Enzyme action

• What type of proteins are enzymes?

  Enzymes are tertiary structure proteins
• What is the role of the active site in enzymes?

  The active site attaches to a substrate to catalyse a reaction
• What is the term for the part of the enzyme that attaches to the substrate?

  The active site
• Why is the shape of the active site specific and unique?

  It is due to the specific folding and bonding in the tertiary structure of the protein
• How does the primary structure of a protein influence its tertiary structure?

  The sequence of amino acids determines where bonds are formed and how the polypeptide chain folds
• What does it mean for substrates to be complementary in shape to the active site?

  It means they fit together perfectly for the reaction to occur
• What is the enzyme-substrate complex?

  • It is the combination of the substrate and the active site together
  • Formed when the substrate attaches to the enzyme
• What is activation energy?

  It is the energy required for a reaction to occur
• What does the lock and key model suggest about enzyme function?

  • The enzyme is like a lock and the substrate is like a key
  • The active site is a fixed shape
  • Substrates fit into the active site due to complementary shape
• How do enzymes affect activation energy?

  Enzymes lower the activation energy needed for the reaction to occur
• What happens when the enzyme-substrate complex forms according to the lock and key model?

  The charged groups within the active site slightly distort, lowering the activation energy
• What is the induced fit model of enzyme action?

  • The enzyme is like a glove and the substrate is like a hand
  • The active site changes shape to fit the substrate
  • This puts strain on the substrate's bonds, lowering activation energy
• How does the induced fit model differ from the lock and key model?

  The induced fit model allows the active site to change shape to fit the substrate
• What are intracellular enzymes?

  • Enzymes that act within the cells that produce them
  • Example: Catalase, which breaks down hydrogen peroxide
• What happens to the enzyme's active site after the reaction in the induced fit model?

  The active site returns to its original shape
• What are extracellular enzymes?

  • Enzymes that act outside the cells that produce and secrete them
  • Examples:
  • Amylase: breaks down starch into maltose
  • Trypsin: breaks down proteins into smaller polypeptides