Question 1

Which of the following best explains why hemoglobin, but not myoglobin, displays cooperative binding of oxygen?

Accepted Answer

Hemoglobin contains quaternary structure, allowing subunit interactions that enable cooperativity.

Question 2

A patient presents with acute abdominal pain and elevated serum amylase. Which organ is most likely dysfunctional?

Accepted Answer

Pancreas

Question 3

Which of the following statements about enzyme catalysis is correct?

Accepted Answer

Enzymes lower the activation energy by stabilizing the transition state.

Question 4

Which class of enzyme catalyzes the transfer of a phosphate group from ATP to a substrate?

Accepted Answer

Transferase

Question 5

A mutation in the active site of an enzyme increases its $$K_m. $$What is the most likely effect on enzyme kinetics?

Accepted Answer

The enzyme will require a higher substrate concentration to reach $$\frac{1}{2}V_{max}.$$

Question 6

Which of the following is a prosthetic group commonly found in enzymes and is tightly bound to the protein?

Accepted Answer

FAD

Question 7

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

Accepted Answer

Increases apparent $$K_m$$ but does not change $$V_{max}.$$

Question 8

Which of the following is a key regulatory mechanism for rapidly altering enzyme activity in response to cellular signals?

Accepted Answer

Covalent modification such as phosphorylation

Question 9

Which of the following statements about the Michaelis-Menten equation is correct?

Accepted Answer

At $$[S] = K_m$$, the initial velocity $$v_i = \frac{V_{max}}{2}.$$

Question 10

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

Accepted Answer

Glucose-6-phosphate inhibiting hexokinase in glycolysis

Question 11

A patient with a mutation that increases ubiquitination of HMG-CoA reductase would most likely have which metabolic consequence?

Accepted Answer

Decreased cholesterol synthesis due to increased enzyme degradation

Question 12

Which of the following best describes the Bohr effect in hemoglobin?

Accepted Answer

A decrease in pH decreases hemoglobin's oxygen saturation

Question 13

Which of the following is true regarding allosteric regulation of enzymes?

Accepted Answer

Allosteric effectors bind at a site distinct from the active site and can increase or decrease enzyme activity.

Question 14

Which of the following amino acids is most likely to be phosphorylated during covalent modification of an enzyme?

Accepted Answer

Serine

Question 15

Which of the following best describes the function of lactate dehydrogenase in clinical diagnostics?

Accepted Answer

Elevated levels can indicate liver or muscle damage, depending on the isoform.

Question 16

Which of the following statements about the induced fit model of enzyme action is correct?

Accepted Answer

The enzyme changes conformation upon substrate binding, optimizing the active site for catalysis.

Question 17

Which of the following is a characteristic of noncompetitive inhibition?

Accepted Answer

Decreases $$V_{max}$$ without changing $$K_m$$

Question 18

Which of the following best describes the role of myoglobin in muscle tissue?

Accepted Answer

It binds and stores oxygen released by hemoglobin for use in muscle cells.

Question 19

Which of the following is a likely outcome if a regulatory phosphorylation site on an enzyme is mutated to a non-phosphorylatable residue?

Accepted Answer

The enzyme's activity will likely decrease due to loss of regulation.

Enzyme Function, Regulation, and Oxygen Transport: Biochemistry Study Guide

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