Science Fair Planning and Approval Sheet Tantasqua Regional High School

This sheet must be completed and submitted to Mr. Jefferson by MONDAY, September 30th, 2013.

Project Title: Lactase Specificity

Name(s): Margaret Krause

Date: 9/26/13

1. What is the question that your experiment is designed to answer?

Will lactase break down any sugars other than lactose?

2. What is your hypothesis (predicted answer) to the question that you are investigating?

If lactase is specific to lactose, then it will not break down other sugars.

3. Why did you predict this answer? (What background research have you collected?)

There are some enzymes that act as a catalyst to several substances with similar bonds and structures. However, most enzymes have absolute specificity, which means they act on only one substrate. Most sugars and their corresponding enzymes have this relationship; for example, sucrase and sucrose, or maltase and maltose.

4. What are the controlled variables in your experiment? (Controlled variables are the variables that you will hold constant.)  Corn (fructose) syrup and water solution: 2 mL fructose syrup to 1 mL water  Sucrose and water solution: 5 grams sucrose (1 teaspoon) to 100 mL water  Skim milk (contains lactose) and water solution: 2 mL skim milk to 1 mL water  Dextrose and water solution: 5 grams dextrose to 100 mL water  Aspartame and water solution: 5 grams aspartame to 100 mL water  Enzyme used (lactase)  Amount of water used per control solution (1 mL for liquids; 100 mL for powders)  Amount of the enzyme that is used (exactly 1 tablet)  Amount of skim milk used (2 mL)  Amount of fructose syrup used (2 mL)  Amount of sucrose used (5 grams)  Amount of dextrose used (5 grams)  Amount of Aspartame used (5 grams)  Amount of enzyme solution (lactase pill and 200 mL of water) used with each test tube solution (2 mL per solution)  Amount of time each combined solution is left to sit before the glucose test strip is applied (30 seconds)

5. What is the independent variable? (The independent variable is the variable that you will be manipulating or changing.) The sugars

6. What is the dependent variable? (The dependent variable is the variable that you will be measuring or observing in response to the change in the dependent variable.) The presence of glucose

7. List the materials that you will need to conduct this experiment.  10 test tubes  1 100 mL graduated cylinder  2 10 mL graduated cylinders  Test tube rack  4 400 milliliter beakers  Glucose test strips  Lactase tablets  Water  Skim Milk  Sucrose  Fructose  Dextrose (Pure Via®; also contains Stevia Extract, Cellulose Powder, Natural Flavors)  Aspartame (Sweet ‘N Low®)  Stirring Rod  Pencil  Data sheet  Labels

8. Write the step-by-step procedure that you will use to conduct your experiment. (Attach another piece of paper if needed.) 1. Label each test tube with the number corresponding to its solution. 2. Label each beaker with the number corresponding to its solution. 3. Prepare the Enzyme Solution in a 400 mL beaker: One lactase tablet to 200 mL of water. 4. Stir until tablet dissolves. 5. Prepare the sucrose solution in a 400 mL beaker: 5 grams of sucrose to 100 mL of water. 6. Prepare the fructose syrup solution in two separate 10 mL graduated cylinders: a) 2 mL fructose syrup in one graduated cylinder b) 1 mL water in the other graduated cylinder c) Combine the separate ingredients in test tube 3. d) Repeat steps 6a and 6b. e) Combine the separate ingredients in test tube 4. 7. Prepare the dextrose solution in a 400 mL graduated cylinder: 5 grams dextrose to 100 mL water. 8. Prepare aspartame solution in a 400 mL graduated cylinder: 5 grams aspartame to 100 mL water. 9. Prepare skim milk solution in two separate 10 mL graduated cylinders: a) 2 mL skim milk in one graduates cylinder. b) 1 mL water in another graduated cylinder. c) Combine the separate ingredients in test tube 9. d) Repeat steps 9a and 9b. e) Combine the separate ingredients in test tube 10. 10. Transfer 2 mL each of sucrose solution to test tubes 1 and 2. 11. Transfer 2 mL each of dextrose solution to test tubes 5 and 6. 12. Transfer 2 mL each of aspartame solution to test tubes 7 and 8. 13. Add 1 mL of enzyme solution to test tube 2. 14. Add 1 mL of enzyme solution to test tube 4. 15. Add 1 mL of enzyme solution to test tube 6. 16. Add 1 mL of enzyme solution to test tube 8. 17. Add 1 mL of enzyme solution to test tube 10. 18. Using the glucose test strips, test each test tube for the presence of glucose. 19. Record results. 20. Repeat the procedure. Please check off YES or NO for each of the following questions. Yes No My experiment will not physically or psychologically harm people. X My experiment will not physically or psychologically harm animals. X My experiment does not involve the use of explosives, flammable chemicals, or X toxic chemicals. I can get all of the materials needed to carry out my experiment. X I have enough time to conduct my experiment. X

If you answered NO to any of the above questions, please provide an explanation below.

TEST TUBE LABELS:

Test tube 1: sucrose solution Test tube 2: sucrose solution and enzyme solution Test tube 3: fructose solution Test tube 4: fructose solution and enzyme solution Test tube 5: dextrose solution Test tube 6: dextrose solution and enzyme solution Test tube 7: aspartame solution Test tube 8: aspartame solution and enzyme solution Test tube 9: skim milk solution Test tube 10: skim milk and enzyme solution

BEAKER LABELS:

Beaker 1: enzyme solution Beaker 2: sucrose solution Beaker 3: dextrose solution Beaker 4: aspartame solution