Biology Enzymes MDCAT 2017
PMDC Verified Question 76 of 79
Which of the following type of inhibitor can be neutralized by adding more substrate into reaction?
A
Irreversible non-competitive
B
Reversible inhibitor
C
Irreversible competitive
D
Irreversible inhibitor
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Reversible inhibitor
Concept:

The effect of competitive inhibitors relies purely on a statistical game of chance regarding which molecule collides with the active site first.

Solution:

  • A competitive reversible inhibitor weakly binds to the active site without permanently damaging it.
  • Because it is a numbers game, if you drastically increase the concentration of the true substrate, the substrate molecules vastly outnumber the inhibitors.
  • The sheer probability of a true substrate colliding with the active site becomes so high that the effect of the inhibitor is completely neutralized.
  • (Note: The provided options historically list "Reversible inhibitor" as the correct choice for this competitive mechanism).


Why other options are incorrect:

Any irreversible inhibitor (competitive or non-competitive) forms permanent covalent bonds that destroy the enzyme; adding more substrate cannot save a destroyed active site.

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