Gelatin and Enzyme Lab

Enzymes are present in our body and many substances. Enzymes are substances that speed up chemical reactions. Each enzyme operates best at a particular pH and temperature. Substances on which enzymes act are called substrates. Many enzymes are named for their substrate they work with. For example, protease is an enzyme that helps break down proteins. In this lab, you will investigate the effectiveness of laundry detergents that may or may not contain enzymes.

PURPOSE

The purpose of this activity is to observe the effectiveness of some common detergents on breaking down protein using gelatin.

MATERIALS

·  1 petri dish containing gelatin

·  1 marking pen

·  1 plastic straw section

·  1 metric ruler

·  1 toothpick

·  Access to a variety of detergent solutions each with its own pipette

·  Access to distilled water with a pipette included for the control well

PROCEDURE – DAY 1

  1. Obtain a gelatin filled petri dish. Identify the dish on the bottom by writing (near the edge and in small letters) your name and class.
  2. Place the dish right-side up and using the plastic soda straw section, cut 7 wells in the plate.
  3. Remove the plugs of gelatin with a toothpick. Take care not to tear the layer of gelatin. Number the wells on the bottom of your dish.
  4. Measure the diameter of the wells (in mm) by placing the dish on a metric ruler. Record on Table 1 as "initial diameter".
  5. Record the 6 different detergent solutions on Table 1.
  6. Use only the dropper that is in each solution. Do not mix droppers from tube to tube. Carefully "load" each of the wells with these detergents. To load the wells, place the pipette into the well and gently dispense just enough liquid to fill the well. Load distilled water into well #7. This will be your control.
  7. Be sure the numbered well corresponds with the number of the detergent listed on your data sheet.
  8. Do not drop any liquid onto the surface of the gelatin! This can ruin the results of this experiment. If you do - note the location of the drop by drawing a picture in your notebook.
  9. Let the dish sit overnight in a cool place. Do not disturb the dish during that time.

DAY 2

1.  Observe the wells in the petri dish. Record any physical change in the gelatin that you see around some or all of the wells.

2.  Measure the diameter of each well in mm. The diameter of a well is the distance from solid gelatin© on one side to the solid gelatin© on the other side. Record this measurement on Table 1 as the "final diameter."

3.  Answer questions at end of lab.

TABLE 1

Well # / Detergent Name / Initial Diameter (mm) / Final Diameter (mm)
1
2
3
4
5
6
7

QUESTIONS

1.  Was there any change in the gelatin around well #7? Why or Why not?

  1. Which products increased the size of the well diameter?
  1. What ingredient in the detergents is responsible for the breakdown of the gelatin?
  1. Which detergent would you choose to remove an egg stain?
  1. Why do you think that some laundry is washed in hot water and some in cold water? What possible effects could using the wrong temperature of water have?
  1. What effect does pH have on the activity of enzymes? Think back to the overhead I showed you about various pHs.