Required Practical 5: Effect of pH on Amylase
Recap:
Amylase is a carbohydrase enzyme that breaks down starch molecules into simple sugars.
Buffer solution: used in biology to control PH
In this practical, we used iodine to test the presence of starch:
-Iodine turns blue-black: starch is present
-Iodine remains orange: starch is no longer present.
Practical Method:
Place one drop of iodine solution into each well of a spotting tile.
Take 3 test tubes: Add 2cm³ of starch solution into 1st test tube, and add 2cm³ of amylase solution to 2nd test tube. 2cm³ of PH5 buffer solution into third test tube.
Place all 3 test tubes in water bath of 30 degrees celcius. Leave them for 10 minutes to allow the solutions to reach the correct temperature
Combine the 3 solutions into 1 test tube and mix with a stirring rod. After, return the test tube into water bath of 30 degress selcius and start a stopwatch.
After 30 seconds, use stirring rod to transfer one drop of solution to a well in a spotting tile that contains the iodine solution: iodine turns blue-black which shows starch is presence.
Take sample every 30 seconds, and continue until the iodine remains orange. Iodine remains orange = starch is no longer present in solution, reaction is complete.
Record time for this in results.
Repeat the whole experiment several times using different ph buffers (e.g. PH6, 7, 8)
Problems with experiment:
Only taking samples every 30 seconds: this may not provide enough data points to accurately assess the rate of reaction, as significant changes in amylase activity could occur between samples. We only have the approx time for reaction to complete, solve this by taking samples every 10 seconds.
