2.12: Practical: Investigate How Enzyme Activity can be Affected by Changes in Temperature

INVESTIGATING EFFECT OF TEMPERATURE ON ENZYME ACTIVITY

Diagram Showing the Spots of Starch and Amylase in Wells

INDEPENDENT VARIABLE: Temperature of Starch Solution (0, 10, 20, 30, 40, 50, 60°C)

METHOD: Test tube of Starch solution is placed in Water bath of set temperature for several minutes (0, 10, 20, 30, 40, 50, 60°C) Solution of Amylase enzyme is added into test tube of Starch solution Immediately after Amylase is added into test tube, pipette is used to add droplets of mixture into wells Immediately after mixture is added into wells, a few drops of Iodine solution is added Process is repeated in increments of fixed time (seconds) until Iodine turns orange, indicating that Starch has completely broken down into Glucose Time taken for Starch to be completely broken down is compared to that of each respective temperature (time taken for Iodine solution to turn orange with each respective temperature)

RESULT: As temperature increases towards optimum (37°C), the rate of amylase activity increases as shown with the decrease in time taken for Iodine solution to turn orange (as temperature increases towards optimum) This is because as temperature increases, Amylase and Starch will gain kinetic energy, vibrating and moving faster This allows more frequent successful enzyme-substrate collisions to occur, increasing the rate in which Starch is broken down into Glucose (which causes Iodine solution to turn orange quicker as Starch is not present), hence increasing enzyme activity) However, as temperature exceeds optimum, Amylase will denature as shown with the increase in time taken for Iodine solution to turn orange (as temperature increases away from optimum) This is because high temperatures causes bonds to vibrate more, increasing chance fo bonds within Amylase enzyme to break When bonds in enzyme break, shape and structure of active site will change, diminishing the ability of Starch (substrate) to bind to active site of Amylase Therefore, Amylase denatures and Starch cannot be broken down into Glucose (which causes Iodine solution to turn orange slower as Starch is present), hence decreasing enzyme activity