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What Is The Purpose Of Lab 1.1 Testing For Protein Molecules

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Experiment 1: Testing for Proteins The protein molecules in many foods provide the amino acid building blocks required by our own cells to produce new proteins. To determine whether a sample contains protein, a reagent called Biuret solution is used. Biuret solution contains copper ions. However, the chemical state of the copper ions in Biuret solution causes them to form a chemical complex with the peptide bonds between amino acids (when present), changing the color of the solution. Biuret solution is normally blue, but changes to pink when short peptides are present and to violet when long polypeptides are present. Figure 6: Biuret solution only is located on the far left side of the image (blue). Note the transition from blue to …show more content…

Swirl each tube to mix. 8. Record the final color in Table 1. Note: Protein is present in the sample if a light purple color is observed. Table 1: Testing for Proteins Results Sample Initial Color Final Color Protein Present 1 - Albumin Solution 2 - Gelatin Solution 3 - Glucose 4 - Water 5 - Unknown Post-Lab Questions 1. Record your hypothesis about what will happen when Biuret solution is mixed with the solutions from test tubes 1, 2, 3, and 4 here. Be sure to use scientific reasoning to support your hypothesis. 2. Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with the Biuret solution and each sample solution. 3. Diet and nutrition are closely linked to the study of biomolecules. How should you monitor your food intake to insure the cells in your body have the materials necessary to function? 4. There are other types of reagents used to determine what type of biomolecule a substance is. For example, copper ions present in Benedict’s reagent reacts with the free end of any reducing sugars, such as glucose, when heated. Originally blue in color, these copper ions are reduced by the sugar, and produce an orange-red colored precipitate. Alternatively, iodine-potassium iodide (IKI) may also be used when working with starch. IKI contains special tri-iodine ions which interact with the coiled structure of a starch

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