REVIEW SHEET EXERCISE 8 Chemical and Physical Processes of Digestion 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? Salivary is most effective at a pH of 7.0 evolves to function in breaking down carbohydrates in the mouth

2.

How do you know that the amylase did not have any contaminating maltose? Used a negative control to detect if amylase was contaminated with maltose.

3.

What effect did boiling have on enzyme activity? It was denatured Why? Boiling destroys protein structure

4.

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

The following questions refer to Activity 2: Assessing Cellulose Digestion. 5.

Does amylase use cellulose as a substrate? Explain. No. Amylase is specific for starch and does not digest down cellulose

6.

Did freezing have an effect on the activity of amylase? Explain. Freezing does not change the structure of the enzyme and so it had no effect on the activity of

7.

Do you think that the bacterial suspension contained the enzyme cellulase (an enzyme that digests cellulose)? Why or why not? The bacterial suspension has cellulose, the enzyme that specifically digest cellulose.

8.

What is the substrate of peptidase? Explain, based upon your results. The substrate of peptidase is a protein and in the simulations it was a synthetic protein called BAPNA.

Protein Digestion by Pepsin The following questions refer to Activity 3: Assessing Protein Digestion by Pepsin. 10. At which pH did you see the highest activity of pepsin? 2.0 11. How does this correlate to the location of pepsin in the body? It correlates good with the gastric environment 12. What effect did boiling have on pepsin? Boiling denatures the enzyme 13. Was there any digested BAPNA contaminating the pepsin or deionized (DI) water? How can you tell? No digested BAPNA was found with pepsin or with deionized water; there was a negative spectrophotomer result 14. What is the substrate in this experiment? BAPNA 15. What is the usual substrate for pepsin, and what subunits are formed with pepsin activity? usual substrate is protein, the subunits are amino acids

16. What was the effect of decreasing the incubation time on the optical density results? Decreasing incubation time causes decreased optical density 17. What effect would decreased incubation temperature have on pepsin activity? Why? Reduced opyical density; decreased rate of enzymatic 18. What was the significance of using 37°C for the incubation? Because 37 C is body temperature 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. 19. Describe the activity of lipase with and without the addition of bile salts. Refer to Chart 4 for pH values. Lipase was more effective in the presence of bile salts 20. Is the activity of bile a chemical or a physical process? Explain. physical process, because it breaks up the fat 21. What pH resulted in the maximum pancreatic lipase activity? 7.0 22. How does this optimal pH correlate to the enzyme’s location in the body? It correlates with the duodenum 23. Explain whether or not we can determine fat hydrolysis in tube 5. Why or why not? The fat hydrolysis in tube 5 is determined because we know the pH and I did not see a reduction in pH 24. What is the substrate in this experiment? fats or vegetable oils 25. What subunits does lipase form? fatty acids Physical Process: Mechanisms of Food Propulsion and Mixing The following questions refer to Activity 5: Studying Mechanisms of Food Propulsion and Mixing: Deglutition (Swallowing). 26. Explain the significance of the movement of the tongue during swallowing. prevent water from entering the airway. 27. Describe three events that occur during the pharyngeal-esophageal phase of deglutition. Mouth, nasopharynx, and larynx are blocked; upper esophageal sphincter relaxes to open esophagus; food moves through esophagus by pressure gradients created by peristalsis. 28. What was the time interval that you recorded between the first and second sound? I do not have a stethoscope nor did I have a lab partner to complete this question.