Question 1

Which class of enzyme is responsible for catalyzing the transfer of functional groups from one molecule to another, and what is a real-life example of this enzyme's function?

Accepted Answer

Transferases; catalyze the transfer of a phosphate group from ATP to glucose during glycolysis

Question 2

According to the Michaelis-Menten equation, what happens to the initial reaction velocity $$v_0 as $$substrate concentration $$[S]$$ increases and becomes much greater than $$K_m$$?

Accepted Answer

$$v_0$$ approaches a maximum value, $$V_{max}$$, and becomes independent of $$[S]$$

Question 3

A patient is given a drug that acts as a competitive inhibitor for an enzyme. Which of the following changes would you expect to see in the Lineweaver-Burk plot for this enzyme?

Accepted Answer

The $$V_{max}$$ remains the same, but the $$K_m$$ increases

Question 4

Which of the following best describes the meaning of $$K_m in $$the Michaelis-Menten equation?

Accepted Answer

$$K_m is $$the substrate concentration at which the reaction rate is half of $$V_{max}$$

Question 5

Given the Michaelis-Menten equation $$v_0$$ = \frac{V_{max}[S]}{K_m + [S]}$$, what is the value of v_0$ when $$[S] = K_m$$?

Accepted Answer

$$v_0$$ = \frac{V_{max}}{2}$$

Question 6

A researcher increases the enzyme concentration in a reaction while keeping substrate concentration constant and in excess. What effect will this have on $$V_{max}$$ and $$K_m$$?

Accepted Answer

$$V_{max}$$ increases, $$K_m$$ remains unchanged

Question 7

Which of the following statements about the Lineweaver-Burk plot is correct?

Accepted Answer

It is a plot of $$1/v_0$ versus 1$$/[S]$$ and is linear

Question 8

A mutation in an enzyme's active site increases its affinity for the substrate. How would this likely affect the $$K_m$$ value?

Accepted Answer

$$K_m$$ would decrease

Question 9

Which enzyme class is responsible for catalyzing the hydrolytic cleavage of a molecule into two smaller molecules, and what is a common biological example?

Accepted Answer

Hydrolases; digestive enzymes breaking down proteins in the stomach

Question 10

If an enzyme-catalyzed reaction is operating at $$V_{max}$$, which of the following is true about the enzyme and substrate concentrations?

Accepted Answer

All enzyme active sites are occupied by substrate

Question 11

A patient with a genetic disorder has a defective ligase enzyme. Which cellular process is most likely to be directly affected?

Accepted Answer

Joining of DNA fragments during DNA replication

Question 12

Which of the following best explains why increasing substrate concentration does not always result in a proportional increase in reaction velocity for enzyme-catalyzed reactions?

Accepted Answer

Enzyme active sites become saturated at high substrate concentrations

Question 13

Which of the following equations represents the Michaelis-Menten equation for enzyme kinetics?

Accepted Answer

$$v_0$$ = \frac{V_{max}[S]}{K_m + [S]}$$

Question 14

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

Accepted Answer

$$\frac{1}{V_{max}}$$

Question 15

A scientist is studying an enzyme that catalyzes the rearrangement of atoms within a molecule. Which class does this enzyme belong to?

Accepted Answer

Isomerases

Question 16

If the initial substrate concentration $$[S] is $$much less than $$K_m$$, how does the initial velocity $$v_0$$ relate to $$[S]$$?

Accepted Answer

$$v_0 is $$proportional to $$[S]$$

Question 17

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

Accepted Answer

It is equal to $$-\frac{1}{K_m}$$

Question 18

A new drug is found to decrease the $$V_{max} of an $$enzyme-catalyzed reaction without affecting $$K_m. $$What type of inhibitor is this drug most likely to be?

Accepted Answer

Noncompetitive inhibitor

Question 19

Which of the following best describes the role of rate constants ($$k_1$$, $$k_2$$, $$k_3$$, $$k_4) in $$enzyme kinetics?

Accepted Answer

They relate the rate of a reaction to the concentration of reactants

Enzyme Kinetics: Principles and Applications

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