Biology 05-3: Visualization of Digestive Enzymes

Large proteins consumed in food sources are broken down by digestive enzymes to yield smaller protein chains. These smaller protein fragments may be further broken down into amino acid monomers, which can be used for various biological processes by cells. In this part of the lab, we will examine the breakdown of proteins by found in certain fruits, such as pineapple. Pineapple contains the catalytic protein enzyme called bromelain. Gelatin is a commonly available protein product that is derived from the protein collagen, a major component of connective tissues in animals. Gelatin is usually sold as a powder. When the powder is rehydrated and cooled, some of the gelatin will form long, helical protein chains and form a semi-solid gel.

Materials

• Two packets of gelatin (commonly sold as a dessert in grocery stores)

• 2 tablespoons diced fresh pineapple, divided

• 3 clear, heat-resistant containers (recycled jars work well)

• Water

• Means to cook some of the pineapple (microwave, stovetop, etc.)

• Refrigerator to cool and set gelatin

• 3 coins of same type (quarters, pennies, etc.)

• Camera

Methods

1. Before beginning the experiment, fill out the hypothesis and prediction sections in your datasheet.

2. Measure out a total of two tablespoons of pineapple. Cook one tablespoon of the pineapple (mi-crowave or stovetop) and allow to cool to room temperature. Leave the remaining tablespoon of pineapple at room temperature.
3. Label the containers: ‘cooked,’ ‘control,’ and ‘fresh.’

4. Mix gelatin powder with water (warm or hot) according to the package instructions.

5. Equally divide the prepared gelatin solution between the three clear containers.

6. Add the one tablespoon of cooked, cooled pineapple to the container labeled ‘cooked.’

7. Add one tablespoon of fresh pineapple to the container labeled ‘fresh.’

8. Do not add pineapple to the container marked ‘control.

9. Put all three containers in the refrigerator for several hours.

10. Remove the containers from the fridge and inspect the gelatin. Has gel formed in any of the containers? Place a coin on top of each and gently shake the container in a side-to-side motion.
11. Document your results with your camera. Record your observations and answer the questions in the datasheet.

 

Question: Will the addition of pineapple affect the formation of a semi-solid gelatin?