Proteins As Enzymes: Saltine Crackers and Amylase
A protein is a large molecule found in cells. The unique structure of a protein determines its function. Enzymes are proteins that speed up chemical reactions, helping transform one substance into another. The enzyme amylase, found in saliva, changes starch into sugar. In this activity you will experience how this transformation occurs.
One-half of an unsalted saltine cracker
Small paper cup of water
- Remove any gum or candy you may have in your mouth and drink the cup of water.
- Place the saltine in your mouth, but do not chew it. Just hold it in your mouth.
- Note any changes in taste you experience over the next few minutes.
- What did the saltine taste like when you first put it in your mouth?
- Did you experience any change in taste over the time you held the saltine in your mouth? Explain.
- Discuss what you think was happening in your mouth while you held the saltine.
- Answers will vary, but students should not indicate there was any sweet flavor to the cracker.
- Yes. The cracker took on a sweet taste.
- Enzymes were converting starch into sugar.
Verify what actually occurred in this activity by placing a few drops of iodine in a test tube containing a sample of cornstarch mixed with a little water. Iodine turns purple when exposed to a starch. Collect some of your saliva and mix it with cornstarch in another test tube. Allow a few minutes for the reaction. Test this with iodine. What do think will happen?