Which of the following sentences best describes what happens during competitive inhibition of an enzyme?

Question

BlackTom AI · Accepted Answer

Competitive inhibition occurs when an inhibitor binds to the active site of an enzyme, directly competing with the substrate for the same binding pocket.

1. Relevant knowledge points and concepts
- Active site: region of an enzyme where substrate binds and chemistry occurs.
- Competitive inhibitor: a molecule structurally similar to the substrate that occupies the active site reversibly.
- Michaelis–Menten consequences: competitive inhibition increases apparent Km (lower substrate affinity) but does not change Vmax (maximum rate) because sufficiently high [S] outcompetes the inhibitor.
- Mathematical form: Km_app = Km(1 + [I]/Ki), where Ki is the inhibitor dissociation constant.

2. Step-by-step reasoning
- If an inhibitor occupies the active site, substrate cannot bind at that moment; therefore effective substrate binding is reduced.
- Because binding is competitive and reversible, raising substrate concentration can restore enzyme activity by outcompeting the inhibitor.
- This behavior matches the definition of competitive inhibition.

3. Calculations and intermediate steps
- Michaelis–Menten with inhibitor: V = (Vmax [S]) / (Km(1 + [I]/Ki) + [S]).
- Solve for apparent Km: Km_app = Km(1 + [I]/Ki).
- Lineweaver–Burk: 1/V = (Km(1+[I]/Ki)/Vmax)(1/[S]) + 1/Vmax. The y-intercept (1/Vmax) remains unchanged, confirming Vmax is unchanged while slope increases (apparent Km increases).

4. Why the correct answer is correct
- "An inhibitor binds to the active site of an enzyme" precisely describes the physical competition between substrate and inhibitor for the same site, and predicts the kinetic effects noted above, matching textbook definition of competitive inhibition.

5. Why other options are incorrect
- "An enzyme is covalently modified by an inhibitor": describes irreversible inhibition (suicide/inactivators), not competitive (usually reversible).
- "Two substrates compete for binding": describes substrate competition, not inhibition by a separate inhibitor molecule.
- "An enzyme is activated by an inhibitor": contradicts the concept of inhibition.
- "An inhibitor binds to an allosteric site": describes noncompetitive or allosteric inhibition, not competitive inhibition.

6. Conclusion
The correct answer is "An inhibitor binds to the active site of an enzyme," which matches the provided answer.

Which of the following sentences best describes what happens during competitive inhibition of an enzyme?单项选择题

类似问题

How does a competitive inhibitor affect Km and Vmax ?

Which type of enzyme inhibitor does not affect the maximal velocity of a reaction?

A competitive inhibitor of an enzyme:

A competitive inhibitor of an enzyme:

This type of inhibition is ___. We know because . In this type of inhibition, _ is forbidden.

9. This figure describes inhibition of an enzyme by ____________________.

Which of the following is NOT correct about a competitive inhibitor of an enzyme?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单

Which of the following sentences best describes what happens during competitive inhibition of an enzyme?单项选择题

类似问题

How does a competitive inhibitor affect Km and Vmax ?

Which type of enzyme inhibitor does not affect the maximal velocity of a reaction?

A competitive inhibitor of an enzyme:

A competitive inhibitor of an enzyme:

This type of inhibition is _______________. We know because __________________. In this type of inhibition, ___________ is forbidden.

9. This figure describes inhibition of an enzyme by ____________________.

Which of the following is NOT correct about a competitive inhibitor of an enzyme?

更多留学生实用工具

希望你的学习变得更简单

This type of inhibition is ___. We know because . In this type of inhibition, _ is forbidden.