Enzymes and Kinetics problems
- 1. Which of the following common drugs is not a specific enzyme inhibitor?
Options- A. Iodine
- B. Methotrexate
- C. Sulfbnilamide
- D. Penicillin Discuss
Correct Answer: Iodine
- 2. Which of the following statements is not true?
Options- A. Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates
- B. Enzymes function by overcoming the activation energy barrier of a reaction
- C. Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur
- D. Enzymes only function when they are in intact cells Discuss
Correct Answer: Enzymes only function when they are in intact cells
- 3. Which of the following statements is true for enzymatically catalyzed reaction?
Options- A. The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
- B. Additional substrate molecules are energized to overcome the activation energy of the reaction
- C. The activation energy of the reaction is increased, thus decreasing the likelihood that any substrate molecules will overcome it
- D. The activation energy of the reaction is lowered so that a fewer substrate molecules can overcome it Discuss
Correct Answer: The activation energy of the reaction is lowered so that a larger proportion of the substrate qualifies to overcome it
- 4. The conformational change in an enzyme after the substrate is bound that allows the chemical reaction to proceed, can be explained by
Options- A. induced fit
- B. transition
- C. fit and fine
- D. Pasteur Discuss
Correct Answer: induced fit
- 5. A classical uncompetitive inhibitor is a compound that binds
Options- A. reversibly to the enzyme substrate complex yielding an inactive ESI complex
- B. irreversibly to the enzyme substrate complex yielding an inactive ESI complex
- C. reversibly to the enzyme substrate complex yielding an active ESI complex
- D. irreversibly to the enzyme substrate complex yielding an active ESI complex Discuss
Correct Answer: reversibly to the enzyme substrate complex yielding an inactive ESI complex
- 6. Which of these proteases is not a cysteine active site protease?
Options- A. Calpain
- B. Cathepsin D
- C. Papain
- D. None of the above Discuss
Correct Answer: Cathepsin D
- 7. A competitive inhibitor of an enzyme is usually
Options- A. a highly reactive compound
- B. a metal ion such as Hg2+ or Pb2+
- C. structurally similar to the substrate.
- D. water insoluble Discuss
Correct Answer: structurally similar to the substrate.
- 8. An enzyme is assayed at an initial substrate concentration of 2 x 10-5M. In 6 minute, half of the substrate is used. The Km for the substrate is 2 x 10-3M. The value of k in minute is
Options- A. 0.115
- B. 0.42
- C. 0.093
- D. 6.693 Discuss
Correct Answer: 0.115
- 9. An enzyme and a reactant molecule maintain relationship as
Options- A. a temporary association
- B. an association stabilized by a covalent bond
- C. one in which the enzyme is changed permanently
- D. non complementary binding Discuss
Correct Answer: a temporary association
- 10. Linear inhibition is sometimes called as
Options- A. complete inhibition
- B. incomplete inhibtion
- C. partial inhibition
- D. mixed inhibition Discuss
Correct Answer: complete inhibition
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