In this activity you will observe the interaction of an enzyme and its substrate
ID: 101152 • Letter: I
Question
In this activity you will observe the interaction of an enzyme and its substrate by examining the effects of the lactase enzyme on the milk sugar lactose using glucose indicator strips. 1) Do you think the milk will test positive for glucose prior to addition of lactase? How about after lactase is added? Fill out the table with your predictions for the different liquids indicating whether you anticipate glucose will be present or absent in each solution. 2) What do you predict will happen if the enzyme lactase comes into contact with a sugar other than lactose, such as sucrose? Explain. Procedure: 1. Grind a single lactase tablet into a fine powder using a mortar and pestle Set this aside. 2. Obtain 6 test tubes. 3. Label your test tubes as follows a. Milk b. Milk + Lactase c. Almond Milk d. Almond Milk + Lactase e. Lactose Free Milk f. Lactose Free Milk + Lactase 4. Add -5ml of the appropriate liquid to each test tube according to the labels. Be careful not to contaminate the samples with different liquids, as this will skew the results. 5. Add a small amount of the powdered lactase to each of the tubes that read "+ lactase". Gently swirl the tubes to distribute the enzyme. 6. Wait 5-10 minutes for the reaction to occur. In the meantime, fill in the chart, indicating which tubes you predict will test positive for glucose. 7. Test each solution with a glucose strip (one per tube). Dip the strip into the solution and then let it sit for 5-10 minutes. Note any color change in the chart (a transition from yellow to green indicates glucose is present in the solution).Explanation / Answer
Lactase is essential to the complete digestion of whole milk; it breaks down lactose, a sugar which gives milk its sweetness. It is a glycoside hydrolase involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers.
If you consume lactose-free milk, because the lactose has already been digested into glucose and galactose, you don’t need to be able to produce the lactase enzyme to digest the milk. Instead, your intestinal tract can absorb the smaller sugars directly into the bloodstream, preventing intestinal symptoms associated with lactose intolerance. As such, lactose-free milk and other lactose-free dairy products cause no symptoms in lactose intolerant individuals.
To react lactose, manufacturers add small amounts of the enzyme lactase to milk, explains OrganicMeadow.com, a producer of lactose-free milk. The lactase splits lactose into its constituent components, which are two sugars called glucose and galactose.
Solution Prediction Results Milk negative Glucose absent Milk + lactase positive Glucose present Almond milk negative glucose absent,cane sugar present Almond milk + lactase negative glucose absent Lactose free milk posituve gluoce present Lactose free milk + lactose positive glucose present