Question : 51.The penicillin class of antibiotics inhibitors of an enzyme responsible : 1318505

51.The penicillin class of antibiotics are inhibitors of an enzyme responsible for the formation of bacterial cell walls.  The penicillin covalently binds to a serine residue in the active site of the enzyme, as depicted below.  What type of bond is formed between the penicillin and the active site?

A) hydrogen bond

B) ionic bond

C) glycosidic linkage

D) ester bond

E) acetal bond

52.What is the term for a molecule that is similar in structure and charge distribution to the substrate in an enzyme-catalyzed reaction?

A)effectorD)irreversible inhibitor

B)transition stateE)noncompetitive inhibitor

C)structural analog

53.The arrival of a nerve impulse at the end plate of the nerve axon results in an influx of what ion?

A)  calcium    B)  sodium    C)  potassium    D)  bicarbonate    E)  phosphate

54.The enzyme hexokinase catalyzes the phosphorylation of glucose according to the reaction shown below.  Glucosamine is a competitive inhibitor of hexokinase.  Which of the following best describes the inhibition by glucosamine?

A) Glucosamine stabilizes the active site of the enzyme, preventing glucose-6-phosphate from being released.

B) Glucosamine reacts with glucose, preventing it from binding to the active site of the enzyme.

C) Glucosamine binds to the active site of the enzyme, preventing glucose from binding.

D) Glucosamine binds to the surface of the enzyme, causing a change in the shape of both the enzyme and the active site, preventing glucose from binding.

E) Glucosamine reacts with glucose-6-phosphate, preventing it from being released from the active site.

55.HIV protease inhibitors block the activity of enzymes responsible for which of the following?

A)viral replicationD)antibiotic activity

B)digestionE)pain production

C)oxygen transport

56.The enzyme fumarase is a lyase enzyme that catalyzes the hydration of fumarate to give malate.  What is the structure of malate?

A)

B)

C)

D)

E)

57.What is the function of a lyase enzyme?

A)to catalyze redox reactions

B)to catalyze the transfer of a functional group from one molecule to another

C)to catalyze hydrolysis reactions

D)to catalyze the addition of a group to a double bond or the removal of a group to form a double bond

E)to catalyze the formation or cleavage of a C-C, C-S, C-O, or C-N bond

58.Which statement concerning an enzyme is correct?

A)An enzyme increases the size of the equilibrium constant of the reaction it catalyzes.

B)An enzyme decreases the size of the equilibrium constant of the reaction it catalyzes.

C)An enzyme shifts the equilibrium so that more product is formed when equilibrium is reached.

D)An enzyme increases the rate of a chemical reaction by lowering the activation energy.

E)An enzyme slows down reactions that occur too rapidly to be effective in the body.

59.Which of the following is true for an enzyme catalyzed reaction?

A)The rate of the reaction will increase indefinitely with an increase in the substrate concentration.

B)The rate of the reaction will increase with an increase in the substrate concentration until it reaches a maximum rate.

C)The rate of the reaction will decrease as the substrate concentration increases.

D)The rate of the reaction is unaffected by substrate concentration.

E)The rate of the reaction decreases as the amount of enzyme available increases.

60.A holoenzyme is a functional enzyme composed of what two parts?

A)apoenzyme and cofactorD)transferase and ligase

B)amino acid and NAD+E)substrate and inhibitor

C)substrate and catalyst