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Bell Work • List the 4 major macromolecules and the monomers for each Carbohydrates = monosaccharides Proteins = amino acids Lipids = fatty acids Nucleic Acids = nucleotides IDENTIFYING MACROMOLECULES IN Nutrients LAB Mrs. Stewart Honors Biology Lab Objective Identify the presence of major nutrients such as simple carbohydrates (glucose), complex carbohydrates (starch), protein and fat in common foods. In this lab, with the use of indicators as chemical detection tools, you will analyze a variety of foods for the presence of macromolecule nutrients. Detection is based upon observing a chemical change that takes place most often a change in color. What is an indicator? • Indicators are chemical compounds used to detect the presence of other compounds. Test for Simple Carbohydrates Benedict’s solution • Benedict's solution is a chemical indicator for simple sugars such as glucose: C6H12O6. Negative: Aqua blue Positive: Red/ orange/ yellow/ green Benedict’s Test • The intensity of the color change is related to the concentration of simple sugars present • The color change is a rainbow spectrum: – Red (very positive) – Orange – Yellow – Green – Blue (Negative) Test for Simple Carbohydrates Benedict’s solution • Unlike some other indicators, Benedict’s solution does not work at room temperature it must be heated first. Question Why didn’t the test tube containing starch change colors? Test for Complex Carbohydrates Iodine Solution • Detects complex carbohydrates (polysaccharides) • Iodine solution color change = blue to black Test for Complex Carbohydrates Iodine solution • Iodine solution is an indicator for a molecule called starch. • Starch is a huge molecule made up of hundreds of simple sugar molecules (such as glucose) connected to each other. Test for Protein (amino acids) Biuret solution • Biuret solution dark violet blue to pinkish purple Test for Fats (lipids) Sudan III • If lipids are present the Sudan III will stain them reddish-orange (positive test). INDICATOR Benedict’s solution MACROMOLECULE simple carbohydrate NEGATIVE TEST blue POSITIVE TEST Green, yellow, orange, brick red Iodine solution complex carbohydrate dark red black Biuret solution protein blue violet, black Sudan IV lipid dark red reddishorange It’s up to you to save us! • New type of zombie emerges • They thrive by feeding on simple sugars • Complex carbs & proteins are deadly to them • What will be the best food to combat this threat? – Milk, yogurt or oatmeal? Test Results • Milk (regular cow’s milk – whole) Test Color Benedict’s Solution Orange Lugol’s Iodine Reddish/brown Biuret’s Solution Purple Sudan III Red throughout Test Results • Yogurt (regular, fat-free) Test Color Benedict’s Solution Red Lugol’s Iodine Reddish-brown at bottom Biuret’s Solution Purple Sudan III Red layer at top only Test Results • Oatmeal Test Color Benedict’s Solution Blue Lugol’s Iodine Dark blue/black Biuret’s Solution Purple Sudan III Red layer on top only
