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The lock-and-key model of enzyme action was proposed by

Answer: Fischer.

  • A Koshland
  • B Fischer
  • C Michaelis
  • D Pauling

Correct answer: B. Fischer

Explanation: Emil Fischer proposed the lock-and-key model in 1894, suggesting the enzyme active site is rigid and complementary to the substrate. Koshland later proposed the induced fit model in 1958.

Enzyme Kinetics: Rate vs Substrate Concentration[Substrate]Reaction rateVmaxKm½VmaxCurve flattens at high [S]: ALL enzyme active sites are occupied (saturation)

As substrate concentration rises, reaction rate increases steeply at first, then plateaus at Vmax once every enzyme molecule is working at full capacity; Km is the substrate concentration giving half-maximal rate, and a LOWER Km means the enzyme reaches that rate with less substrate (higher affinity).

Concept context

Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.

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