Question 1

Which statement best describes the role of enzymes in metabolic reactions?

Accepted Answer

Enzymes accelerate the rate at which equilibrium is reached without altering the equilibrium position.

Question 2

Which of the following is NOT a property of enzymes?

Accepted Answer

They shift the equilibrium of reversible reactions.

Question 3

What is the main difference between a coenzyme and a metal ion cofactor?

Accepted Answer

Coenzymes are organic molecules, often derived from vitamins, while metal ions are inorganic cofactors.

Question 4

Which equation represents the Michaelis-Menten relationship for enzyme kinetics?

Accepted Answer

$$v = \frac{V_{max} [S]}{K_M + [S]}$$

Question 5

A patient is treated with ethanol after ingesting ethylene glycol. What is the biochemical basis for this treatment?

Accepted Answer

Ethanol acts as a competitive inhibitor, preventing ethylene glycol from being metabolized to toxic products.

Question 6

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

Accepted Answer

It increases $$K_M$$ and leaves $$V_{max}$$ unchanged.

Question 7

Which class of enzymes catalyzes the transfer of functional groups from one molecule to another?

Accepted Answer

Transferases

Question 8

What is the effect of increasing temperature on enzyme-catalyzed reactions?

Accepted Answer

It increases the reaction rate up to an optimum, after which the enzyme may denature and activity decreases.

Question 9

Which statement about isoenzymes is correct?

Accepted Answer

Isoenzymes catalyze the same reaction but may have different kinetic parameters and tissue distributions.

Question 10

Which of the following is a function of the active site of an enzyme?

Accepted Answer

It recognizes and transforms the substrate through catalytic activity.

Question 11

Which enzyme class is responsible for catalyzing the hydrolysis of peptide bonds?

Accepted Answer

Hydrolases

Question 12

What is the effect of a non-competitive inhibitor on enzyme kinetics?

Accepted Answer

It decreases $$V_{max}$$ and leaves $$K_M$$ unchanged.

Question 13

Which of the following best describes the Lineweaver-Burk plot for Michaelis-Menten kinetics?

Accepted Answer

It is a plot of $$1/v$$ versus $$1/[S]$$ and produces a straight line.

Question 14

Which statement about allosteric enzymes is correct?

Accepted Answer

Allosteric enzymes display sigmoidal kinetics due to cooperative substrate binding.

Question 15

In the Monod-Changeux-Wyman (concerted) model of allosteric regulation, which statement is true?

Accepted Answer

All subunits switch between T and R states simultaneously.

Question 16

Which of the following is a real-life example of feedback inhibition in metabolic pathways?

Accepted Answer

The final product of a pathway inhibits an enzyme that acts early in the same pathway.

Question 17

Which parameter is a measure of the affinity of an enzyme for its substrate?

Accepted Answer

$$K_M$$

Question 18

Which of the following statements about proenzymes (zymogens) is correct?

Accepted Answer

Proenzymes require activation by cleavage of a peptide segment.

Question 19

Which of the following is true regarding the effect of substrate concentration on enzyme-catalyzed reaction rate?

Accepted Answer

At very high substrate concentrations, the reaction rate is independent of substrate concentration.

Question 20

Which statement best describes the role of coenzymes in enzymatic reactions?

Accepted Answer

Coenzymes participate in the reaction and are often regenerated for reuse.

Enzymology: Structure, Function, and Kinetics of Enzymes

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