Question 1

Which of the following best describes the role of an enzyme in a biochemical reaction?

Accepted Answer

Enzymes lower the activation energy by stabilizing the transition state.

Question 2

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

Accepted Answer

$$K_m$$

Question 3

A Lineweaver-Burk plot of an enzyme reaction shows that the y-intercept increases while the x-intercept remains unchanged after adding an inhibitor. What type of inhibition is this?

Accepted Answer

Noncompetitive inhibition

Question 4

Which of the following statements about the catalytic triad in serine proteases is correct?

Accepted Answer

The catalytic triad (serine, histidine, aspartate) facilitates nucleophilic attack on the peptide bond.

Question 5

Which of the following best describes the difference between lock-and-key and induced-fit models of enzyme-substrate binding?

Accepted Answer

Induced-fit model suggests the enzyme undergoes conformational change to accommodate the substrate.

Question 6

Which of the following is a correct statement about the role of ATP as a cofactor?

Accepted Answer

ATP acts as a cofactor by donating phosphate groups in group transfer reactions.

Question 7

Which of the following best distinguishes essential ions from coenzymes?

Accepted Answer

Essential ions are required for enzyme activity and are typically metal ions, while coenzymes are organic molecules that participate in catalysis.

Question 8

Which of the following statements about monosaccharides is correct?

Accepted Answer

Aldoses contain an aldehyde group, while ketoses contain a ketone group.

Question 9

Which of the following best describes the formation of a glycosidic bond in disaccharides?

Accepted Answer

A glycosidic bond forms between the anomeric carbon of one monosaccharide and a hydroxyl group of another.

Question 10

Which of the following is a reducing sugar?

Accepted Answer

Lactose

Question 11

Which of the following best describes the difference between O-linked and N-linked glycoproteins?

Accepted Answer

O-linked glycoproteins have carbohydrates attached to the oxygen atom of serine or threonine, while N-linked glycoproteins have carbohydrates attached to the nitrogen atom of asparagine.

Question 12

Which of the following statements about the ABO blood classification is correct?

Accepted Answer

Blood type is determined by the presence of specific glycoproteins on the surface of red blood cells.

Question 13

Which of the following is NOT a component of a nucleotide?

Accepted Answer

Carboxyl group

Question 14

Which of the following correctly distinguishes DNA nucleotides from RNA nucleotides?

Accepted Answer

DNA nucleotides contain deoxyribose, while RNA nucleotides contain ribose.

Question 15

Which of the following best describes the directionality of nucleic acid synthesis?

Accepted Answer

Nucleotides are added to the 3' end of the growing chain.

Question 16

Which of the following correctly describes the Watson-Crick base pairing in DNA?

Accepted Answer

A pairs with T via two hydrogen bonds, and G pairs with C via three hydrogen bonds.

Question 17

Which of the following is a function of NAD(P)+/NAD(P)H as a cofactor?

Accepted Answer

Catalyzing redox reactions by accepting or donating electrons

Question 18

A patient is given a mechanism-based inhibitor for an enzyme involved in cholesterol synthesis. Which of the following best describes the action of this inhibitor?

Accepted Answer

It is converted by the enzyme into a reactive species that irreversibly inactivates the enzyme.

Question 19

Which of the following best describes the proximity effect in enzyme catalysis?

Accepted Answer

The enzyme brings substrates together in the correct orientation to facilitate the reaction.

BCH 351 Exam 2 Study Guide: Enzymes, Carbohydrates, and Nucleic Acids

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