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3 Chemical Composition of Cells (LM pages 29-42) Time Estimate for Entire Lab: 2.0 hours To reduce experimental time and preparation time, the following procedures can be set up as demonstra- tions: Enzyme Function of Proteins (LM page 32), Starch Composition (LM page 37), and Emulsification of Lipids (LM page 39). In any case, to allow enough time for digestion, you may wish to do Enzyme Function of Proteins first, and Starch Composition immediately thereafter. Special Requirements 1. Incubation. Incubation is required for Enzyme Function of Proteins and for Starch Composition. 2. Fresh material. The potato and onion for Carbohydrates (LM page 34) and the materials for Testing the Chemical Composition of Everyday Materials and an Unknown (LM page 41) can be obtained locally, close to time of use. Seventh Edition Changes This was Lab 2 in the previous edition. New or revised figures: 3.1 Peptide bond; 3.3 Glygose; 3.4 Maltose; 3.5 Starch; 3.6 Synthesis of a fat; 3.7 Emulsification J Notes 1. Test tubes. The exercises in this laboratory require students to add solutions to test tubes. As an expedient, the students are asked QAR off the tubes at various centimeter levels with a ruler and then to fill to these marks. You may p1 to have students use a standard method of measuring volume, such as with a graduated ler or a pipette. Most experiments use the standard size test tube. A few experiments require the large,size test tube. Mini test tubes can be substituted for most laboratory exercises as long as the total volume in a given tube does not exceed 9 cm. This will reduce the volume of reagents used by approximately one-third. Test tube sizes /volumes are as follows: Mini 13 x 100 mm (Carolina 73-0008) lem = 1.0 ml Standard 16 * 150 mm (Carolina 73-0014) lem=15ml Medium large 20 x 150 mm (Carolina 73-0019) lem=24 ml Large 25 x 150 mm (Carolina 73-0025) lem =4.0 ml 2. Students’ results. If students’ results are not as expected, you may wish to test the reagents. 3. Chemical solutions. All chemicals for this laboratory can be purchased from Carolina Biological Supply. Information in the “Materials and Preparations” section may be helpful to those who wish to prepare their own. 4. An incubator is recommended for some tests. However, a hot water bath (hot plate, beaker of water, Celsius thermometer, test-tube clamp, beaker clamps, boiling chips) will also work. MATERIALS AND PREPARATIONS" All Exercises wax pencils rulers, plastic millimeter test tubes and racks water, distilled boiling chips, pumice (Carolina 84-8278, -8280) 
