Investigating Enzymatic Reactions

• What enzyme catalyzes the breakdown of starch?

  Amylase
• How can you detect the presence of starch?

  Using iodine solution
• What is the procedure to investigate pH's effect on amylase activity?

  1. Add iodine solution to spotting tile wells.
  2. Heat water to 35 °C in a beaker.
  3. Mix amylase and buffer solution in a boiling tube.
  4. Add starch solution and start timing.
  5. Sample every 30 seconds until starch is gone.
  6. Repeat with different pH buffer solutions.
  7. Control variables for a fair test.
• What temperature should the water be heated to in the experiment?

  35 °C
• What is the purpose of using a thermometer in the experiment?

  To measure the temperature of the water
• What should you do immediately after adding starch solution to the boiling tube?

  Mix the contents and start the stop clock
• How do you determine when starch is no longer present in the solution?

  When iodine remains browny-orange
• What variables should be controlled in the experiment?

  • Concentration of amylase solution
  • Volume of amylase solution
  • Temperature of the water
• What is the formula to calculate the rate of reaction?

  Rate = 1000 / time
• If the time taken for amylase to break down starch at pH 6 is 90 seconds, what is the rate of reaction?

  $11 \text{ s}^{-1}$
• How do you calculate the rate of reaction based on change over time?

  Divide the amount changed by time taken
• If 24 cm³ of oxygen is released in 50 seconds, what is the rate of reaction?

  $0.48 \text{ cm}^3/\text{s}$
• How can you adapt the experiment to investigate temperature effects on amylase activity?

  Use a water bath at different temperatures
• If 36 cm³ of product is released in 2 minutes, how do you calculate the rate of reaction in cm³/s?

  Rate = $36 \text{ cm}^3 / 120 \text{ s}$
• What are the factors that can affect the rate of amylase activity?

  • pH levels
  • Temperature
  • Concentration of substrates
  • Concentration of enzymes