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

Question

BlackTom AI · Accepted Answer

Competitive inhibitors increase the apparent Km (shift the substrate curve to the right) without changing Vmax, so the red curve in the figure matches that pattern.

1) Relevant knowledge points and concepts
- Michaelis–Menten kinetics: Vmax is the maximum reaction velocity; Km is the substrate concentration at which Vo = Vmax/2 and is an inverse measure of apparent affinity.
- Effects of inhibitors: Competitive inhibitors compete with substrate for the active site, increasing the apparent Km (need more substrate to reach the same rate) but not changing Vmax. Noncompetitive inhibitors reduce Vmax (less active enzyme) but do not change Km.

2) Step-by-step reasoning using the graph
- Identify Vmax: both the blue (enzyme alone) and red (enzyme + inhibitor) curves asymptotically approach the same dashed Vmax line, so Vmax is unchanged by the inhibitor.
- Identify Km from the graph: Km is the [substrate] when reaction velocity = Vmax/2. The blue curve reaches Vmax/2 at a lower [S] (Km1) than the red curve (Km2), so Km2 > Km1.
- Interpretation: an increase in apparent Km with no change in Vmax is the hallmark of competitive inhibition.

3) Calculations / intermediate step illustrated
- By definition Vo = Vmax/2 when [S] = Km. Graph shows:
  - For enzyme alone (blue): [S] = Km1 at Vo = Vmax/2.
  - For enzyme + inhibitor (red): [S] = Km2 at Vo = Vmax/2.
  - Since Km2 > Km1, apparent Km increases in presence of inhibitor.

4) Why the correct answer is correct
- The red curve’s rightward shift (higher Km) with identical Vmax directly matches the behavior expected for a competitive inhibitor.

5) Why other options are incorrect
- A (a substrate): a substrate would not reduce velocity at given [S] in this way; it’s not an inhibitor.
- C (non-competitive inhibitor): noncompetitive inhibition lowers Vmax while Km remains unchanged—contrary to the graph.
- D (none): graph matches a known inhibition type, so this is incorrect.

6) Conclusion
- The figure describes inhibition by a competitive inhibitor. This confirms the correct choice: B. a competitive inhibitor.

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

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

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.

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

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

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.

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.