Rates of reaction

• What factors influence the rate of an enzyme-controlled reaction?

  Temperature, pH, substrate concentration, enzyme concentration
• How can the effect of a variable on the rate of reaction be determined?

  By changing a single variable and measuring its effect
• Why is it important to keep all other variables constant during the experiment?

  To prevent them from influencing the results
• When is the initial rate of reaction measured?

  When the concentration of reactants is known
• Why is the initial rate of reaction high in enzyme-controlled reactions?

  Because enzymes act as biological catalysts
• What is the equipment needed for the experiment?

  Milk powder solution, trypsin solution, test tubes
• What is the method for preparing trypsin solutions?

  • Dilute stock solution with distilled water
  • Create concentrations of 0.2%, 0.4%, 0.6%, and 0.8%
• What is the purpose of the control in the experiment?

  To set the colorimeter absorbance to zero
• How is absorbance measured during the experiment?

  At 15 second intervals for 5 minutes
• What should be done after measuring absorbance?

  Rinse the cuvette with distilled water
• What are the risks associated with the experiment?

  • Broken glass: Cuts from sharp objects
  • Hot liquids: Scalding
  • Enzymes: Allergies
• What safety precautions should be taken with broken glass?

  Handle carefully and keep away from edges
• What should be done in case of a burn from hot liquids?

  Run burn under cold water and seek help
• What is the white protein found in milk?

  Casein
• What does trypsin do to casein in milk?

  Hydrolyzes it, causing milk to turn colorless
• How does increasing trypsin concentration affect the rate of reaction?

  It increases the number of enzyme-substrate complexes
• What happens to the rate of reaction at optimum enzyme concentration?

  The rate of reaction increases until it plateaus
• What limits the rate of reaction when all active sites are occupied?

  Substrate concentration
• How can the procedure be modified to measure substrate concentration effects?

  • Dilute milk suspension for different concentrations
  • Control concentration of trypsin