lease help still not receive kit;Attachment Preview;Lab_4_Answer_Sheet.doc Download Attachment;Your Full Name;UMUC Biology 102/103;Lab 4: Enzymes;INSTRUCTIONS;On your own and without assistance, complete this Lab 4 Answer Sheet;electronically and submit it via the Assignments Folder by the date listed in the Course;Schedule (under Syllabus).;To conduct your laboratory exercises, use the Laboratory Manual located under;Course Content. Read the introduction and the directions for each exercise/experiment;carefully before completing the exercises/experiments and answering the questions.;Save your Lab 4 Answer Sheet in the following format: LastName_Lab4 (e.g.;Smith_Lab4).;You should submit your document as a Word (.doc or.docx) or Rich Text Format;(.rtf) file for best compatibility.;Pre-Lab Questions;1. How could you test to see if an enzyme was completely saturated during an;experiment?;2. List three conditions that would alter the activity of an enzyme. Be specific with;your explanation.;3. Take a look around your house and identify household products that work by;means of an enzyme. Name the products, and indicate how you know they work;with an enzyme.;Experiment 1: Enzymes in Food;This experiment tests for the presence of amylase in food by using Iodine-Potassium;Iodide, IKI. IKI is a color indicator used to detect starch. This indicator turns dark purple;or black in color when in the presence of starch. Therefore, if the IKI solution turns to a;dark purple or black color during the experiment, one can determine that amylase is not;present (because presence of amylase would break down the starch molecules, and the;IKI would not change color).;Materials;(1) 2 oz. Bottle (Empty);*2 Food Products (e.g., ginger root;(1) 100 mL Graduated Cylinder;apple, potato, etc.);30 mL Iodine-Potassium Iodide, IKI *Kitchen Knife;Permanent Marker;*Paper Towel;Ruler;*Saliva Sample;2 Spray Lids;*Tap Water;30 mL Starch (liquid);*Cutting Board;*You Must Provide;Procedure;1. Remove the cap from the starch solution. Attach the spray lid to the starch;solution.;2. Rinse out the empty two ounce bottle with tap water. Use the 100 mL graduated;cylinder to measure and pour 30 mL of IKI into the empty two ounce bottle.;Attach the remaining spray lid to the bottle.;3. Set up a positive control for this experiment by spraying a paper towel with the;starch solution. Allow the starch to dry for approximately one hour (this time;interval may vary by location).;4. In the mean time, set up a negative control for this experiment. Use your;knowledge of the scientific method and experimental controls to establish this;component (hint: what should happen when IKI solution contacts something that;does not contain starch?) Identify your negative control in Table 1.;Note: Be sure to space the positive and negative controls apart from each other;to prevent cross-contamination.;5. When the starch solution has dried, test your positive and negative controls. This;step establishes a baseline color scale for you to evaluate the starch;concentration of the food products you will;test in Steps 7 - 11. Record your results in;Table 1.;6. Select two food items from your kitchen;cabinet or refrigerator.;7. Obtain a kitchen knife and a cutting board.;Carefully cut your selected food items to;create a fresh surface.;8. Gently rub the fresh/exposed area of the;food items on the dry, starch-sprayed paper;towel back and forth 10 - 15 times. Label;where each specimen was rubbed on the;Figure 3: Sample set-up.;paper towel with a permanent marker;(Figure 3).;9. Wash your hands with soap and water.;10. Take your finger and place it on your tongue to transfer some saliva to your;finger. Then, rub your moistened finger saliva into the paper towel. Repeat this;step until you are able to adequately moisten the paper towel.;Note: You should always wash your hands before touching your tongue!;Alternatively, if you do not wish to put your hands in your mouth, you may also;provide a saliva sample by spitting in a separate bowl and rubbing the paper;towel in the saliva. Be sure not to spit on the paper towel directly as you may;unintentionally cross-contaminate your samples.;11. Wait five minutes.;12. Hold the IKI spray bottle 25 - 30 cm away from the paper towel, and mist with the;IKI solution.;13. The reaction will be complete after approximately 60 seconds. Observe where;color develops, and consider what these results indicate. Record your results in;Table 1.;Table 1: Substance vs. Starch Presence;Substance;Positive Control: Starch;Negative Control: Student Must;Select;Food Product;Food Product;Saliva;Resulting Color;Presence of Starch?;Post-Lab Questions;1. What were your controls for this experiment? What did they demonstrate? Why was;saliva included in this experiment?;2. What is the function of amylase? What does amylase do to starch?;3. Which of the foods that you tested contained amylase? Which did not? What;experimental evidence supports your claim?;4. Saliva does not contain amylase until babies are two months old. How could this;affect an infants digestive requirements?;5. There is another digestive enzyme (other than salivary amylase) that is secreted by;the salivary glands. Research to determine what this enzyme is called. What;substrate does it act on? Where in the body does it become activated, and why?;6. Digestive enzymes in the gut include proteases, which digest proteins. Why dont;these enzymes digest the stomach and small intestine, which are partially composed;of protein?;Experiment 2: Effect of Temperature on;Enzyme Activity;Yeast cells contain catalase, an enzyme which;helps convert hydrogen peroxide to water;and oxygen. This enzyme is very significant as;hydrogen peroxide can be toxic to cells if allowed;Figure 4: Catalase catalyzes the;decomposition of hydrogen peroxide;to water and oxygen.;to accumulate. The effect of catalase can be seen when yeast is combined with;hydrogen peroxide (Catalase: 2 H2O2 2 H2O + O2).;In this lab you will examine the effects of temperature on enzyme (catalase) activity;based on the amount of oxygen produced. Note, be sure to remain observant for;effervescence when analyzing your results.;Materials;(2) 250 mL Beakers;3 Balloons;30 mL 3% Hydrogen Peroxide;H2O2;Measuring Spoon;Permanent Marker;Ruler;20 cm String;3 Test Tubes (Glass);Test Tube Rack;Thermometer;Yeast Packet;*Hot Water Bath;*Stopwatch;*You Must Provide;Procedure;1. Use a permanent marker to label test tubes 1, 2, and 3. Place them in the test;tube rack.;2. Fill each tube with 10 mL hydrogen peroxide. Then, keep one of the test tubes in;the test tube rack, but transfer the two additional test tubes to two separate 250;mL beakers.;3. Find one of the balloons, and the piece of string. Wrap the string around the;uninflated balloon and measure the length of the string with the ruler. Record the;measurement in Table 2.;4. Create a hot water bath by performing the following steps;a. Determine if you will use a stovetop or microwave to heat the water. Use;the 100 mL graduated cylinder to measure and pour approximately 200;mL of water into a small pot or microwave-safe bowl (you will have to;measure this volume in two separate allocations).;b. If using a stovetop, obtain a small pot and proceed to Step 4c. If using a;microwave, obtain a microwave-safe bowl and proceed to Step 4e.;c. If using a stove, place a small pot on the stove and turn the stove on to a;medium heat setting.;d. Carefully monitor the water in the pot until it comes to a soft boil;(approximately 100 C). Use the thermometer provided in your lab kit to;verify the water temperature. Turn the stove off when the water begins to;boil. Immediately proceed to Step 5.;CAUTION: Be sure to turn the stove off after creating the hot water bath.;Monitor the heating water at all times, and never handle a hot pan without;appropriate pot holders.;e. If using a microwave, place the microwave-safe bowl in the microwave;and heat the water in 30 second increments until the temperature of the;water is approximately 100 C. Use the thermometer provided in your lab;kit to verify the water temperature. Wait approximately one minute before;proceeding to Step 5.;5. Place Tube 1 in the refrigerator. Leave Tube 2 at room temperature, and place;Tube 3 in the hot water bath.;Important Note: The water should be at approximately 85 C when you place;Tube 3 in it. Verify the temperature with the thermometer to ensure the water is;not too hot! Temperatures which exceed approximately 85 C may denature the;hydrogen peroxide.;6. Record the temperatures of each condition in Table 2. Be sure to provide the;thermometer with sufficient time in between each environment to avoid obscuring;the temperature readings.;7. Let the tubes sit for 15 minutes.;8. During the 15 minutes prepare the balloons with yeast by adding tsp. of yeast;each balloon. Make sure all the yeast gets settled to the bulb of the balloon and;not caught in the neck. Be sure not spill yeast while handling the balloons.;9. Carefully stretch the neck of the balloon to help ensure it does not rip when;stretched over the opening of the test tube.;10. Attach the neck of a balloon you prepared in step 8 to the top of Tube 2 (the;room temperature test tube) making sure to not let the yeast spill into the test;tube yet. Once the balloon is securely attached to the test tube lift the balloon;and allow the yeast to enter the test tube. Tap the bulb of the balloon to ensure;all the yeast falls into the tube.;11. As quickly and carefully as possible remove the Tube 1 (cold) from the;refrigerator and repeat steps 9 - 10 with Tube 1 using a balloon you prepared in;step 8.;12. As quickly and carefully as possible remove Tube 3 (hot) from the hot water bath;and repeat steps 9 - 10 with Tube 3 using a balloon you prepared in step 8.;13. Swirl each tube to mix, and wait 30 seconds.;14. Wrap the string around the center of each balloon to measure the circumference.;Measure the length of string with a ruler. Record your measurements in Table 2.;Table 2: Balloon Circumference vs. Temperature;Tube;Temperature;(C);Balloon Circumference;(Uninflated, cm);Balloon Circumference;(Final, cm);1 - (Cold);2 - (RT);3 - (Hot);Post-Lab Questions;1. What reaction is being catalyzed in this experiment?;2. What is the enzyme in this experiment? What is the substrate?;3. What is the independent variable in this experiment? What is the dependent;variable?;4. How does the temperature affect enzyme function? Use evidence from your data to;support your answer.;5. Draw a graph of balloon diameter vs. temperature. What is the correlation?;6. Is there a negative control in this experiment? If yes, identify the control. If no;suggest how you could revise the experiment to include a negative control.;7. In general, how would an increase in substrate alter enzyme activity? Draw a graph;to illustrate this relationship.;8. Design an experiment to determine the optimal temperature for enzyme function;complete with controls. Where would you find the enzymes for this experiment?;What substrate would you use?
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