RP05 - Enzymes

• What is the aim of the RP05 enzyme practical?

  To investigate the effect of pH on the rate of amylase enzyme activity using continuous sampling with iodine to measure the time for starch digestion at different pH values.
• What equipment is needed for the RP05 enzyme practical?

  (Group 1: Test tubes and accessories)

  Test tubes, Test tube rack, Measuring cylinder, Syringes, Glass rod
• What mnemonic can be used to remember Group 1:

  Test tubes and accessories

  "Tough Tasks Make Smart Goals"
• What equipment is needed for the RP05 enzyme practical?

  (Group 2: Solutions)

  Starch solution, Amylase solution, Iodine solution, Buffered solutions
• What mnemonic can be used to remember Group 2: Solutions

  "Some Amazing, Inspiring Buffs"
• What equipment is needed for the RP05 enzyme practical?

  (Group 3: Temperature control)

  Water bath, Thermometer
• What mnemonic can be used to remember Group 3: Temperature Control

  "Warm Time"
• What is the first step of the RP05 enzyme practical?

  Label each well of a tile with the time (starting from 0 onwards) and add a drop of iodine solution to each well.
• What is added to each labeled test tube in step 2 of the method?

  Add 2 cm³ of buffer solution (pH 3.0 to 7.0) into each labeled test tube using a syringe.
• What is the purpose of equilibrating the solutions in step 3?

  To ensure all solutions (buffer, starch, and amylase) are at the same temperature, allowing consistent enzyme activity.
• What is the fourth step in the RP05 practical?

  Add 2 cm³ of amylase solution to one test tube containing buffer solution.
• What happens in step 5 of the RP05 practical?

  Add 2 cm³ of starch solution into the same test tube as the amylase solution and start timing immediately.
• How is the reaction monitored in step 6?

  Use a glass rod to transfer a drop of the mixture to the well labeled ‘0’ on the spotting tile.
• What happens in step 7 of the RP05 practical?

  Repeat step 6 every 30 seconds, rinsing the glass rod between tests, until the iodine remains brown (no starch present).
• How is the enzyme reaction rate calculated in step 8?

  Calculate the rate by using the formula:

  (1) / (time taken for iodine to stay brown)
• What is done in step 9 of the RP05 practical?

  Repeat steps 2-8 for different buffer solutions at various pH values to investigate the effect of pH on enzyme activity.
• What is done in step 10 of the RP05 practical?

  Plot a graph of the enzyme reaction rate against the pH values tested.
• What is a potential source of error in the RP05 practical?

  Intervals between tests may be too long to accurately measure the time taken for starch to be completely broken down.
• What are the potential hazards in the RP05 practical?

  Be careful when using hot water, and if using a Bunsen burner, tie long hair back and wear goggles.