17 Digestion - Student.pdf - haspi

Name: __________________________________________ Date: ___________ Period: _________
PART C: Fat Digestion
In part C the corn oil represents the lipid polymer, and lipase is the enzyme responsible for breaking
the lipid down. A change in pH will demonstrate that the enzyme is active. The soap works similarly
to bile, and will break up the oil so lipase can work more easily.
1. Using a pencil, label wells 1-3 on the spot plate.
2. Add 10 drops of water to wells 1-3.
3. Add 3 drops of Corn oil to wells 1-3.
4. Use separate stirring sticks to mix each well thoroughly.
5. Use the forceps to dip a separate pH strip into each of the wells 1-3. Compare the color
change of each strip to the pH strip chart to determine the pH of the mixture in each well.
Record your results in Data Table 3.
6. Add 5 drops of lipase to well 2 and 3.
7. Add 2 drops of liquid soap to well 3.
8. Re-stir the mixture in each well, and allow them to sit for 20 minutes.
9. Retest the pH and record your results in Data Table 3.
10. Record your observations of each of the mixtures in Data Table 3.
11. Rinse out your spot plate and dry it off with a paper towel.
PART D: Testing for Macromolecules in Food
In part D you will be performing portions of the tests from parts A-C to determine whether your food
sample contains proteins, carbohydrates, and/or lipids.
1. Choose a food item that is easily mixed with water.
2. In a beaker, mix a small amount of your food sample in 10 ml of water. If the food sample is
solid it will need to be thoroughly smashed.
3. Using a pencil, label wells 1-5 on the spot plate.
4. Add 5 drops of your food sample mixture to wells 1-5. Well 1 will act as the control.
5. Use the forceps to dip a separate pH strip into each of the wells. Compare the color change of
each strip to the pH strip chart to determine the pH of the mixture in each well. Record your
results in Data Table 4.
6. Test your food sample for protein by adding 5 drops of pepsin and 5 drops of HCl to well 2.
7. Allow well 2 to sit for 5-7 minutes, then add 2 drops of Biuret. The mixture will turn pink if
protein is present. Retest the pH of well 2. Record the results in Data Table 4.
8. Test your food sample for carbohydrates by adding 5 drops of amylase to well 4.
9. Allow well 3 and 4 to sit for 5-7 minutes then retest the pH of wells 3 and 4.
10. Add 1 drop of potassium iodine to well 3 and 4. The mixture will turn blue-black in the
presence of starch. Record the results in Data Table 4.
11. Test your food sample for lipids by adding 5 drops of lipase and 2 drops of soap to well 5.
12. Allow well 5 to sit for 20 minutes, then retest the pH of well 5, and record the results in Data
Table 4.
Adapted from Neo/Sci Food Digestion Lab Activity 2011 238