Name: Date: Period: CSI: SPRING GROVE Due to your excellent background in biochemistry, you have been hired by Dr. Oliver Border of the Lancaster County Medical Examiner s Office to clear up a situation. During some confusion with previous laboratory technicians, samples of stomach contents from 5 murder victims have been mixed up! Since these specimens will serve as evidence in pending murder trials, it is essential that this mistake be corrected. The only information that you have about these murder victims is their last meal. Hopefully your knowledge of biochemistry will enable you to fill in the gaps and you will be able to match different stomach contents samples with their owners. You should follow the procedures (found on pages 3-4) for identifying various organic molecules including carbohydrates (sugar and starch), lipids, and proteins. Information about the last meals of the 5 victims is as follows: Name of Victim Last Meal Predict the type(s) of macromolecules found in the last meal Wendell Sputz A bag of jelly beans and a baked potato Margaret Little A bag of Skittles and iced tea U.R. Downs Plain spaghetti Lucy Wunderchomper A Big Mac Value Meal supersized with an extra order of supersized fries and a shake Davis O Leary A very lean steak and a glass of water
Set up the experiment to test the five stomach contents samples using all 4 tests. The stomach contents have already been labeled 1-5. Record your results in Table 3-1 and analyze your results to determine which stomach contents belong to each murder victim. Put your conclusions in Table 3-2. Materials Safety goggles Five test tubes Test tube rack Test tube holder Benedict s solution Gram s Iodine Biuret Reagent Spot plate Marker Hot plate 600 ml beaker Test tube brush Stomach contents of 5 victims
Identification Procedures Part A: Lipid Test 1. Look at each of the stomach contents. Decide which one looks greasy or has an oil layer and mark your results in Table 3-1. Part B: Carbohydrate Test Monosaccharides 1. Label each test tube with the name of the victim. 2. Fill the beaker with 200 ml of water and place the beaker on the hot plate. Turn the hot plate on high to heat up the water. 3. Place 20 drops of each of the stomach contents in the appropriately labeled test tube. 4. Place 10 drops of Benedict s solution in each test tube. 5. Mix gently. CAUTION: Benedict s solution is poisonous! If you get Benedict s solution on your skin then wash it off immediately with soapy water. Clean up any spills on the lab table with soapy water. 6. Place the test tubes in the hot water bath and heat for 5 minutes. 7. Remove the test tubes with a test tube holder after changes have occurred and place in the test tube rack until results are recorded. Benedict s solution turns from a clear blue to a cloudy orange/red or even green or yellow color in the presence of a monosaccharide. 8. Record results in Table 3-2. 9. Turn off the hot plate. 10. Clean the test tubes using a test tube brush and soapy water. 11. Pour out the water from the beaker and wash out the beaker. Part C: Carbohydrate Test Starch 1. Add 5 drops of each of the stomach contents into each of 5 wells on the spot plate. 2. Place 3 drops of Gram s Iodine into each well. 3. Record the results in Table 3-2. Gram s Iodine will change from brown to a dark purple/black color in the presence of starch. 4. Clean the spot plat using soapy water. Rinse well and dry off the spot plate.
Part D: Protein Test 1. Label each test tube with the name of the victim. 2. Place 20 drops of each of the stomach contents in each of the appropriately labeled test tubes. 3. Add 5 drops of Biuret reagent to each test tube. 4. Record the results in Table 3-2. Look for a color change. A positive result will be a purple color. 5. Clean the test tubes with the test tube brush and soapy water. Rinse well and turn the test tubes upside down to dry.
List the macromolecules found in each victim s stomach contents. Your choices are: Carbs Sugar, Carbs Starch, Protein, Lipids Table 3-2 Name of Victim Last Meal Macromolecules in the Stomach Contents Number of Stomach Contents Wendell Sputz Margaret Little A bag of jelly beans and a baked potato A bag of Skittles and iced tea U.R. Downs Lucy Wunderchomper Davis O Leary Plain spaghetti A Big Mac Value Meal supersized with an extra order of supersized fries and a shake A very lean steak and a glass of water Conclusion: Type or write a letter to Dr. Oliver Border analyzing your data and stating your conclusions. For example: U.R. Downs tested positive for only starch because he ate plain spaghetti, which is high in starch. Therefore, U.R. Downs stomach contents are #2. Dr. Oliver Border Lancaster County Coronor s Office 555 N. Duke St. Lancaster, PA 17601 November 2, 2010 Dear Dr. Border, Your letter should include: An introduction that includes why you were hired. The results of the tests and explanation of the results. List the errors that may have occurred, how they might have affected your results, and what you would do to minimize those errors in the future. Two data tables. A brief conclusion that thanks Dr. Border for his business. Sincerely,