

Which groups of amino acids are most likely to be found in the active site of an enzyme?

Accepted Answer

A)   leucine, lysine, alanine.
B)   cysteine, isoleucine, phenylalanine.
C)   tyrosine, threonine, leucine.
D)   serine, histidine, aspartate.E) A) and D)
F) None of the above

Question 17

Homotrophic effects for allosteric enzymes involve

Accepted Answer

A)   the same molecule binding to different sites in the enzyme.
B)   different molecules binding to the same site in an enzyme.
C)   different molecules binding to different sites in the same enzyme.
D)   All of these are homotrophic effects.E) A) and C)
F) A) and B)

Question 18

Where do allosteric inhibitors bind on an enzyme?

Accepted Answer

A)   They always bind at a site different from the active site.
B)   They always bind at the active site.
C)   They can bind at either active site or another site.
D)   They always bind directly to the substrate
E)   none of theseF) A) and D)
G) A) and C)

Question 19

Which of the following types of amino acids in an active site is least likely to be involved in enzyme catalysis?

Accepted Answer

A)   Those with hydrophilic, neutral side-chains.
B)   Those with negatively charged side-chains.
C)   Those with positively charge side-chains.
D)   Those with hydrocarbon side-chains.E) B) and C)
F) A) and B)

Question 20

Metal ions play an important role in reaction mechanisms because

Accepted Answer

A)   they block the active site of enzymes so that inhibitors cannot bind.
B)   they can act as Lewis acids.
C)   water is excluded from the active site when metal ions are bound.
D)   they prevent protein aggregation.E) A) and D)
F) B) and D)

Exam 7: The Behavior of Proteins: Enzymes, Mechanisms, and Control

Metal ions play an important role in reaction mechanisms because

Correct Answer
verified

According to the concerted model of allosteric behavior, an allosteric activator

Correct Answer
verified

An important step in elucidating the behavior of an enzyme is

Correct Answer
verified

A velocity curve (V vs. [S]) for a typical allosteric enzyme will be

Correct Answer
verified

Homotrophic effects for allosteric enzymes involve

Correct Answer
verified

Correct Answer
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Which groups of amino acids are most likely to be found in the active site of an enzyme?

Correct Answer
verified

$\text { Exhibit 7A }$ $\text { Exhibit 7A } -Refer to Exhibit 7A. The final product, R, will most likely inhibit which reaction? A) 1 B) 2 C) 3 D) 4 E) 5$ -Refer to Exhibit 7A. The final product, R, will most likely inhibit which reaction?

Correct Answer
verified

Which of the following types of amino acids in an active site is least likely to be involved in enzyme catalysis?

Correct Answer
verified

ATP is a negative allosteric effector for glycogen phosporylase. This is an example of

Correct Answer
verified

The pH profile of an enzyme can help identify specific amino acids in the active site because:

Correct Answer
verified

Redox reactions often use this cofactor:

Correct Answer
verified

Important mechanisms of enzymatic catalysis include

Correct Answer
verified

Which of the following best describes negative cooperativity?

Correct Answer
verified

Which of the following statements about coenzymes is true?

Correct Answer
verified

Enzymes that catalyze similar functions will invariably have

Correct Answer
verified

The main distinguishing feature of the concerted model for the behavior of allosteric enzymes is that

Correct Answer
verified

The term K_0.5 is analogous to the K_M

Correct Answer
verified

Where do allosteric inhibitors bind on an enzyme?

Correct Answer
verified

Is the Michaelis-Menten equation useful when studying allosteric enzymes?

Correct Answer
verified

Exam 7: The Behavior of Proteins: Enzymes, Mechanisms, and Control

Metal ions play an important role in reaction mechanisms because

Correct AnswerverifiedShow Answer

According to the concerted model of allosteric behavior, an allosteric activator

Correct AnswerverifiedShow Answer

An important step in elucidating the behavior of an enzyme is

Correct AnswerverifiedShow Answer

A velocity curve (V vs. [S]) for a typical allosteric enzyme will be

Correct AnswerverifiedShow Answer

Homotrophic effects for allosteric enzymes involve

Correct AnswerverifiedShow Answer

Exhibit 7A \text { Exhibit 7A } Exhibit 7A -Refer to Exhibit 7A. Which two enzymes would be the most likely ones to regulate if this pathway is freely reversible and can go both ways?

Correct AnswerverifiedShow Answer

Which groups of amino acids are most likely to be found in the active site of an enzyme?

Correct AnswerverifiedShow Answer

Exhibit 7A \text { Exhibit 7A } Exhibit 7A -Refer to Exhibit 7A. The final product, R, will most likely inhibit which reaction?

Correct AnswerverifiedShow Answer

Which of the following types of amino acids in an active site is least likely to be involved in enzyme catalysis?

Correct AnswerverifiedShow Answer

ATP is a negative allosteric effector for glycogen phosporylase. This is an example of

Correct AnswerverifiedShow Answer

The pH profile of an enzyme can help identify specific amino acids in the active site because:

Correct AnswerverifiedShow Answer

Redox reactions often use this cofactor:

Correct AnswerverifiedShow Answer

Important mechanisms of enzymatic catalysis include

Correct AnswerverifiedShow Answer

Which of the following best describes negative cooperativity?

Correct AnswerverifiedShow Answer

Which of the following statements about coenzymes is true?

Correct AnswerverifiedShow Answer

Enzymes that catalyze similar functions will invariably have

Correct AnswerverifiedShow Answer

The main distinguishing feature of the concerted model for the behavior of allosteric enzymes is that

Correct AnswerverifiedShow Answer

The term K0.5 is analogous to the KM

Correct AnswerverifiedShow Answer

Where do allosteric inhibitors bind on an enzyme?

Correct AnswerverifiedShow Answer

Is the Michaelis-Menten equation useful when studying allosteric enzymes?

Correct AnswerverifiedShow Answer

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$\text { Exhibit 7A }$ $\text { Exhibit 7A } -Refer to Exhibit 7A. The final product, R, will most likely inhibit which reaction? A) 1 B) 2 C) 3 D) 4 E) 5$ -Refer to Exhibit 7A. The final product, R, will most likely inhibit which reaction?

Correct Answer
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The term K_0.5 is analogous to the K_M

Correct Answer
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Correct Answer
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