Digestion of Starch by the Enzyme Amylase
is a large polymer of the monosaccharide glucose.
In order for your body to obtain glucose from
the starch you eat, it must be digested by the enzyme
Amylase is present in human saliva as well as pancreatic juice.
The amylase you will be using is
produced by a fungus.
As you learned in the previous lab, starch can be detected by the addition of a
small amount of iodine solution.
If starch is present the sample will turn dark blue or black when iodine
solution is added, if there is no starch then the sample should be a clear light brown color.
digestion of starch to free glucose should thus result in a clear light brown color when iodine
solution is added.
Partial digestion of starch will result in a color that is somewhat dark but not as
dark as an undigested starch sample.
In the next exercise, you will use iodine solution to determine if
starch is digested by amylase.
Exercise 3 – Digestion of starch by amylase
In this exercise you will set up three reaction tubes.
Two reactions will serve as controls, one lacking the enzyme
and the other lacking starch.
The third reaction will contain both the enzyme amylase and its substrate, starch.
Your three reactions should be performed as follows:
Label three test tubes
and add the indicated components in the order listed.
Mix well and incubate each tube at room temperature for 10 minutes.
Add 3 drops of iodine to each tube, mix and record the results on your worksheet.
Record the color immediately after mixing since it may fade
NOTE: Save your control tubes (tubes 1 & 2) from Exercise 3 for use in Exercise 4.