Lab 2a: Dissecting a cell and examining its components
Purpose:
What are positive indicator tests for proteins, carbohydrates, and fats?
Do parts of an egg test positive for proteins, carbohydrates, and fats?
Do parts of an egg test positive for proteins, carbohydrates, and fats?
Materials:
Eggs
Beaker, 250 mL White vinegar Plastic wrap Slotted spoon Sodium chloride Distilled water Beaker, 100 mL Pipets, 5 mL |
Pipet pump, green
Tubes, glass, 13x100 mm Peg racks for 13x100 mm 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 1:
- Put a raw egg in a beaker of white vinegar. Label and cover it. Leave it for 24 to 48 hours. While the shell dissolves, do Part 2.
- After 24 to 48 hours. Gently pick up the egg with a slotted spoon and rinse it in water to remove the vinegar.
- To prove that water can go into and out of the cell freely, put the egg in 5% NaCl solution for 24 hours.
- Gently rinse off the egg again. Put the egg in a beaker of distilled water for 24 hours.
- To get the egg cell, slice open the egg's membranes, and let the egg white drip through the slots of the spoon into a 100 mL beaker. Don't pierce the yolk.
- Put the yolk in a separate container.
Procedure: Part 2:
Monosaccharide Indicator Standard Test
- Test for glucose: For 2 minutes, heat in a boiling hot water bath a mixture of 2mL of a 2% glucose solution and 2mL of Benedict's Solution. Record all changes and how long they take / last for.
- Test for water: For 2 minutes, heat in a boiling hot water bath a mixture of 2mL of deionized water and 2mL of Benedict's Solution. Record colors.
Starch Indicator Standard Test
- Test for starch: Mix 2mL of starch suspension with 0.25mL of Lugol's iodine. Mix and record colors.
- Test for water: Mix 2mL of deionized water with 0.25mL of Lugol's iodine. Mix and record colors.
Protein Indicator Standard Test
- Test for protein: Mix 2mL of gelatin with 1mL of Biuret reagent. Mix and record colors after 30 seconds.
- Test for water: Mix 2mL of deionized water with 1mL of Biuret reagent. Mix and record colors after 30 seconds.
Lipid Indicator Standard Test
- Test for lipid(s): Mix 2mL of oil with 60µL of Sudan IV. Record color.
- Test for water: Mix 2mL of deionized water with 60µL of Sudan IV. Record color.
Procedure: Part 3:
Test each part of the egg for monosaccharides, starch, protein, and lipids.
- Do all 4 tests above, but replace the substances tested with each part of the egg.
- Record the results of testing the egg membranes, the yolk, and the egg white for all four things.
- Give a number value to each test result and record color changes.
Data/Results:
Part 1:
CaCO3 + CH3COOH -> H2CO3 + H2O + CO2
Day 1: egg is put in vinegar
Day 2: shell is dissolved; egg is put in salt water
Day 3: egg is smaller; egg is put in deionized water
Day 4: egg is bigger; our egg white and yolk broke through the egg membrane
CaCO3 + CH3COOH -> H2CO3 + H2O + CO2
Day 1: egg is put in vinegar
Day 2: shell is dissolved; egg is put in salt water
Day 3: egg is smaller; egg is put in deionized water
Day 4: egg is bigger; our egg white and yolk broke through the egg membrane
Part 2:
Part 3:
Data Analysis/Conclusion:
The positive indicator tests for glucose, starch, protein, and lipids are Benedict's Solution, Lugol's iodine, Biuret reagent, and Sudan IV, respectively. From this experiment, we can see that the different egg parts have different compositions. The egg membrane has protein and lipids. The yolk has glucose and protein. The egg white has protein and lipids. You can click the Data Table buttons above to see our results for negative and positive tests.
Reflection:
- What did you like/find interesting? I found it very interesting that you can think of an egg as a model of a cell because it works in similar ways.
- How did you and your partner collaborate? My partner and I worked very well together and we were quick and efficient in completing the lab.
- What would you do differently next time? Some things that I think could be improved upon for next time would be time management and clean-up. Many of the materials were not put away properly.