In this lab, I will study how digestion of carbohydrates, proteins, and fats occurs. I will define Key Terms that describe what will occur in the experiments; I will conduct an experiment for each Activity and provide all resulting Data as well as answer Questions from each Activity. I will then provide a short Summary for what I learned in each Activity.
Enzymes (p. 105) – Speed up chemical reactions in living things. Biological catalysts.
Catalysts (p. 105) - is any substance which makes a chemical reaction go faster, without itself being changed.
Hydrolases (p. 105) – Reaction with water. A chemical process in which a molecule is cleaved into two parts by the addition of a molecule of water. Substrates (p. 105) - the substance upon which an enzyme acts
Enzyme Assay (p. 106) - laboratory methods for measuring enzymatic activity. They are vital for the study of enzyme kinetics and enzyme inhibition.
Deglutition (p. 115) – The act or process of swallowing.
Activity 1: Assessing Starch Digestion by Salivary Amylase
Chart 1 – Salivary Amylase Digestion of Starch
AdditivesAmylase, StarchAmylase, Starch Amylase, DI Water DI Water, Starch
pH 7.0 bufferpH 7.0 bufferpH 7.0 buffer pH 7.0 buffer
Incubation Cond. Boil, Inc. 37 deg.C37 degrees C37 degrees C 37 degrees C
for 60 minutes
Chart 1 – Salivary Amylase Digestion of Starch (continued)
AdditivesDI Water, Maltose Amylase, Starch Amylase, Starch
pH 7.0 buffer pH 2.0 buffer pH 9.0 buffer
Incubation Cond. 37 degrees C 37 degrees C 37 degrees C
1-1: What do tubes 2, 6, and 7 reveal about pH and amylase activity? Hint: What variable was changed in the procedure?
The pH level was changed. Tube 2 had a pH of 7, tube 6 had a pH of 2 and tube 7 had a pH of 9. They all show how pH effects amylase activity.Tests 6 & 7 shows that the amylase was not being broke down because of the pH level differences. Test 2 shows that with a low pH there was a lot of activity.
1-2: Which pH buffer allowed the highest amylase activity? pH = ___7.0____
1-3: Which tube indicates that the amylase was not contaminated with maltose? Tube #___3____
1-4: Which tubes indicate that the deionized water did not contain contaminating starch or maltose? Tubes ___3___, __4____, __5____
1-5: If we left out control tubes 3,4, or 5, what objections could be raised to the statement: "Amylase digests starch to maltose"? (Hint: Think about the purity of the chemical solutions). In other words, what else might have happened other than digestion?)
If tubes 3, 4, or 5 were left out, an objection to the statement, “Amylase digests starch to maltose,” can be made that the enzyme maltose and starch would be polluted.
1-6: Would the amylase present in saliva be active in the stomach? Explain your answer (why or why not)? (Hint: think about pH.)
No. Amylase would not be active in the stomach because the pH level found in gastric acids is low, which will cause amylase to be defective.
1-7: What effect does boiling have on enzyme activity?
The activity rises until the temperature gets to high, then the enzyme will be inactivated.
In this Activity, I learned/observed that:
I learned the lower the PH level is then the more responsive the enzyme will react, and the higher the pH is the less active the enzyme will...