Salivary amylase is a digestive enzyme secreted in saliva that starts the digestion of complex

EXERCISE 2: INVESTIGATING SALIVARY AMYLASE

Salivary amylase is a digestive enzyme secreted in saliva that starts the digestion of complex carbohydrates into smaller polysaccharides. Pancreatic amylase further digests the polysaccharides in the small intestines, and carbohydrase finishes the process by producing monosaccharides that are small enough to be absorbed into the bloodstream. Iodine will react with complex carbohydrates, such as starch. The normal yellowish color of the solution will turn blue-black in the presence of starch. If starch is absent or has been broken down to smaller sugars, the color will not change.

MATERIALS:
 
•   A solution consisting of ¼ teaspoon cornstarch dissolved in 1 cup of water. Heating  this mixture (a microwave works great) will help to dissolve the cornstarch. Cool to room temperature before using.
•   2 teaspoons of your saliva, divided (it is recommended that you rinse your mouth with water before collecting the saliva)
•   Iodine tincture (look for this in the first aid section of a pharmacy or grocery store; if you can’t find it, ask)
•   3 small clear glasses

PROTOCOL:

1.   Label the glasses 1 – 3. Add as follows:
a.   Glass #1: 1 tablespoon water + 1 teaspoon saliva
b.   Glass #2: 1 tablespoon cooled cornstarch mixture
c.   Glass #3: 1 tablespoon cooled cornstarch mixture plus your teaspoon of saliva. Mix well.

2.   Allow the three glasses to sit at least thirty (30) minutes.

3.   Add a few drops of the iodine tincture to each glass. Observe the color in each glass and record your results in Table 2 below.

4.   Answer the questions in the questions section that follows.


TABLE 2.

Glass Contents   Color after adding iodine
#1: Water + saliva   
#2: Cornstarch solution   
#3: Cornstarch solution + saliva   

QUESTIONS:

1.   What digestive enzyme is present in the saliva?
Salivary amylase

2.   What was the purpose of including the water + saliva glass?


3.   Compare the contents (not the color) of glass #2 to glass #3 after they both sat for thirty minutes. In other words, how is each of these changing chemically?  What explains this result?


4.   Could your body absorb the contents of glass #3 at this point? Explain your answer.


5.   If you boiled the saliva before adding it to glasses #1 and #3, would you expect either, both or neither of your results to change?  Explain.