Question 1

Which of the following best describes the role of enzymes in biological systems?

Accepted Answer

Enzymes lower the activation energy $$E_a$$ and increase the rate of reaction without altering the equilibrium position.

Question 2

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

Accepted Answer

Transferases

Question 3

The equation $$\Delta G = -RT \ln K_{eq}$$ relates which two properties of a chemical reaction?

Accepted Answer

Free energy change and equilibrium constant

Question 4

Which of the following is NOT a mechanistic way enzymes enhance reaction rates?

Accepted Answer

Changing the overall free energy change $$\Delta G of $$the reaction

Question 5

Which enzyme class is responsible for catalyzing hydrolysis reactions?

Accepted Answer

Hydrolases

Question 6

A patient presents with a deficiency in carbonic anhydrase. Which metal ion is most likely lacking in their diet?

Accepted Answer

Zn$$^{2+}$$

Question 7

Which of the following statements about enzyme specificity is correct?

Accepted Answer

Enzyme specificity is controlled by the unique fit of substrate with the enzyme's active site structure.

Question 8

Which of the following is a common nucleophilic group found in enzyme active sites?

Accepted Answer

R-OH (hydroxyl group)

Question 9

Which coenzyme is responsible for transferring acyl groups in metabolic reactions?

Accepted Answer

Coenzyme A (CoA)

Question 10

The rate enhancement of an enzyme is calculated by comparing the catalyzed rate $$k_{cat} to $$the uncatalyzed rate $$k_{noncat}. If$$ $$k_{cat} = 1.17 	imes 10^8$ s$$^{-1}$$ and k$$_{noncat} = 7.2 	imes $$10^{-8} s$^{-1}$$, what is the rate enhancement?

Accepted Answer

$$1.63 	imes 10$$^{16}$$

Question 11

Which of the following best explains why enzymes do not change the equilibrium position of a reaction?

Accepted Answer

Enzymes lower the activation energy but do not affect $$\Delta G or$$ $$K_{eq}.$$

Question 12

Which of the following is a function of metal ion cofactors in enzyme catalysis?

Accepted Answer

Increase nucleophilicity of water by making it more acidic

Question 13

Which historical figure provided evidence that enzymes, not just chemical catalysts, are responsible for alcoholic fermentation?

Accepted Answer

Louis Pasteur

Question 14

Which of the following best describes the induced fit theory of enzyme specificity?

Accepted Answer

The enzyme changes conformation upon substrate binding to achieve optimal fit.

Question 15

Which of the following amino acid side chains is commonly involved in acid-base catalysis in enzymes?

Accepted Answer

Aspartate (R-COO$$^-)$$

Question 16

A mutation in the active site of hexokinase replaces a key aspartate residue with alanine. What is the most likely effect on enzyme activity?

Accepted Answer

Decreased rate due to loss of acid-base catalysis

Question 17

Which of the following best describes the function of translocases?

Accepted Answer

Move molecules across membranes

Question 18

Which of the following factors can influence enzyme activity in vivo?

Accepted Answer

Both pH and post-translational modifications

Question 19

Which of the following is true about the optimal pH of catalase?

Accepted Answer

It is neutral to slightly basic (around pH 7.6)

Enzymes: Catalysis, Catalytic Groups, and Specificity

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