Biology Enzymes MDCAT 2017
PMDC Verified Question 75 of 79
Modified form of Lock and Key model was proposed by:
A
Fischer
B
Rosalind Franklin
C
Koshland
D
Watson
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Koshland
Concept:

The rigidity of the early Lock and Key model failed to explain how some enzymes catalyze reactions for multiple related substrates or exhibit allosteric regulation.

Solution:

  • To resolve this, Daniel Koshland proposed a modified version known as the Induced Fit model in 1959.
  • He postulated that the active site continuously molds itself to the substrate as it binds, maximizing catalytic efficiency.


Why other options are incorrect:

Emil Fischer proposed the original, rigid Lock and Key model. Watson and Rosalind Franklin are famous for their work on the structure of DNA, not enzyme kinetics.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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