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Physiology Quiz -
Michaelis-Menten Kinetics - Part 4
Michaelis-Menten kinetics is used to describe the rate of a reaction catalyzed by an enzyme as a function of the substrate concentration. This type of analysis is also commonly used to describe the rate of transporter-mediated translocation of ions and molecules across biological membranes. Test your basic knowledge of Michaelis-Menten kinetics by taking this simple quiz.
(1)   A lower numerical value of the Michaelis constant (Km) indicates a lower enzyme/transporter affinity for its substrate.
 True False
(2)   Assume that the reaction catalyzed by an enzyme follows Michaelis-Menten kinetics. The substrate concentration (Km, Michaelis constant) needed to reach 50% of the maximum reaction velocity (Vmax) is 25 μM. What substrate concentration is required to obtain at least 96% of the maximum reaction velocity?
 (A)   250 μM (B)   475 μM (C)   600 μM (D)   1225 μM (E)   2475 μM
(3)   Assume that the reaction catalyzed by an enzyme follows Michaelis-Menten kinetics. The substrate concentration (Km, Michaelis constant) needed to reach 50% of the maximum reaction velocity (Vmax) is 25 μM. What substrate concentration is required to obtain at least 98% of the maximum reaction velocity?
 (A)   250 μM (B)   475 μM (C)   600 μM (D)   1225 μM (E)   2475 μM
(4)   Assume that the reaction catalyzed by an enzyme follows Michaelis-Menten kinetics. The substrate concentration (Km, Michaelis constant) needed to reach 50% of the maximum reaction velocity (Vmax) is 25 μM. What substrate concentration is required to obtain at least 99% of the maximum reaction velocity?
 (A)   250 μM (B)   475 μM (C)   600 μM (D)   1225 μM (E)   2475 μM
(5)   Assume that the reaction catalyzed by an enzyme follows Michaelis-Menten kinetics. If at a substrate concentration of 100 nM, the reaction proceeds at 20% of the maximum reaction velocity (Vmax), what is the Michaelis constant (Km) for this substrate. Km is the substrate concentration needed to reach 50% of Vmax.
 (A)   100 nM (B)   200 nM (C)   400 nM (D)   500 nM (E)   800 nM
(6)   Assume that the reaction catalyzed by an enzyme follows Michaelis-Menten kinetics. If at a substrate concentration of 100 nM, the reaction proceeds at 10% of the maximum reaction velocity (Vmax), what is the Michaelis constant (Km) for this substrate. Km is the substrate concentration needed to reach 50% of Vmax.
 (A)   100 nM (B)   300 nM (C)   500 nM (D)   900 nM (E)   1000 nM