Enzyme action

• What is the role of enzymes in chemical reactions?

  They speed up the rate of chemical reactions by acting as catalysts.
• Do enzymes get used up in reactions?

  No
• What are enzymes made of?

  Proteins with tertiary structure.
• What is the specific part of an enzyme where the substrate binds?

  The active site.
• What forms when an enzyme binds to a substrate?

  An enzyme-substrate complex
• What happens to the enzyme after the reaction has occurred?

  The enzyme goes on to make more enzyme-substrate complexes.
• Why are enzymes specific?

  Their active site will only bind to one substrate
• How do we describe the shape of the active site of an enzyme?

  It is complementary to the shape of the substrate
• How do enzymes speed up metabolic reactions?

  By lowering the activation energy of a reaction.
• Why do enzymes allow reactions to occur at lower temperatures?

  They either reduce repulsion between substrates or put strain on substrate bonds.
• Describe the induced-fit model of enzyme action.

  • The enzyme active site is not initially complementary to the substrate
  • the active site moulds around the substrate
  • this puts tension on bonds
  • lowers the activation energy
• Describe the lock and key model of enzyme action.

  Suggests that the enzyme's active site is rigid and exactly complementary to the shape of the substrate.