Factors Affecting Enzyme Action

• What happens if you increase the temperature of a reaction?

  Particles have more kinetic energy and as a result move faster and collide with each other more often.
• What effect does increasing the temperature have on an enzyme-catalysed reaction?

  Enzyme and substrate molecules collide more frequently resulting in more enzyme-substrate complexes being formed and the rate of reaction increasing.
• What happens when the temperature increase is too high in an enzyme-catalysed reaction?

  The enzyme denatures causing its tertiary structure and active site to change shape resulting in the substrate not being able to bind.
• What effect does changing the pH have on an enzyme-catalysed reaction?

  The enzyme denatures altering the tertiary structure and active site shape so enzyme-substrate complexes can no longer form.
• What do buffer solutions do?

  Maintain a specific pH even if the reaction taking place would cause it to change.
• Why does rate of reaction increase when enzyme concentration increases in a reaction?

  There is a greater number of active sites available and a greater chance of enzyme-substrate complexes forming.
• What happens to the rate of reaction if enzyme concentration increases with sufficient substrates?

  It increases.
• What happens to the rate of reaction if enzyme concentration increases without sufficient substrates and why?

  It will stop increasing as the amount of substrate becomes a limiting factor.
• What happens to the rate of reaction if substrate concentration increases with sufficient enzymes?

  It increases.
• Why does the rate of reaction increase as substrate concentration increases in a reaction?

  There is a greater chance of enzyme-substrate complexes forming.
• What happens to the rate of reaction if substrate concentration increases without sufficient enzymes and why?

  It will stop increasing as all active sites eventually become saturated so any more will have nowhere to bind.
• What is an enzyme inhibitor?

  A substance that binds to an enzyme and decreases its activity.
• What are the two types of reversible inhibitors?

  Competitive inhibitors and non-competitive inhibitors.
• What are competitive inhibitors?

  Molecules that have a similar shape to that of the substrate which allows them to occupy and compete for the active site of an enzyme.
• What does it mean if there is a greater number of competitive inhibitors than substrates?


  The longer it will take for all substrate molecules to occupy an active site.
• What does it mean if there is a greater number of substrates than competitive inhibitors?

  The effects of the inhibitors are reduced
• What happens after an inhibitor leaves an enzymes active site?

  Another inhibitor or substrate, depending on the concentrations, can take its place.
• What are non-competitive inhibitors?

  Molecules that bind to the enzyme at an alternative site which alters the shape of the active site and prevents the substrate from binding to it.
• What effect does increasing the substrate concentration have on non-competitive inhibitors and why?

  No effect as the inhibitors bind at an alternative site.
• What effect does increasing the concentration of inhibitors have on the rate of reaction?

  It reduces the rate of reaction.
• What effect does increasing the substrate concentration have on non-competitive inhibitors and why?


  It increases the rate of reaction as more enzyme-substrate complexes can form.