Lab 2 Proteins and Starches

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School

Florida State College at Jacksonville *

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Course

2010C

Subject

Chemistry

Date

Feb 20, 2024

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docx

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Uploaded by EarlFlagFish47

Rea Bace BSC2010C Lab 2: Proteins and Starches Protein and Starch Detection in Various Solutions Test 1: Proteins hypothesis If I test DI water, milk, 50% egg white solution, and 1% sucrose, then the milk and egg white solution will show the presence of protein, while DI water and the 1% sucrose will not. Given that distilled water typically lacks macromolecules, I would guess that it will not contain protein. Since milk and eggs are known to be a source of protein, it is expected that both will test positive. The 1% sucrose is a simple sugar therefore I expect that it would lack protein. purpose The purpose of this experiment is to investigate the presence of proteins in various solutions. The solutions used in this experiment are distilled water, milk, 50% egg white solution, and 1% sucrose solution. The protein indicator utilized in this experiment is Biuret reagent. This test will help in understanding the effectiveness of the reactant in detecting protein macromolecules in diverse liquid substances.

methods materials: test tube rack four to five test tubes transfer pipette protective glasses three pieces of paper bag deionized water (DI water) evaporated milk 50% egg white solution 1% sucrose solution biuret reagent method: 1. Label test tubes with a wax pencil. 2. Add three milliliters of each substance to each test tube. (one substance in one tube) 3. Add five drops of the reagent to each of the test tubes. 4. Swirl to mix. 5. Record the results. results In this experiment, the biuret reagent was used to test the presence of proteins in four different solutions. The solutions that tested negative for proteins were distilled water and the 1% sucrose solution. Both showed no color change indicating negative results. The solutions that tested positive for proteins were 50% egg white solution and evaporated milk. Both solutions showed a color change to purple confirming a positive result for proteins.

conclusion This experiment supported the initial hypothesis: “If I test DI water, milk, 50% egg white solution, and 1% sucrose, then the milk and egg white solution will show the presence of protein, while DI water and the 1% sucrose will not.” As the tested substances were highly predictable, the test results were exactly as expected. This test confirmed the Biuret solution's ability to detect the presence of protein in solutions. --------------------------------------------------------------------------------------------------------------------- Test 2: Starches hypothesis statement If I test the test tubes containing DI water, 1% starch solution, onion juice, and 1% sucrose solution, then the 1% starch solution will show presence of starch, while DI water, onion juice, 1% sucrose solution will test negative for starch. Given that distilled water typically lacks macromolecules, my guess would be that it will not contain starch. Along with distilled water, onion juice and 1% sucrose solution typically do not contain starch therefore they will also test negative for starch. 1% starch solution obviously has starch in it so it will test positive for starch. purpose statement The purpose of this experiment is to investigate the presence of starches and various solutions. The solutions tested in this experiment are DI water, 1% sucrose solution, 1% starch solution, and onion juice. The starch indicator utilized in this experiment is iodine also known as

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Benedict's reagent. This test will help us understand the effectiveness of the reactant in detecting starch macromolecules and diverse liquid substances. methods materials: test tube rack four to five test tubes transfer pipette protective glasses three pieces of paper bag deionized water (DI water) 1% sucrose solution 1% starch solution onion juice Benedict's reagent (iodine) methods: 1. Label test tubes with a wax pencil. 2. Add three milliliters of each substance to each test tube. (one substance in one tube) 3. Add five drops of the reagent to each of the test tubes. 4. Swirl test tubes to mix. 5. Record the results. results In this experiment, the benedicts reagent was used to test the presence of starches in four different solutions. The solutions that tested negative for starches were distilled water, 1% sucrose solution, and onion juice. All three of these substances showed a color change to yellow

confirming a negative result for starches. The solution that tested positive for starches was 1% starch solution. This solution showed a color change to purple confirming a positive result for starch. conclusion section This experiment supported the initial hypothesis: “If I test the test tubes containing DI water, 1% starch solution, onion juice, and 1% sucrose solution, then the 1% starch solution will show the presence of starch, while DI water, onion juice, 1% sucrose solution will test negative for starch.” As the tested substances were also highly predictable, the test results were exactly as expected. This test confirmed the Benedict reagent’s ability to detect the presence of starch in solutions.