required practical amylase

• Amylase breaks down starch molecules into simple sugars
• first place one drop of iodine solution into each well of a spotting tile (test the presence of starch)
• take 3 test tubes, first test tube add 2cm cubed of starch solution. second test tube add 2cm cubed of amylase solution and in the third test tube add 2cm cubed of pH 5 buffer solution. Buffer solution is used to control the pH.
• Then take the three test tubes and place them in a water bath at 30°C. Leave them for 10 minutes to allow the solutions to reach the correct temperature.
• Now combine all 3 solutions into one test tube and mix with a stirring rod. Immediately return to the water bath and start a stopwatch.
• after 30 seconds, use the stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine. The iodine should turn blue-black if starch is present.
• now we take a sample every 30 seconds and we continue until the iodine remains orange.
• when the iodine remains orange, this tells us starch is no longer present and the reaction has completed. record the time for this and repeat the experiment several times using different pH buffers.
• The colour change tends to be gradual and this means it could be difficult to tell when the reaction has finished