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7 years ago
Activity 1

1.  What was the purpose of tubes #1 and #2?

2. What can you conclude from tubes #3 and #4?

3.  What do tubes #4, #6, and # 7 tell you about amylase activity and pH levels?

4. What is the optimal pH for amylase activity?

5. Does amylase work a pH levels other than the optimal pH?

6. What is the end-product of starch digestion?

7. In which tubes did you detect the presence of maltose at the end of the experiment?

8.  Why wasn't maltose present in the other tubes?

9.  Salivary amylase would be greatly deactivated in the stomach.  Suggest a reason why, based on what you have learned in this activity.
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7 years ago
Tubes 2, 6, and 7 showed the effect of pH on amylase activity. The results of this experiment indicate that the activity maximum of amylase is at pH 7.0, whereas pH 2.0 and pH 9.0 demonstrated very little activity. In this experiment, pH 7.0 showed the highest level of amylase activity. Tube 3 showed that amylase did not contain maltose contamination. Tubes 3, 4, and 5 showed that water had no starch or maltose contamination. Tube 3 directly showed that water did not have maltose or starch contamination. Tube 4 was a starch control (with the same water) that showed no maltose, and tube 5 was a maltose control (also with water) that showed no starch. If control tubes 3, 4, or 5 were not done, then what is perceived as digestion might really be starch or maltose contamination. Saliva would not be active in the stomach because the stomach pH is too low. Boiling inactivates, or denatures, enzymes.
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wrote...
7 years ago
Activity 1:

1. what was the purpose of tubes #1 and #2
Acts as controls, demonstrated the differences between starch and amylase.
2.what can you conclude from tubes #3 and #4
boiling alters the fluid inside test tube 3.  Boiling denatures enzymes
3.What do tubes 4,6 and 7 tell you about amylase activity and pH levels?
Amylase is affected differently by different pH levels.  Amylase is most affective in a pH of 7.
4. What is the optimal pH for amylase activity?
            The optimal pH for amylase activity is 7, although the enzyme is still active from, approximately pH 4.6 to 11. The stomach has a much more acidic environment, thus amylase activity in the stomach is greatly reduced. This also diminishes the time of starch digestion. Therefore, the amount of digestion of starch in the upper alimentary tract is insignificant in terms of quantity.
 
5. Does amylase work at pH levels other than the optimal pH?
            Amylase still exhibits activity at pH levels other than the optimum. Activity at these levels, however, is lower than at optimum. This is shown in test tubes 6 and 7, where pH is 2.0 and 9.0, respectively. These pH levels are far from the optimum, yet both test tubes tested positive in Benedict’s test. This confirms that maltose is present and that there indeed was amylase activity. Both test tubes also test positive for the IKI test, indicating that there is still starch left and that amylase activity was not maximal. This contrasts with test tube 4, which is at optimum pH and shows results in both Benedict’s (positive) and IKI test (negative) suggesting that there was complete starch digestion and maximal amylase activity.
 
6. What is the end product of starch digestion?
            Starch is broken down by amylase into maltose and dextrin. Dextrin can be further broken down into smaller starches and ultimately, maltose. Maltose can also be further broken down by the enzyme maltase into two glucose molecules for the use of cells. The presence of maltose is detected by Benedict’s Reagent in the exercise.
 
7. In which tubes did you detect the presence of maltose at the end of the experiment?
            Maltose is detected in the test tubes that tested positive for Benedict’s test: test tubes 4, 5, 6 and 7.
 
8. Why wasn’t maltose present in the other tubes?
            Maltose is absent in the test tubes that tested negative for Benedict’s test. These are test tubes 1, 2 and 3. The absence of maltose in these test tubes is due to different reasons. There was no maltose detected in test tube 1 because there was no amylase (enzyme) added. Amylase drives the digestion of starch into maltose molecules. With no enzyme present, no reaction occurred and no maltose products were obtained. Test tube 2 has no maltose because there was no starch (substrate) added. In this experiment, one needs a starch as the substrate for the enzyme to act upon. The final maltose products are derived from this starch substrate. With no substrate, one cannot expect the appearance of products. Test tube 3 has no maltose because of its incubation condition. The test tube was boiled before being incubated. Although the needed substrate and enzyme are present, the exposure to extreme heat had denatured the enzyme and effectively deactivated it.
 
9. Salivary amylase would be greatly deactivated in the stomach. Suggest a reason why, based on what you have learned in this activity.
            Due to the secretion of hydrochloric acid in the stomach, the gastric environment is highly acidic. This presents an unsuitable environment for amylase and thus, its activity is greatly reduced.

einna
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