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Do not write on this – return to Mrs. Cardellini when you turn in your lab McMush Food Test – Biology Honors INTRODUCTION: All living things are composed of the same 4 basic organic compounds: carbohydrates (simple sugars and starches), proteins, lipids (fats, oils, waxes, and steroids), and nucleic acids (DNA and RNA). Many of these compounds, along with vitamins and other nutrients, provide your body with the energy needed to carry out life’s activities. These compounds are present in the plants and animals you use as food. To determine the presence of these substances, scientists use chemicals called indicators which react with the compound to produce a color change. The change is a result of the chemical reactions between the indicator and the specific molecular arrangement (structure) of the compound being tested. In this lab, you will test for specific compounds in food from McDonalds by using various indicators. If a color change is observed, the test is said to have a positive result, confirming the presence of a particular compound. Carbohydrates You know these as sugars and starches. Monosaccharides or simple sugars such as glucose and fructose (C6H12O6) function as an energy source in cells and are also used to build cell structures and other organic molecules within the cells. Disaccharides are composed of two monosaccharides joined together. Sucrose (table sugar) is a disaccharide composed of one glucose and one fructose molecule. Polysaccharides: These are long chains of monosaccharides bonded together. Plants store excess glucose in the form of starch, a polysaccharide composed of long chains of glucose. Starches can be found in potatoes, rice, wheat, corn, bananas, peas, beans, lentils, and other tubers, seeds and fruits of plants. Animals (and humans) store excess glucose in the form of glycogen in the liver and muscles. Between meals the liver breaks down glycogen to glucose and releases it into the blood stream to supply glucose to cells in need. Other important polysaccharides are cellulose and chitin. Cellulose makes up the cell wall of plants whereas chitin provides structure to fungi and the exoskeleton of arthropods. Lipids A lot of lipids function as long-term energy storage. One gram of fat stores more than twice as much energy as one gram of carbohydrates. Lipids are also an important component of the cell membrane in phospholipids. The fatty acid tails are hydrophobic (water repelling) while the phosphates are hydrophilic (water loving). Lipids consist of glycerol and fatty acid "tails". The fatty acid chains can be saturated, with all carbons saturated with hydrogen atoms forming a straight chain without double bonds. Unsaturated fatty acids contain double bonds within the carbon chain, which results in a bend of the chain. Proteins Proteins are complex, specialized molecules composed of carbon, oxygen, hydrogen, nitrogen and sometimes sulfur. The building blocks of proteins are amino acids. There are 20 different amino acids that combine to form polypeptides (proteins). Proteins have many important roles in organisms. Structural proteins such as collagen or elastin, provide support. Regulatory proteins such as enzymes control cell processes. Proteins also play an important part in the immune system (antibodies), oxygen transport (hemoglobin), movement (muscles) etc. PURPOSE: To determine the organic compounds present in a McDonald’s meal. OBJECTIVES: name the four biological macromolecules and their building blocks test food samples for the presence of lipids, proteins, and simple and complex sugars MATERIALS: McDonald’s food 12 Epitubes Benedicts’ solution (sugar) Lugol’s iodine solution (starch) forceps blender hot plate Biuret solution (protein) Sudan III or IV (lipids) foam holder pipettes beakers colored pencils ***Goggles are to be worn during this lab at all times**** Methods: Part 1: Testing Known Solutions (Control Tests) 1. Mark four epitubes with a “+”, mark four epitubes with a “-“ and four with “E.” 2. LIPIDS TEST: Place 10 drops of the “+oil” solution into your tube marked +L for the positive control. Place 10 drops of water into a tube (marked –L) for your negative control. Add 2 drops of Sudan solution into each test tube, and observe the color then record in the chart. DO NOT SHAKE. Continue with PART 2, LIPIDS. 3. PROTEIN TEST: Place 10 drops of the “+protein” solution into your tube marked +P for positive. Place 10 drops of water into a tube (-P) for your negative control. Add 8 drops of the Biuret solution to each test, shake well, and observe the color and record in the chart. Continue with PART 2, PROTEINS. 4. GLUCOSE TEST: Place 10 drops of the “+ Monosaccharide” solution into your PYREX tube marked +G for positive control. Place 10 drops of water into a tube (-G)for your negative control. Add 4 drops of Benedict’s solution in the tubes. Prepare the McMush tube as described below. Place all 3 tubes into the foam holder then place gently into a beaker of water that is boiling. Ask Ms. Bolton for help if the holder is already in the boiling water. Boil for 2-3 minutes (or until you see a color change) and remove with the forceps, observe the color, and record in the chart. 5. STARCH TEST: Place 10 drops of the “+starch” solution into your tube marked +S for positive control. Place 10 drops of water into a tube (-S) for your negative control. Add 3 drops of Lugol’s iodine solution into each test tube, shake, and observe the color; record in the chart. Continue with PART 2, STARCH. Part 2: Testing the McMush Meal: (Experimental Test) 1. LIPIDS (fats) TEST: Place 10 drops of the “McMush” solution one tube marked EL. Add 2 drops of Sudan solution into the tube, and observe the color then record in the chart. 2. PROTEIN TEST: Place 10 drops of the “McMush” solution one tube marked EP. Add 8 drops of the Biuret solution to the tube, shake as instructed, and observe the color and record in the chart. 3. GLUCOSE TEST: Place 10 drops of the “McMush” solution one PYREX tube marked EG. Add 4 drops of Benedict’s solution into the epitube. Place the test tube into the foam holder in the boiling water using the tweezers. Boil for 2-3 minutes (or until you notice any color change) and remove with the forceps, observe the color and record in the chart. 4. STARCH TEST: Place 10 drops of the “McMush” solution one tube marked ES. Add 3 drops of Lugol’s iodine solution into the test tube, shake as instructed, and observe the color then record in the chart. When finished, all epitubes should be washed thoroughly and turned upside down in your rack. Have Mrs. Cardellini check your station so that you can be dismissed. DATA CHART: (be sure to give this chart an appropriate title) Food Substances Fats Protein Glucose Starch You determine how to arrange the rest of your data with both the control and experimental tests. There won’t be quantitative data this time. DISCUSSION: 1. What was the purpose of the water in the first test? Why are controls important? 2. What is meant by the term ‘positive result’? 3. If you had an unknown solution that gave the following results, what can you conclude about the compounds present? Iodine – blue/black Benedicts – blue Sudan IV –red ring Biurets – light blue 4. State Standards 1H states you must know macromolecules (polysaccharides, proteins, nucleic acids, and lipids) in cells are synthesized from a small collection of simple precursors. List the precursors (monomers) for each of the four organic compounds. You may do this in chart form if you wish. CONCLUSION: Visit http://nutritiondata.self.com/ and enter your information on the DAILY NEEDS calculator (on bottom right). 1. How many calories do you burn in a day (look at est. energy requirement? 2. Scroll down to the very bottom where it shows you your recommended macronutrients. List these requirements. Think about what you ate yesterday – does it appear that you are eating your requirements? Explain. 3. Now visit your favorite fast food website (websites are also on my biology class weblinks) and create a full meal (entrée or sandwich, side and drink). Write out the meal you composed and its calorie and fat content. 4. How does the calorie and nutritional content relate to the amount of calories you burn in a day? What might happen if you continue these same eating habits as you grow older? + Protein + Monosacc. + Polysacc. + Lipid