Question 1

Which of the following best describes how an enzyme increases the rate of a chemical reaction?

Accepted Answer

By lowering the activation energy ($$E_a) $$required to reach the transition state

Question 2

According to the induced fit model of enzyme catalysis, what happens when a substrate binds to an enzyme?

Accepted Answer

The enzyme undergoes a conformational change that stabilizes the transition state

Question 3

Which amino acid is most likely to act as a general base at physiological pH in an enzyme active site?

Accepted Answer

Histidine

Question 4

A competitive inhibitor affects enzyme kinetics by:

Accepted Answer

Increasing $$K_M$$ but leaving $$V_{max}$$ unchanged

Question 5

Which of the following equations correctly represents the Michaelis-Menten equation?

Accepted Answer

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

Question 6

Which statement about the catalytic triad in serine proteases is correct?

Accepted Answer

Serine, histidine, and aspartate work together to activate the serine for nucleophilic attack

Question 7

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

Accepted Answer

Changes in pH can alter the ionization state of amino acid side chains, affecting catalysis

Question 8

Which of the following is true about uncompetitive inhibition?

Accepted Answer

Both $$K_M$$ and $$V_{max}$$ decrease by the same factor

Question 9

Which of the following is a correct statement about the specificity constant ($$\frac{k_{cat}}{K_M}) $$for an enzyme?

Accepted Answer

It is the apparent second-order rate constant for the reaction at low substrate concentration

Question 10

Which of the following best describes the role of Mg$$^{2+} in $$ATP-dependent kinase reactions?

Accepted Answer

Mg$$^{2+}$$ binds to ATP, reducing negative charge and facilitating nucleophilic attack

Question 11

Which of the following is a reducing sugar?

Accepted Answer

A monosaccharide with a free anomeric carbon

Question 12

Which of the following best describes the difference between D- and L-glucose?

Accepted Answer

They are enantiomers, mirror images of each other

Question 13

Which of the following is true about the formation of the cyclic structure of glucose?

Accepted Answer

Cyclization creates a new chiral center at the anomeric carbon

Question 14

Which of the following is a function of proteoglycans in cartilage?

Accepted Answer

They provide hydration and mechanical strength to the extracellular matrix

Question 15

Which of the following best describes feedback inhibition in metabolic pathways?

Accepted Answer

The final product inhibits the first enzyme in the pathway

Question 16

Which of the following is true about the effect of a noncompetitive inhibitor on enzyme kinetics?

Accepted Answer

$$V_{max}$$ decreases and $$K_M$$ remains unchanged if the inhibitor binds equally well to E and ES

Question 17

Which of the following amino acids is most likely to participate in covalent catalysis in an enzyme active site?

Accepted Answer

Cysteine

Question 18

Which of the following best describes the role of the oxyanion hole in serine proteases?

Accepted Answer

It stabilizes the negative charge on the tetrahedral intermediate during catalysis

Question 19

Which of the following is a correct statement about the effect of temperature on DNA double helix stability?

Accepted Answer

Increasing temperature eventually leads to denaturation by making $$\Delta G$$ positive

Enzyme Catalysis and Carbohydrate Structure: Core Concepts in Biochemistry

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