3. Enzymes

Question 1

Lock and Key Model

Answer 1

Key has a specific shape that fits and operates only a single lock. Substrate will only fit the active site of one particular enzyme.

• Support–enzymes are specific in the reaction they catalyze.
• Limitation–enzyme shape IS altered by the binding molecule, the structure is flexible.

Question 2

Induced Fit Model

Answer 2

Enzymes are flexible, has a general shape but this alters in the presence of the substrate.

• explains how other molecules aft enzyme activity
• explains how activation energy is lowered