Review Sheet 39b

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R E V I E W version 8

S H E E T
EXERCISE

39 B

NAME ____________________________________ LAB TIME/DATE ________________________

Chemical and Physical Processes of Digestion: Computer Simulation

Carbohydrate Digestion
The following questions refer to Activity 1: Assessing Starch Digestion by Salivary Amylase. 1. At what pH did you see the highest activity of salivary amylase?

7.0

Why?

because that is when the salivary is most effective and it breaks down carbohydrates
2. How do you know that the amylase did not have any contaminating maltose?

because the sample didn't change color.

Negative sugar/IKI test. No change from original blue bright color.

We used a negative control to see if there is any amylase in the maltose
3. What effect did boiling have on enzyme activity? Why?

Boiling denatured the enzyme because it destroys the structure of the protein.

4. Describe the substrate and the subunit product of amylase.
The substrate is starch the subunit is reducing sugar.

The following questions refer to Activity 2: Assessing Cellulose Digestion. 5. Does amylase use cellulose as a substrate? Explain.

No because amylase only works on starch and wont digest cellulose.
6. Did freezing have an effect on the activity of amylase? Explain. Freezing does not change the structure of the enzyme so it doesn’t have effect on the activity. 7. Do you think that the bacterial suspension contained the enzyme cellulase (an enzyme that digests cellulose)? Why or why not? Yes I think the bacteria contained cellulose because it specifically digests cellulose.

8. What is the substrate of peptidase? Explain, based upon your results. The substrate is a synthetic protein called APNA.

PEx-141

PEx-142

Review Sheet 39B

Protein Digestion by Pepsin
The following questions refer to Activity 3: Assessing Protein Digestion by Pepsin. 9. At which pH did you see the highest activity of pepsin? body?

2

How does this correlate to the location of pepsin in the

10. What effect did boiling have on pepsin?

boiling denatures and inactivates the enzyme

11. Was there any digested BAPNA contaminating the pepsin or deionized (DI) water? How can you tell?

12. What is the substrate in this experiment? What is the usual substrate for pepsin, and what subunits are formed with pepsin activity?

13. What was the effect of decreasing the incubation time on the optical density results?

14. What effect would decreased incubation temperature have on pepsin activity? Why?

15. What was the significance of using 37°C for the incubation?

Fat Digestion by Pancreatic Lipase and the Action of Bile
The following questions refer to Activity 4: Assessing Fat Digestion by Pancreatic Lipase and the Action of Bile. 16. Describe the activity of lipase with and without the addition of bile salts. Refer to Chart 4 for pH values.

17. Is the activity of bile a chemical or a physical process? Explain.

Review Sheet 39B

PEx-143

18. What pH resulted in the maximum pancreatic lipase activity? How does this optimal pH correlate to the enzyme’s location in the body?

19. Explain whether or not we can determine fat hydrolysis in tube 5. Why or why not?

20. What is the substrate in this experiment? What subunits does lipase form?

Physical Process: Mechanisms of Food Propulsion and Mixing
The following questions refer to Activity 5: Studying Mechanisms of Food Propulsion and Mixing: Deglutition (Swallowing). 21. Explain the significance of the movement of the tongue during swallowing.

22. Describe three events that occur during the pharyngeal-esophageal phase of deglutition.

23. What was the time interval that you recorded between the first and second sound?