Enzymes

• What are enzymes primarily responsible for in living organisms?


  Enzymes are responsible for making chemical reactions occur.
• Why is raising the temperature not always a good way to speed up reactions in living organisms?


  Raising the temperature can speed up unwanted reactions and damage cells.
• What is a catalyst?


  A catalyst is a substance that increases the speed of a reaction without being changed or used up.
• What are enzymes made of?


  Enzymes are made of proteins, which are composed of chains of amino acids.
• How do enzymes catalyse reactions?


  • Enzymes have an active site with a unique shape.
  • They usually catalyse one specific reaction.
  • The substrate must fit into the active site for the reaction to occur.
• What happens if the substrate does not match the enzyme's active site?


  The reaction will not be catalysed if the substrate does not match the active site.
• What is the 'lock and key' model of enzyme action?


  • It describes how the substrate fits into the enzyme's active site.
  • It is a simplified version of enzyme action.
  • The active site changes shape slightly for a tighter fit (induced fit model).
• What is the effect of temperature on enzyme-catalysed reactions?


  Changing the temperature affects the rate of enzyme-catalysed reactions.
• What happens to an enzyme if the temperature gets too high?


  The enzyme's active site changes shape and the enzyme becomes denatured.
• What is meant by an enzyme being denatured?


  An enzyme is denatured when its shape changes and it can no longer function.
• What is the optimum temperature for enzymes?


  All enzymes have an optimum temperature at which they work best.
• How does pH affect enzyme activity?


  If the pH is too high or too low, the enzyme's shape changes and it can become denatured.
• What is the optimum pH for most enzymes?


  The optimum pH for most enzymes is often neutral pH 7.
• What happens to the bonds holding an enzyme together if the pH is not optimal?


  The bonds holding the enzyme together can change shape, leading to denaturation.
• Why do enzymes have an optimum pH?


  • Enzymes have specific shapes that are crucial for their function.
  • The shape is maintained by bonds that can be affected by pH.
  • Optimal pH ensures the enzyme remains in the correct shape for activity.
• What is the substance that an enzyme acts on called?


  The substance that an enzyme acts on is called the substrate.
• What is the primary function of enzymes?


  Enzymes catalyse (speed up) chemical reactions.
• Why can each enzyme only catalyse one specific reaction?

  Because of the unique shape of its active site.
• How do the enzyme and substrate interact?


  They fit together like a lock and key.
• What effect do high temperatures and extreme pH levels have on enzymes?


  They change the shape of the active site, causing the enzyme to no longer work.
• What is the optimum temperature for enzyme activity mentioned in the material?


  45 °C
• What happens to an enzyme when it is denatured?


  The enzyme's active site changes shape and it can no longer function.
• What is the optimum pH for enzyme activity mentioned in the material?


  The optimum pH is not specified in the material.
• What are the key characteristics of enzymes?


  • Enzymes catalyse specific chemical reactions.
  • Each enzyme has a unique active site.
  • Enzyme-substrate interaction is like a lock and key.
  • Enzymes can be denatured by high temperatures and extreme pH levels.
• What are enzymes classified as in chemical reactions?


  Enzymes are catalysts for chemical reactions.
• How do enzymes affect the speed of chemical reactions?


  Enzymes increase the speed of chemical reactions without being used up.
• What is the role of the active site in an enzyme?


  The active site is complementary to the substrate.
• What happens if the substrate does not fit the active site of an enzyme?


  If the substrate doesn't fit, the reaction won't occur.
• What are the two models of enzyme action?

  1. Lock and Key Model: Substrate fits perfectly into the active site.
  2. Induced Fit Model: Enzyme changes shape slightly when substrate binds.
• What is the effect of temperature on enzyme activity?


  Higher temperatures can increase the rate of reactions but may damage cells.
• How can enzymes be used to speed up non-usable reactions?


  Enzymes can be used to speed up non-usable reactions by increasing temperature.
• Why is it important for enzymes to be specific about which reactions they speed up?


  Specificity ensures that enzymes catalyze only the intended reactions, preventing unwanted side reactions.
• What happens to enzymes during a chemical reaction?


  Enzymes are not changed or used up in the process.
• What is the relationship between enzyme activity and temperature?


  Increased temperature can enhance enzyme activity up to a point, beyond which it may damage cells.
• What is the term for a substance that increases the speed of a chemical reaction?

  Catalyst
• What is the significance of the term "complementary" in relation to enzymes and substrates?


  Complementary means that the shape of the active site matches the shape of the substrate.
• How does the induced fit model differ from the lock and key model?


  The induced fit model suggests that the enzyme changes shape when the substrate binds, while the lock and key model suggests a perfect fit.
• What is the enzyme that catalyses the breakdown of starch to maltose?


  Amylase
• How can you detect the presence of starch in a solution?


  By using iodine solution, which changes from brown-orange to blue-black in the presence of starch
• What are the steps to investigate how pH affects amylase activity?


  1. Add iodine solution to a spotting tile.
  2. Heat water to 35°C in a beaker.
  3. Mix 1 cm³ of amylase and buffer solution (pH 5) in a boiling tube.
  4. Add 5 cm³ of starch solution and start timing.
  5. Sample every 30 seconds until starch is no longer present.
  6. Repeat with different pH buffer solutions.
  7. Control variables for a fair test.