Question 1

Which of the following statements best describes the effect of a competitive inhibitor on enzyme kinetics?

Accepted Answer

It increases $$K_m$$ but does not affect $$V_{max}.$$

Question 2

A pharmaceutical company is designing a drug to inhibit an enzyme involved in cholesterol synthesis. Which type of inhibition would be most specific for the enzyme’s active site?

Accepted Answer

Competitive inhibition

Question 3

Given the Michaelis-Menten equation $$V = \frac{V_{max} [S]}{K_m + [S]}$$, what is the substrate concentration $$[S] at $$which the reaction velocity $$V is $$half of $$V_{max}$$?

Accepted Answer

$$[S] = K_m$$

Question 4

Which of the following best describes the Lineweaver-Burk plot for an enzyme reaction?

Accepted Answer

A plot of $$1/V$$ versus $$1/[S]$$ that produces a straight line.

Question 5

In noncompetitive inhibition, which kinetic parameter is altered and how?

Accepted Answer

$$V_{max}$$ decreases, $$K_m$$ remains unchanged.

Question 6

A drug binds only to the enzyme-substrate complex and prevents product formation. Which type of inhibition is this, and what is its effect on $$K_m$$ and $$V_{max}$$?

Accepted Answer

Uncompetitive inhibition; decreases both $$K_m$$ and $$V_{max}.$$

Question 7

If an enzyme has a low $$K_m$$, what does this indicate about its affinity for the substrate?

Accepted Answer

The enzyme has high affinity for the substrate.

Question 8

Which of the following drugs acts as a competitive inhibitor in the body?

Accepted Answer

Aspirin inhibiting cyclooxygenase

Question 9

On a Lineweaver-Burk plot, what does the y-intercept represent?

Accepted Answer

$$1/V_{max}$$

Question 10

A patient is given a drug that causes the Lineweaver-Burk plot of an enzyme to show two parallel lines, both with decreased $$V_{max}$$ and $$K_m. $$What type of inhibition is this?

Accepted Answer

Uncompetitive inhibition

Question 11

Which of the following best explains why increasing substrate concentration can overcome competitive inhibition?

Accepted Answer

The substrate and inhibitor compete for the same active site.

Question 12

Which parameter is most important when designing a drug to inhibit an enzyme, according to pharmaceutical industry standards?

Accepted Answer

Binding affinity, as measured by $$K_m$$

Question 13

A biochemist observes that increasing substrate concentration does not reverse the inhibition of an enzyme. Which type of inhibition is most likely occurring?

Accepted Answer

Noncompetitive inhibition

Question 14

Which of the following is a correct interpretation of the slope in a Lineweaver-Burk plot?

Accepted Answer

Slope = $$K_m/V_{max}$$

Question 15

An enzyme reaction is studied at different pH values. At pH values far from the optimum, the reaction rate drops. What is the most likely explanation?

Accepted Answer

Ionization of active site groups affects binding or catalysis.

Question 16

Which of the following best describes the effect of heat on enzyme activity?

Accepted Answer

Heat can cause unfolding and denaturation, reducing activity.

Question 17

A drug binds to an allosteric site on an enzyme, causing a conformational change. The substrate can still bind, but the enzyme activity is reduced. Which type of inhibition is this?

Accepted Answer

Noncompetitive inhibition

Question 18

Which of the following scenarios would result in a decrease in both $$K_m$$ and $$V_{max}$$?

Accepted Answer

Uncompetitive inhibition

Question 19

If an enzyme’s $$V_{max} is $$high, what does this indicate about the reaction?

Accepted Answer

The reaction occurs quickly.

Question 20

A biochemist wants to determine the type of inhibition a drug causes. Which experimental approach is most appropriate?

Accepted Answer

Plot $$1/V_0$ against 1$$/[S]$$ with and without the inhibitor.

Enzyme Kinetics and Enzyme Inhibition: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards