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Work out the results expected of standard tests used by scientists to identify the presence of specific chemicals which may be found in cells.

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CHEMICAL TESTS FOR CELLULAR MOLECULES. Experiment Number 1 03-02-04 Partners: Philippa Pretorius and Claire Walter Suzanne Poulgrain AIM: To work out the results expected of standard tests used by scientists to identify the presence of specific chemicals which may be found in cells. A. TEST FOR PROTEIN PROCEDURE: 1. 3mL of egg white solution was placed in a test tube. 2. 1mL each of dilute sodium hydroxide solution and dilute copper sulfate solution was added. 3. The resulting liquid was observed and described in Table 1. 4. Steps 1, 2 and 3 were repeated using water in place of egg white solution. 5. Steps 1, 2 and 3 were repeated using bread, meat and biscuit. All ingredients were tested separately. RESULTS: Table 1 - Results of Protein Testing Colour Original Colour Blue Egg white solution Violet Water Blue Bread Blue Meat Violet Biscuit Blue DISCUSSION / CONCLUSIONS: Protein is an important cell chemical and is constantly needed by the body. As a result of this it is found in many common food stuffs. In this test, water was used as a control and shows the results when no protein is present. When water, bread and biscuit were tested there was no change in the colour of the solution. ...read more.


The results of this investigation show that glucose, sweet biscuit and banana react similarly, if not as strong, to this test. Since it is known that the results for glucose will be similar for other materials containing glucose it can be concluded that sweet biscuit and banana contain glucose, although not at the same concentration. In conclusion this test has identified glucose within some common materials. D. Clinistix Test for Glucose PROCEDURE: 1. The original colour of the clinistix was noted and recorded in Table 4. 2. 3mL of glucose solution was placed in a test tube. A clinistix was added and the colour change noted in table 4. 3. The above 2 steps were repeated with water in place of the glucose solution 4. The above 2 steps were repeated using ground: bread, sweet biscuit and lolly. All materials were tested separately. RESULTS: Table 4 - Results of Glucose Testing using Clinistix Colour Concentration Original Colour Pink Negative - (0) Glucose Dark Purple +++ Dark - (28mmol/L) Water Pink Negative - (0) Bread Medium Purple ++ Medium - (14-28mmol/L) Sweet Biscuit Medium Purple ++ Medium - (14-28mmol/L) Lolly Dark Purple +++ Dark - (28mmol/L) DISCUSSION / CONCLUSIONS: Water is used as a control in this investigation and shows the results when no glucose is present. ...read more.


RESULTS: Table 6 - Results of Lipid Testing Initial Clarity Final Clarity Original Clarity Opaque Opaque Oil translucent Transparent Water Opaque Opaque Banana Translucent Translucent Potato Opaque Opaque Butter translucent Transparent DISCUSSION / CONCLUSION: Lipids are an essential part of all diets as they help with four tasks: * They serve as structural components of biological membranes. * They provide energy reserves. * Both lipids and lipid derivatives serve as vitamins and hormones. * Lipophilic bile acids aid in lipid solubilization. As water contain no lipids it was used as a control. The results with oil are the desired results, for they are liquid lipids. Both banana and butter were initially translucent, however after ten minutes butter became transparent. This suggests that there is a moderate amount of lipid in banana and a high level of lipid in butter. The results for potato are much like those for water, and suggest that they contain limited lipids. In conclusion this test has identified lipids within some common materials. SUMMARY TABLE: Chemical Chemical or Agent Used Desired Colour change or Effect Protein Sodium Hydroxide + Copper Sulfate When protein present, turns Violet Starch Lugol's iodine Solution When starch present, turns Blue Glucose Benedict's Solution When glucose present, turns Orange Glucose Clinistix When glucose present, turns purple Cellulose Conc. Sulfuric Acid + Lugol's Iodine Solution When broken down cellulose present, turns Brown - Red Lipids Brown Paper When lipids present, paper turns Transparent ...read more.

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