PEX-08-01

Exercise 8: Chemical and Physical Processes of Digestion: Activity 1: Assessing Starch Digestion by Salivary Amylase Lab Report Pre-lab Quiz Results You scored 100% by answering 6 out of 6 questions correctly. 1. The substrate for amylase is You correctly answered: e. starch and carbohydrate. 2. Which of the following is true of enzymes? enzymes? You correctly answered: c. Their activity can be affected by temperature and pH. 3. The reagent IKI tests for the presence of You correctly answered: a. starch. 4. Which of the following is not  true  true of controls? You correctly answered: d. A negative result with a positive control is required to validate the test 5. Which of the following is an end product product of starch digestion? You correctly answered: e. maltose and glucose 6. Hydrolases are enzymes that break down large molecules into smaller smaller subunits through the addition of _____________. _____________. You correctly answered: b. water

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Experiment Results Predict Question: Predict Question: What effect do you think boiling and freezing will have on the activity of the amylase enzyme? Your answer : c. Boiling will decrease amylase activity and freezing will have no effect. Stop & Think Questions: Tube 2 appears to have the same amount of starch digested as tube 3 because You correctly answered: a. freezing had no effect on the enzyme. Experiment Data: Tube No. 1 2 3 4 5 6 7 8

Reagent 1 Amylase Amylase Amylase Amylase Starch Maltose Amylase Amylase

Reagent 2 Starch Starch Starch Water Water Water Starch Starch

Reagent 3 pH 7.0 pH 7.0 pH 7.0 pH 7.0 pH 7.0 pH 7.0 pH 2.0 pH 9.0

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Treatment Boiled Frozen None None None None None None

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Time 60 60 60 60 60 60 60 60

T em p . 37 37 37 37 37 37 37 37

IKI + + + +

Benedict's ++ ++ ++ + +

Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Tubes 3, 7, and 8 reveal that You correctly answered: d. amylase activity was highest at pH 7. 2. This activity includes a number of negative controls. Which tube indicates that the amylase solution was not contaminated with maltose? You correctly answered: b. tube 4 3. Which tubes indicate that that the deionized water did not contain contaminating starch or maltose? You correctly answered: c. tubes 4, 5, and 6 4. Explain where and why salivary amylase would be most active. active. You correctly answered: d. Salivary amylase would be most active in the mouth because pH 7 is where its peak activity is.

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Review Sheet Results 1. List the substrate and the subunit product of amylase. Your answer: The substrate of amylase is animal starch and the product is maltose and glucose. 2. What effect did boiling have on enzyme enzyme activity? Why? How well did the results this compare with your prediction? Your answer: The boiling denatured the enzyme and inactivated it as predicted. The freezing has no effect on the enzyme. 3. At what pH pH was the amylase activity the most active? Describe the significance of this result. Your answer: Amylase was most active at pH 7.0. This is significant because this is the same pH as the mouth. 4. Briefly describe the need for for controls and give an example used in this activity. Your answer: Controls are necessary to validate the results of the experiment. Tube #5 is an example where the enzyme that tests for contaminating glucose in the starch or the buffer is absent. 5. Describe the significance of using a 37°C incubation temperature to test test salivary amylase activity. Your answer: The 37°C 37°C incubation is significant signi ficant because it is the same temperature as body temperature so it should be ideal for the enzyme.

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