Question 1

Which of the following best describes the main difference between the Lock & Key and Induced Fit models of enzyme-substrate interaction?

Accepted Answer

The Lock & Key model involves a rigid active site, while the Induced Fit model involves an active site that changes shape to better fit the substrate.

Question 2

In the context of enzyme catalysis, what is the primary advantage of the Induced Fit model over the Lock & Key model?

Accepted Answer

It explains how enzymes can stabilize the transition state and lower activation energy more effectively.

Question 3

Given the following reaction coordinate diagram, which model (Lock & Key or Induced Fit) is most likely represented if the ES-complex is highly stabilized and the activation energy is not significantly lowered?

Accepted Answer

Lock & Key model

Question 4

Which of the following statements about enzyme-substrate specificity is correct according to the Lock & Key model?

Accepted Answer

The enzyme's active site is complementary in shape to the substrate before binding.

Question 5

A researcher observes that an enzyme undergoes a significant conformational change upon substrate binding, which leads to a lower activation energy for the reaction. Which model does this observation support?

Accepted Answer

Induced Fit model

Question 6

Which of the following best explains why the Induced Fit model is more effective at stabilizing the transition state than the Lock & Key model?

Accepted Answer

The enzyme's active site adapts to the substrate, optimizing interactions that stabilize the transition state.

Question 7

Consider an enzyme-catalyzed reaction where the ES-complex is more stable than the transition state. What is the likely consequence for the reaction rate?

Accepted Answer

The reaction rate will decrease because the activation energy is not sufficiently lowered.

Question 8

Which of the following sequences correctly matches the order of states in the Induced Fit model for an enzyme-catalyzed reaction?

Accepted Answer

Substrate $$\rightarrow$$ Induced Fit $$\rightarrow$$ Transition State $$\rightarrow$$ Product

Question 9

A mutation in an enzyme's active site prevents it from changing shape upon substrate binding. Which model of enzyme action would this mutation most directly disrupt?

Accepted Answer

Induced Fit model

Question 10

Which of the following best describes the role of the enzyme in lowering the activation energy ($$E_a) of a $$reaction according to the Induced Fit model?

Accepted Answer

The enzyme stabilizes the transition state through conformational changes that optimize substrate binding.

Question 11

In a reaction coordinate diagram, which feature would indicate that the enzyme is acting via the Induced Fit model?

Accepted Answer

A lower activation energy ($$E_a) $$due to stabilization of the transition state after substrate binding.

Question 12

Which of the following is a potential drawback of the Lock & Key model in explaining enzyme catalysis?

Accepted Answer

It does not account for the stabilization of the transition state.

Question 13

A patient has a genetic mutation that causes their enzymes to bind substrates too tightly, forming a very stable ES-complex. What is the most likely effect on their metabolism?

Accepted Answer

Their metabolic reactions will proceed more slowly due to poor transition state stabilization.

Question 14

Which of the following best summarizes the sequence of events in the Lock & Key model?

Accepted Answer

Substrate binds to a rigid, complementary active site, forming the ES-complex without significant conformational change.

Question 15

Which of the following is NOT a step in the Induced Fit model of enzyme catalysis?

Accepted Answer

Enzyme active site remains rigid and unchanged during substrate binding.

Question 16

If an enzyme catalyzes a reaction by first binding the substrate and then changing its conformation to better fit the transition state, which model is being described?

Accepted Answer

Induced Fit model

Question 17

Which of the following is a real-world implication of the Induced Fit model for drug design?

Accepted Answer

Drugs can be designed to induce conformational changes in enzymes, enhancing or inhibiting their activity.

Question 18

Which of the following best explains why enzymes do not get consumed in the reactions they catalyze?

Accepted Answer

Enzymes facilitate the reaction by lowering activation energy but are regenerated at the end of the reaction.

Enzyme-Substrate Interaction Models: Lock & Key vs Induced Fit

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