AAMC FL Practice Exam

What does the equation V = Vmax[S]/(Km+[S]) describe?

1. The relationship between enzyme kinetics and substrate concentration

2. The linear relationship of enzyme inhibition

3. The bonding process between enzyme and substrate

4. The cyclic nature of enzyme reactions

The correct answer is: The relationship between enzyme kinetics and substrate concentration

The equation V = Vmax[S]/(Km+[S]) is known as the Michaelis-Menten equation, which is fundamental to enzyme kinetics. This equation describes how the rate of an enzyme-catalyzed reaction (V) depends on the concentration of the substrate ([S]). In this context: - Vmax represents the maximum rate of the reaction when the enzyme is saturated with substrate. - Km, or the Michaelis constant, is a measure of how quickly the enzyme binds to the substrate; it reflects the substrate concentration at which the reaction velocity is half of Vmax. This equation shows that as the substrate concentration increases, the velocity of the reaction increases until it reaches a maximum (Vmax). Initially, at low substrate concentrations, the reaction velocity is directly proportional to [S]. However, as [S] continues to rise, the enzyme eventually becomes saturated, leading to a plateau in the reaction velocity (Vmax). The other options do not accurately reflect the significance of this equation. The relationship described is specifically about the kinetics of enzyme reactions and the quantitative relationship between the substrate concentration and the reaction rate, making it the correct choice.