Physiology Quiz: Michaelis-Menten Kinetics - Part 4

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 (K_m) 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 (K_m, Michaelis constant) needed to reach 50% of the maximum reaction velocity (V_max) 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 (K_m, Michaelis constant) needed to reach 50% of the maximum reaction velocity (V_max) 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 (K_m, Michaelis constant) needed to reach 50% of the maximum reaction velocity (V_max) 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 (V_max), what is the Michaelis constant (K_m) for this substrate. K_m is the substrate concentration needed to reach 50% of V_max.

	(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 (V_max), what is the Michaelis constant (K_m) for this substrate. K_m is the substrate concentration needed to reach 50% of V_max.

	(A) 100 nM
	(B) 300 nM
	(C) 500 nM
	(D) 900 nM
	(E) 1000 nM