Purpose:
The purpose of this lab is to determine the positive indicator of proteins, carbohydrates, and fats and use that information to find which parts of an egg test positive for protein, carbohydrates, and fats.
MAterials:
Eggs
Beaker (250 mL) White Vinegar Plastic Wrap Slotted Spoon Sodium Chloride Distilled Water Beaker (100 mL) Pipets (5 mL) Pipets Pump (Green) |
Tubes (Glass, 13x100mm)
Peg Racks (For Tubes) Glucose (Dextrose) Benedict's Solution Hot Plate Stirrer Test Tube Holder Starch (Soluble) Lugol's Iodine Solution Vortex Mixer Gelatin |
Sodium Hydroxide
Cupric Sulfate 5-Hydrate Oil Sudan IV Solution Scalpel Handles (#4) Scalpel Blades (#22, for #4 Handles) Trays (Plastic) |
Procedure:
Part I:
- Place an uncooked egg into a beaker of white vinegar. Label and cover it with plastic wrap. Leave it for 24 to 48 hours. While the shell dissolves, proceed to Part II.
- After 24-48 hours, the shell should have dissolved in the vinegar (acetic acid). Gently pick up the egg with a slotted spoon and rinse it in water to remove vinegar. A chemical reaction has happened here. What chemicals were involved as reactants and products?
- Feel the outer membranes of the cell. The outer membrane which is different from the membrane around the yolk, provides a good model of a cell membrane. They are thin and flexible. They are permeable to some substances. To verify that water can enter and leave the cell easily, place the egg in a beaker of 5% NaCl solution for 24 hours. Describe the appearance of the egg after 24 hours. What may have caused the change in appearance?
- Gently rinse off the egg again with water. Then place the egg in a beaker of distilled water for 24 hours. Describe the appearance of the egg after 24 hours. What caused the change in appearance?
- To retrieve the egg cell, gently slice open the egg's membranes and let the egg white drip through the slots of the spoon into a 100 mL beaker. Try to get all of the egg white into the beaker without piercing the yolk (egg cell with a clear, flimsy cell membrane around it).
- Place the egg yolk into another beaker, and set aside the egg membranes.
Part II
Monosaccharide Indicator Standard Test
- Test for glucose: in a test tube, mix 2 mL of 2% glucose (a monosaccharide) solution with 2 mL of Benedict's Solution. Heat for 2 minutes in a boiling hot water bath (100 mL of water in a 200 mL beaker at 100 degrees Celsius). Record all color changes and the length of time for each color to appear.
- Test for water (negative control): In a test tube, mix 2 mL of deionized water with 2 mL of Benedict's Solution. Heat for 2 minutes in a boiling hot water bath (100 mL of water in a 200 mL beaker at 100 degrees Celsius). Record all color changes and the amount of time for each color to appear.
Starch Indicator Standard Test
- Test for starch: In a test tube, mix 2 mL of well-mixed starch suspension with 0.25 mL of Lugol's iodine. Gently swirl to mix. DO NOT HEAT. Record the color change.
- Test for water (negative control): In a test tube, mix 2 mL of deionized water with 0.25 mL of Lugol's iodine. Gently swirl to mix. DO NOT HEAT. Record the color change.
Protein Indicator Standard Test (Wear goggles and gloves!)
- Test for protein: Place 2 mL of gelatin solution in test tube. Add 0.5 mL of 10% NaOH and gently vortex to mix. Add 0.25 mL of 5% copper sulfate (CuSO4) and gently mix to form Biuret reagent. Mix well and record color change after 30 seconds.
- Test for water (negative control): Place 2 mL of deionized water in test tube. Add 0.5 mL od 10% NaOH, and gently vortex to mix. Add 0.25 mL of 5% CuSO4 and gently mix ell. Record color change after 30 seconds.
Lipid Indicator Standard Test
- Test for lipid(s): Mix 2 mL of oil and 60 uL of Sudan IV in test tube. Record color change.
- Test for water: Mix 2 mL of oil and 60 uL of Sudan IV in test tube. Record color change.
Part III
- Conduct each test in Part II, but test egg component for sugar, starch, protein, and fat.
- Record the results of the egg membrane, yolk, and egg white when tested.
- Use a number to indicate the strength or weakness in the color variation.
Data/Results:
Part I
Chemical Reaction:
CaCO3 + CH3COOH --> H2CO3 + H2O + CO2
Day 1:
On Day 1, we put a raw egg into a beaker and added vinegar in order to dissolve the egg's shell.
Day 2:
On Day 2, the shell was dissolved and we added 5% NaCl solution to the beaker. The NaCl went inside of the egg while the water went outside the egg. This shift made the egg become smaller giving the egg a "shrunken" appearance.
Day 3:
On Day 3, we added distilled water. which went inside of the egg making it larger. The pressure of the water was seen when cutting the egg to separate different parts: it exploded all over the table.
CaCO3 + CH3COOH --> H2CO3 + H2O + CO2
Day 1:
On Day 1, we put a raw egg into a beaker and added vinegar in order to dissolve the egg's shell.
Day 2:
On Day 2, the shell was dissolved and we added 5% NaCl solution to the beaker. The NaCl went inside of the egg while the water went outside the egg. This shift made the egg become smaller giving the egg a "shrunken" appearance.
Day 3:
On Day 3, we added distilled water. which went inside of the egg making it larger. The pressure of the water was seen when cutting the egg to separate different parts: it exploded all over the table.
Part II
Part III
Data Analysis:
In this lab, we found the positive indicators for various tests for materials and then used those results to test egg components for glucose, starch, protein, and lipids. The positive glucose test turned orange and the negative control test remained blue. The positive starch test remained black, while the negative control turned a light shade of red-orange. The positive protein test turned purple and the negative control was clear with a blue hint. The positive lipid test turned the liquid a milky pink, while the negative control test became a clear pink.
After finding both our positive and negative indicators, we tested the egg components with the same experiments. The yolk did not test positive in any of our tests. The membrane contained starch, protein, and lipids. Similarly, the white also had protein, starch, and lipids.
Errors that could have led to false results include (but are in no way limited to) cross-contamination, chaos/lack of organized experimentation, and proper measuring.
Some variations to our experiment that we could add are using different solutions as indicators, testing other items, or even trying different species' eggs.
The indicator-style test used in this experiment could be taken and used in other ways like testing alcohol-blood levels, how well teeth have been brushed, or the pH level of a given substance.
After finding both our positive and negative indicators, we tested the egg components with the same experiments. The yolk did not test positive in any of our tests. The membrane contained starch, protein, and lipids. Similarly, the white also had protein, starch, and lipids.
Errors that could have led to false results include (but are in no way limited to) cross-contamination, chaos/lack of organized experimentation, and proper measuring.
Some variations to our experiment that we could add are using different solutions as indicators, testing other items, or even trying different species' eggs.
The indicator-style test used in this experiment could be taken and used in other ways like testing alcohol-blood levels, how well teeth have been brushed, or the pH level of a given substance.
Reflection:
During this lab, I really enjoyed the overall experience, however my favorite parts were learning how to use everything, using the vortex, and testing the various egg parts in each test.
My partner and I were able to collaborate really well. We multi-tasked effectively and weren't at all pressed for time. We both had a good understanding of the content and distributed work evenly and fairly. We worked hard and had lots of time to spare at the end while still having accurate results. even through all the mess, we had good attitudes and pushed through.
If we were to repeat this, I would make table groups smaller and separate supplies better. Multiple times we would set up an experiment and our materials would be used by another group. We also had cross-contamination due to mislabeling of tubes. I would also try to make the biotech room less crowded and chaotic by swapping groups in while having another activity to do in another area. Overall, the experiments weren't awful, but could have gone a lot better.
My partner and I were able to collaborate really well. We multi-tasked effectively and weren't at all pressed for time. We both had a good understanding of the content and distributed work evenly and fairly. We worked hard and had lots of time to spare at the end while still having accurate results. even through all the mess, we had good attitudes and pushed through.
If we were to repeat this, I would make table groups smaller and separate supplies better. Multiple times we would set up an experiment and our materials would be used by another group. We also had cross-contamination due to mislabeling of tubes. I would also try to make the biotech room less crowded and chaotic by swapping groups in while having another activity to do in another area. Overall, the experiments weren't awful, but could have gone a lot better.