Multiple Choice
Which statement best describes a key property of enzymes regarding their use in repeated catalytic cycles?
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6. Enzymes and Enzyme Kinetics
Enzymes
Multiple Choice
In a typical enzyme-catalyzed reaction where the enzyme remains chemically unchanged, how many times can a single enzyme molecule be used to catalyze the conversion of substrate to product?
A
A fixed number determined solely by the initial substrate concentration
B
Exactly twice; once for binding substrate and once for releasing product
C
Only once; the enzyme is consumed as a reactant during catalysis
D
Many times; it can catalyze repeated reaction cycles until it becomes denatured or otherwise inactivated
Verified step by step guidance1
Understand the role of an enzyme in a biochemical reaction: enzymes act as catalysts, meaning they speed up the reaction without being consumed or permanently altered in the process.
Recall the definition of a catalyst: it participates in the reaction by binding to the substrate, converting it to product, and then releasing the product while remaining unchanged.
Recognize that because the enzyme is not consumed, it can bind to multiple substrate molecules sequentially, catalyzing many reaction cycles.
Consider factors that limit the number of times an enzyme can catalyze a reaction, such as enzyme denaturation or inactivation, but not substrate concentration or a fixed number of uses.
Conclude that a single enzyme molecule can catalyze the conversion of substrate to product many times, repeatedly cycling through binding, catalysis, and release steps until it is no longer functional.
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