Enzymes and Kinetics problems
- 1. When an enzyme is functioning at Vmax, the rate of the reaction is limited by
Options- A. the number of collisions between enzyme and substrate
- B. the number of substrate molecules in the reaction
- C. the concentration of the substrate
- D. the rate at which the enzyme can convert substrate to product Discuss
Correct Answer: the rate at which the enzyme can convert substrate to product
- 2. If a reaction occurs in the absence of inhibitor with rate ?0 and in the presence of inhibitor with rate ?i, the degree of inhibition is defined as
Options- A. (?0 - ?i)/?0
- B. (?0 + ?i)/?0
- C. (?0?i)/?0
- D. (?0-?i)/?i Discuss
Correct Answer: (?0 - ?i)/?0
- 3. Which of the following step is assumed to be the slowest step in the Michaelis Menten equation?
Options- A. The substrate consuming step
- B. The product releasing step
- C. Formation of enzyme substrate complex
- D. None of these Discuss
Correct Answer: The product releasing step
- 4. The ratio of the amount of a protein present in a sample, which is used as a measure of purification, is known as
Options- A. specific activity
- B. relative activity
- C. purity ratio
- D. all of these Discuss
Correct Answer: specific activity
- 5. Which category of enzymes belongs to class 5 in the international classification?
Options- A. Hydrolases
- B. Isomerases
- C. Oxido-reductases
- D. Cyclase Discuss
Correct Answer: Isomerases
- 6. Predominantly uncompetitive inhibition may be called when
Options- A. competitive inhibition is greater than uncompetitive inhibition
- B. competitive inhibition is smaller than uncompetitive inhibition
- C. competitive inhibition is equal to uncompetitive inhibition
- D. none of the above Discuss
Correct Answer: competitive inhibition is greater than uncompetitive inhibition
- 7. When substrate [S] = KM (Michaelis-Menten constant), the velocity of an enzyme catalyzed reaction is about
Options- A. 0.1 * Vmax
- B. 0.2 * Vmax
- C. 0.5 * Vmax
- D. 0.9 * Vmax Discuss
Correct Answer: 0.5 * Vmax
- 8. A classical noncompetitive inhibitor has
Options- A. no effect on substrate binding
- B. no effect on substrate binding and vice versa
- C. significant effect on substrate binding
- D. significant effect on substrate binding and vice versa Discuss
Correct Answer: no effect on substrate binding and vice versa
- 9. The rate equation in non-competitive inhibition based on Michaelis Menten equation is given by
Options- A. rmaxS/(Km + S)(1+I/Ki)
- B. rmaxE/(Km (1+I/Ki)+S))
- C. VmaxS/(Km + S)(1+I/Ki)
- D. rmaxS/Km Discuss
Correct Answer: rmaxS/(Km + S)(1+I/Ki)
- 10. The initial velocity, V0, of an enzyme catalyzed reaction reaches Vmax as
Options- A. [S] = KM
- B. [S] = 10 * KM
- C. 1/[S] = 1/KM
- D. 1/[S] ? 0 Discuss
Correct Answer: 1/[S] ? 0
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