Biological Macromolecules
Exercise 1: Starch and Sugar
Data Table 1. Benedict's Reagent Data.
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Sample
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Initial Color
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Final Color
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Reducing Sugar Present in Sample? Y or N
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dH2O
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Albumin
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Unknown
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Milk
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Glucose
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Data Table 2. Lugol's Iodine Data.
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Sample
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Initial Color
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Final Color
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Starch Present in Sample? Y or N
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dH2O
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Albumin
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Unknown
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Milk
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Starch
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Raw Potato
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Questions
A. In each of the two tests (starch and sugar) a positive and negative control was used. What was the positive control in each of the tests and what was the negative control. Explain your answers.
B. Did the Benedict's test for reducing sugars net a positive or negative result for milk? Research the sugar content of milk and the definition of a reducing sugar to explain if your result is what you would expect.
C. Based on your results, is sugar and/or starch present in your Unknown? Use your results to explain your answer.
Exercise 2: Proteins and Lipids
Data Table 3. Biuret's Reagent Data.
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Sample
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Initial Color
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Intermediate Color
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Final Color
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Protein Present in Sample? Y or N
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dH2O
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Albumin
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Unknown
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Milk
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Data Table 4. Lipid Observations.
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Sample
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Sample Observations
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Lipid Present in Sample? Y or N
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Distilled water
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Albumin
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Unknown
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Milk
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Vegetable oil
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Questions
A. Review the Data Tables in Exercises 1 and 2. Compare the results of the Unknown for all tests to the results for the various known samples to determine the identity of the Unknown. Explain the identity of the Unknown using your experiment results in the exercises to help explain and support your answer.
B. Eggs are known to contain cholesterol which is a lipid. Did your experiment results indicate a presence of lipids in the albumin solution? Think about this result and where cholesterol is present in eggs to explain how your results support or reject cholesterol in eggs. How could you test this? Explain the experiment that you would perform to test this.