"Dissecting" a "Cell" and Examining Its Contents
Purpose: What are positive indicator tests for proteins, carbohydrates, and fats? Do parts of an egg test positive for protein, carbohydrates, and/or fats?
Materials:
Eggs
250 ml Beaker
100 ml Beaker
White Vinegar
Plastic Wrap
Slotted Spoon
Sodium Chloride
Distilled Water
5 ml Pipets
Green Pipet Pump
13x100 mm Glass Tubes
13x100 mm Peg Racks for Tubes
Glucose(dextrose)
Benedict's Solution
Hot Plate Stirrer
Test Tube Holder
Soluble Starch
Lugol's Iodine Solution
Vortex Mixer
Gelatin
Sodium Hydroxide
Cupric Sulfate 5-Hydrate
Oil
Suden IV Solution
Scalpel Handles #4
Scalpel Blades #22 for #4 Handles
Plastic Trays
Procedure Part I: Seperating Cell Structures
Materials:
Eggs
250 ml Beaker
100 ml Beaker
White Vinegar
Plastic Wrap
Slotted Spoon
Sodium Chloride
Distilled Water
5 ml Pipets
Green Pipet Pump
13x100 mm Glass Tubes
13x100 mm Peg Racks for Tubes
Glucose(dextrose)
Benedict's Solution
Hot Plate Stirrer
Test Tube Holder
Soluble Starch
Lugol's Iodine Solution
Vortex Mixer
Gelatin
Sodium Hydroxide
Cupric Sulfate 5-Hydrate
Oil
Suden IV Solution
Scalpel Handles #4
Scalpel Blades #22 for #4 Handles
Plastic Trays
Procedure Part I: Seperating Cell Structures
- Place uncooked egg in beaker of vinegar. Label and cover w/ plastic wrap, leave for 24-48 hours.
- Pick up dissolved egg w/ slotted spoon and rinse in water.
- Outer cell membrane provides a good cell membrane model. They are thin, flexible, and permeable to some substances. To verify that water can enter and leave membrane place the egg in a beaker of 5% NaC1 solution for 24 hours. Describe the appearance after 24 hours.
- Gently rinse egg in water again, and then place the egg in a beaker of distilled water for another 24 hours. Describe the appearance, what could have changed it?
- Gently slice open the egg's membrane, 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.
- Place yolk into another beaker, and set aside egg membranes.
Part II: Testing Standard Solutions
Record results in a data table:
Record results in a data table:
Standard
(Molecule Tested) glucose starch protein fat |
Indicator Used
Benedict's solution Lugol's iodine Biuret reagent none--paper bag test or Sudan IV |
Description Positive Control Test Results
|
Description Negative Control Test Results
|
Monosaccharide Indicator Standard Test:
- Test for glucose: Mix 2mL of 2% glucose + 2mL of Benedict's, heat for 2 mins in boiling water, record all color changes and the length of time for each color to appear.
- Test for water: mix 2mL of deionized water with 2mL of Benedict's. Heat for 2 mins in boiling water, record all color changes and time for color to appear.
Starch Indicator Standard Test:
- Test for starch: mix 2mL of well-mixed starch suspension + 0.25 mL of Lugol's iodine. DO NOT HEAT; record color change
- Test for water: mix 2mL of deionized water with 0.25 mL of Lugol's iodine. DO NOT HEAT; record color change.
Protein Indicator Standard Test:
- Test for protein: 2mL of gelatin in test tube. Add 0.5mL of 10% NaOH and gently mix. Add 0.25mL of 5% copper sulfate and mix. Record color change after 30 seconds.
- Test for water: 2mL of deionized water + 0.5mL of 10% NaOH and gently vortex. Add 0.25mL of 5% CuSO4 and mix. Record color change after 30 seconds.
Lipid Indicator Standard Test:
- Test for lipids: Place a drop of oil on paper bag. Sit for 10 mins. Hold paper to light and record how much light passes through the oil.
- Test for water: Place a drop of water on paper bag. Sit for 10 mins. Hold paper to light and record light.
Part III: Molecular Composition of Egg Components
- Conduct each indicator test in Part II, but substitute each egg component to be tested. MAKE SURE YOU DO NOT ADD ANY OF THE STANDARD SOLUTIONS!
- Record the results in another data table
- Include a number with each test result and a brief description of the color changes
Results:
Part I: Qualitative observations
After the egg was in the vinegar solution it produced H2O, CO2, and H2CO3 water went into the egg membrane
1. Calcium Carbonate + Vinegar -> Water + Carbon Dioxide: The egg was placed into vinegar and it dissolved the shell, leaving behind carbon dioxide and water
2. Egg +salt water; Salt water went into egg and water came outside of the egg, making the egg appear to be smaller.
3. Egg + deionized water; When the egg was placed back into water, the salt water left, and the water returned into the egg, making it look bigger this time
Part I: Qualitative observations
After the egg was in the vinegar solution it produced H2O, CO2, and H2CO3 water went into the egg membrane
1. Calcium Carbonate + Vinegar -> Water + Carbon Dioxide: The egg was placed into vinegar and it dissolved the shell, leaving behind carbon dioxide and water
2. Egg +salt water; Salt water went into egg and water came outside of the egg, making the egg appear to be smaller.
3. Egg + deionized water; When the egg was placed back into water, the salt water left, and the water returned into the egg, making it look bigger this time
Part II & Part III Data Tables:
lab_2a_data.gdoc | |
File Size: | 0 kb |
File Type: | gdoc |
Analyzing and Concluding:
For this lab we started by doing tests for things like proteins with items we know have protein and ones that do not, so that we know a negative and positive test. Then we substituted the substances with egg components, and recorded the color changes that occurred. Our results found that some components did test positive for some things. The components were especially positive in protein.
There were probably some experimental errors, such as human error and things that may have went wrong with the solutions. The amount of each solution might not have been the same every time, nor the concentration of solutions. In the future we should be more careful with our measurements. There also may have been error with the temperature of the boiling water when we used that to heat up solutions. The water temperature would not have been the exact same every time, and we should have used a device like a thermometer to make sure the temperatures were the same.
This experiment also models real life indicator tests. Scientists also use this kind of method to test for things in substances. In addition to that, there are drug indicator tests that test positive or negative if you have used the drug or not, and also tests that indicate the pH of things or their concentration level, like your blood sugar level for diabetes.
For this lab we started by doing tests for things like proteins with items we know have protein and ones that do not, so that we know a negative and positive test. Then we substituted the substances with egg components, and recorded the color changes that occurred. Our results found that some components did test positive for some things. The components were especially positive in protein.
There were probably some experimental errors, such as human error and things that may have went wrong with the solutions. The amount of each solution might not have been the same every time, nor the concentration of solutions. In the future we should be more careful with our measurements. There also may have been error with the temperature of the boiling water when we used that to heat up solutions. The water temperature would not have been the exact same every time, and we should have used a device like a thermometer to make sure the temperatures were the same.
This experiment also models real life indicator tests. Scientists also use this kind of method to test for things in substances. In addition to that, there are drug indicator tests that test positive or negative if you have used the drug or not, and also tests that indicate the pH of things or their concentration level, like your blood sugar level for diabetes.
Reflection:
I enjoyed this lab a lot. It was fun coming in and seeing how the egg was changing day by day, especially when the shell was dissolving. I found it interesting that the egg had built up a lot of pressure while it sat there, because when we were supposed to slice it gently to let the egg white drip out my whole egg exploded, and this was very unexpected. I also enjoyed when the solutions would change colors that I didn't expect, like when the Benedict's solution turned 4 colors when testing positive.
My partner in the lab was Max Von Blankenburg. We both collaborated well, coordinating making the solutions and sharing the jobs equally. My only complaint was that I had to do a little more when he was finishing the surface tension water lab, but it didn't bother me much.
I enjoyed this lab a lot. It was fun coming in and seeing how the egg was changing day by day, especially when the shell was dissolving. I found it interesting that the egg had built up a lot of pressure while it sat there, because when we were supposed to slice it gently to let the egg white drip out my whole egg exploded, and this was very unexpected. I also enjoyed when the solutions would change colors that I didn't expect, like when the Benedict's solution turned 4 colors when testing positive.
My partner in the lab was Max Von Blankenburg. We both collaborated well, coordinating making the solutions and sharing the jobs equally. My only complaint was that I had to do a little more when he was finishing the surface tension water lab, but it didn't bother me much.