Enzymes

• What is the structure of enzymes?

  Tertiary structure proteins
• What is the function of enzymes?

  To catalyze different reactions
• What part of the enzyme is involved in catalyzing reactions?

  The active site
• What is the role of the active site?

  It binds the substrate to form complexes
• What is formed when the substrate binds to the active site?

  Enzyme substrate complexes
• How is the shape of the active site described?

  Specific and unique shape
• What determines the tertiary structure of a protein?

  The sequence of amino acids
• How does the tertiary structure affect the active site?

  It creates a unique shape for binding
• What is the key term related to enzyme action?

  Enzyme substrate complex
• What do enzymes lower to catalyze reactions?

  The activation energy
• What is the lock and key model of enzyme action?

  Enzyme is a lock, substrate is a key
• How does the lock and key model describe enzyme specificity?

  Only complementary shapes can bind
• What happens to the substrate in the enzyme substrate complex?

  It slightly distorts in shape
• What is the induced fit model of enzyme action?

  Active site molds around the substrate
• How does the induced fit model affect the substrate bonds?

  It puts strain on the bonds, weakening them
• What happens to the active site after the reaction?

  It returns to its original shape
• What is the accepted model for how enzymes function?

  The induced fit model
• What is the outcome of the enzyme action?

  Products are released
• Why is the induced fit model important?

  It explains how enzymes lower activation energy
• What is the relationship between enzymes and activation energy?

  Enzymes lower activation energy
• What are the two models of enzyme action?

  • Lock and key model
  • Induced fit model
• What are the key differences between the lock and key model and the induced fit model?

  • Lock and key: fixed shape, exact fit
  • Induced fit: flexible shape, molds around substrate
• What is the process of enzyme action from substrate binding to product release?

  1. Substrate binds to active site
  2. Enzyme-substrate complex forms
  3. Bonds in substrate weaken
  4. Activation energy lowered
  5. Products released
  6. Active site returns to original shape
• What are the factors affecting enzyme action?

  Temperature, pH, substrate concentration, enzyme concentration, inhibitors
• Why do proteins change structure affecting enzyme action?

  They are sensitive to different conditions
• What happens to enzymes at low temperatures?

  Insufficient kinetic energy for collisions
• What occurs when the temperature exceeds the optimum for enzymes?

  The enzyme denatures and active site changes shape
• What causes enzyme denaturation at high temperatures?

  Bonds in the tertiary structure break
• What is the second condition affecting enzyme action?

  pH
• How does pH affect enzyme action?

  High or low pH can cause denaturation
• What happens to the active site at extreme pH levels?

  The active site changes shape and denatures
• What is the optimal pH for most enzymes?

  pH 7
• Do all enzymes have the same optimal pH?

  No, different enzymes have different optimal pHs
• What is the effect of low substrate concentration on enzyme action?

  Lower rate of reaction due to fewer collisions
• What happens when substrate concentration increases?

  Rate of reaction increases until saturation
• What is the limiting factor at low substrate concentrations?

  Substrate concentration
• What occurs when enzyme concentration is low?

  Rate of reaction is limited by enzyme concentration
• What happens at high enzyme concentrations?

  Rate of reaction plateaus due to excess enzymes
• What is the effect of having an indefinite supply of enzyme and substrate?

  Directly proportional increase in rate of reaction
• What are the two types of enzyme inhibitors?

  Competitive and non-competitive inhibitors