Multiple Choice
Which of the following terms describes how rapidly a substrate can undergo a reaction?
3. Energy
Enzyme Kinetics
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If an enzyme is determined to have a low Km what does that say about the reaction?
A
The enzyme binds loosely to the substrate
B
That the speed of the reaction is slow
C
The enzyme binds tightly to the substrate
D
That the speed of the reaction is fast
Verified step by step guidance1
Understand the concept of Km: Km, or the Michaelis constant, is a measure of the substrate concentration required for an enzyme to reach half of its maximum reaction velocity. It is a key parameter in enzyme kinetics.
Interpret the meaning of a low Km value: A low Km indicates that the enzyme reaches its half-maximal velocity at a low substrate concentration, suggesting a high affinity between the enzyme and its substrate.
Relate Km to enzyme-substrate binding: Since a low Km reflects high affinity, it implies that the enzyme binds tightly to the substrate, as it requires less substrate to become significantly active.
Consider the implications for reaction speed: While a low Km indicates strong binding, it does not directly determine the speed of the reaction. Reaction speed is more directly related to Vmax, the maximum rate of the reaction.
Conclude the interpretation: Based on the understanding of Km, the correct interpretation is that a low Km value suggests the enzyme binds tightly to the substrate, rather than indicating the speed of the reaction.
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