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Chem 221 - Biochemistry for Science Majors » Fall 2021 » L10 Enzymes Part 3 of 3

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Question #1

In the double reciprocal plot, in presence of a competitive inhibitor, the X intercept is further from the origin.

A. FALSE

B. TRUE

Question #2

In uncompetitive inhibition, If Km decrease, the ratio 1/Km will increase, it will become larger in the negative direction, and the X intercept is will further to the left.

A. TRUE

B. FALSE

Question #3

Which one of the following statements is true?

A. competitive inhibition is irreversible and cannot be overcome by increasing the concentration of the substrate

B. competitive inhibition is reversible and cannot be overcome by increasing the concentration of the substrate

C. non-competitive inhibition is normally irreversible but can be overcome by increasing the concentration of the substrate

D. competitive inhibition is reversible and can be overcome by increasing the concentration of the substrate

Question #4

In competitive inhibition, an inhibitor:

A. binds covalently to the enzyme.

B. binds reversibly at the active site.

C. lowers the characteristic Vmax of the enzyme.

D. binds only to the ES complex.

E. binds at several different sites on an enzyme.

Question #5

A small molecule that decreases the activity of an enzyme by binding to a site other than the catalytic site is termed a(n):

A. stereospecific agent

B. alternative inhibitor

C. transition-state analog

D. competitive inhibitor

E. allosteric inhibitor

Question #6

Which of the following statements about competitive inhibition of an enzyme-catalyzed reaction is correct?

A. The Vmax of a reaction decreases in the presence of a competitive inhibitor.

B. A competitive inhibitor can bind to the enzyme-substrate complex.

C. Competitive inhibition can be overcome by the addition of large amounts of substrate to a reaction.

D. The addition of large amounts of substrate to a reaction cannot overcome the effect of a competitive inhibitor.

Question #7

Choose the false statement:

A. Competitive inhibition is a form of enzyme inhibition where binding of the inhibitor to the active site on the enzyme prevents binding of the substrate

B. Due its resemblance to the substrate, a competitive inhibitor binds to the same site the substrate binds to

C. In competitive inhibition, KM decreases

D. The competitive inhibitor has a chemical structure that resembles the one of the substrate

Question #8

Choose the TRUE statement:

A. In competitive inhibition the slope decreases.

B. In competitive inhibition the Y intercept is less negative (it’s closer to the origin)

C. In competitive inhibition the X intercept is less negative (it’s closer to the origin)

Question #9

Noncompetitive inhibitors bind to the enzyme regardless whether the substrate is or isn’t bound into the active site.

A. FALSE

B. TRUE

Question #10

Increasing the substrate concentration can remove the effect of a competitive inhibitor.

A. FALSE

B. TRUE

Question #11

In noncompetitive inhibition, when the substrate binds to the active site of the enzyme, this binding creates a conformational change that creates a new pocket in the enzyme that can now bind to an inhibitor molecule.

A. FALSE

B. TRUE

Question #12

Often, the affinity of the inhibitor for the active site is lower than the affinity of the substrate for that active site.

A. TRUE

B. FALSE

Question #13

The presence of an uncompetitive inhibitor enhances the binding of the substrate to the enzyme and increases its Vmax.

A. FALSE

B. TRUE

Question #14

Choose the true statement:

A. In competitive inhibition the Y intercept is less negative (it’s closer to the origin)

B. In competitive inhibition the slope increases.

C. In uncompetitive inhibition the X intercept is less negative (it’s closer to the origin)

Question #15

An irreversible inhibitor dissociate very slowly from its target enzyme.

A. FALSE

B. TRUE

Question #16

The binding of a irreversible inhibitor is always covalent.

A. FALSE

B. TRUE

Question #17

In the double reciprocal plot, in presence of a competitive inhibitor, the slope is the same.

A. FALSE

B. TRUE

Question #18

The defining property of reversible inhibition is the ease with which the inhibitors can dissociate from the enzyme under certain conditions.

A. TRUE

B. FALSE

Question #19

The chemical structure of a competitive inhibitor resembles the structure of the substrate.

A. TRUE

B. FALSE

Question #20

In uncompetitive inhibition, when the substrate binds to the active site of the enzyme, this binding creates conformational changes that create a brand new pocket (allosteric site), where the inhibitor can now bind.

A. TRUE

B. FALSE

Question #21

The chemical structure of a competitive inhibitor must be identical to the structure of the substrate in order to bind to the active site.

A. TRUE

B. FALSE

Question #22

In competitive inhibition, Vmax stays the same, Km increases and the slope decreases.

A. FALSE

B. TRUE

Question #23

Increasing the substrate concentration can remove the effect of competitive inhibitor.

A. FALSE

B. TRUE

Question #24

In the presence of a competitive inhibitor, the substrate concentration has to be lower to reach half of the maximum velocity.

A. FALSE

B. TRUE

Question #25

In the double reciprocal plot, in presence of a competitive inhibitor, the Y intercept is the same.

A. FALSE

B. TRUE

Question #26

In the the double reciprocal plot of a competitive inhibitor both curves intersect the Y axis at the same value, at the same point.

A. TRUE

B. FALSE

Question #27

A noncompetitive inhibitor binds to the enzyme away from the active site, altering the shape of the enzyme so that even if the substrate can bind, the active site functions less effectively.

A. TRUE

B. FALSE

Question #28

An uncompetitive inhibitor binds only to the enzyme-substrate complex and locks the substrate in the enzyme, preventing its release.

A. TRUE

B. FALSE

Question #29

In uncompetitive inhibition, Vmax decreases, Km increases and the slope decreases.

A. TRUE

B. FALSE

Question #30

In uncompetitive inhibition, the inhibitor binds to an already existing allosteric site.

A. TRUE

B. FALSE

Question #31

In the presence of a uncompetitive inhibitor, the formation of the allosteric site only forms when the enzyme and the substrate have already interacted amongst themselves.

A. TRUE

B. FALSE

Question #32

Uncompetitive inhibition is overcome by adding substrate.

A. TRUE

B. FALSE

Question #33

An uncompetitive inhibitor is most effective at low substrate concentration.

A. FALSE

B. TRUE

Question #34

In the double reciprocal plot of an uncompetitive inhibition the Y intercept decreases.

A. FALSE

B. TRUE

Question #35

In uncompetitive inhibition Vmax decreases and 1/Vmax increases.

A. TRUE

B. FALSE

Question #36

In uncompetitive inhibition, KM increases and 1/KM decreases.

A. TRUE

B. FALSE

Question #37

A. TRUE

B. FALSE

Question #38

In noncompetitive inhibition, Vmax decreases, Km stays the same and the slope increases.

A. FALSE

B. TRUE

Question #39

Regarding NONCOMPETITIVE inhibition: What is the relationship between Km without the inhibitor and Km with the inhibitor?

A. Km without inhibitor > Km with inhibitor

B. Km without inhibitor = Km with inhibitor

C. Km without inhibitor < Km with inhibitor

Question #40

Which of the following statements about COMPETITIVE inhibition of an enzyme-catalyzed reaction is CORRECT?

A. The addition of large amounts of substrate to a reaction cannot overcome the effect of a competitive inhibitor

B. The Vmax of a reaction decreases in the presence of a competitive inhibitor

C. A competitive inhibitor can bind to the enzyme-substrate complex

D. Competitive inhibition can be overcome by the addition of large amounts of substrate to a reaction

Question #41

The Lineweaver-Burk plot is useful when determining the type of inhibition that an enzyme is experiencing because the Vmax and Km can be compared without estimation.

A. TRUE

B. FALSE

Question #42

The presence of a uncompetitive inhibitor lowers the affinity of the enzyme for its substrate.

A. TRUE

B. FALSE

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