Lab 2a- Dissecting a Cell and Examining its Components
Monday, August 25, 2014
Purpose: The purpose of the lab is to use indicator tests to discover protein, carbohydrates, and fats in an egg(cell).
Materials: Eggs, Beaker(250 mL and 100 mL), White Vinegar, Plastic Wrap, Slotted Spoon, Sodium Chloride, Distilled Water, Pipets(5 mL), Glass Tubes(13x100mm), Peg Racks for tubes(13x100mm), Test Tube Holder, Glucose(dextrose), Benedict's Solution, Hot Plate Stirrer, Soluble Starch, Lugol's Iodine Solution, Vortex Mixer, Gelatin, Sodium Hydroxide, Cupric Sulfate 5-hydrate, Oil, Sudan IV Solution, Scalpel Handles(#4), Scalpel Blades(#22), Plastic Trays
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Procedure Part One: Place an uncooked egg into a beaker of white vinegar and cover it with plastic wrap. After labeling it, leave it for one to two days so the shell dissolves. After the egg's shell dissolves, rinse the vinegar off the egg with water. Observe the chemical reaction that has occurred, along with the reactants and products involved. Feel the outer membrane of the cell and observe the properties. Use a beaker of five percent Na-Cl solution to check if water can enter the cell through the permeable membrane. After twenty-four hours, record the appearance of the egg; wash the egg in water. Then test the egg in a beaker of distilled water for twenty-four hours before observing the changes of appearance. Slice open the membrane so the egg white drips through the slotted spoon into a 100 mL beaker. Don't pierce the yolk while draining the egg white. Separate the egg yolk into a different beaker.
Part One Observations: After the vinegar was rinsed off, I noticed the egg seemed much more fragile. When poked, the egg jiggled and the membrane felt like consolidated gel. The membrane was opaque and I could see the differences in the color of the yolk and egg whites; the membrane also kept the egg together. After twenty-four hours of the egg resting in salt water, the egg seemed smaller and shrunken. This is the effect of osmosis; the Na-Cl in the water moved to the less concentrated egg and the water inside the egg traveled outside the membrane. After placing the egg in distilled water, the egg appeared larger with a lot of pressure. This is because the Na-Cl moved to the water surrounding the egg and the distilled water entered the membrane of the egg, expanding its size. While piercing the membrane, the egg contents exploded due to the pressure.
Procedure Part Two:
1. Test for glucose by mixing 2 mL of 2 percent glucose solution with 2 mL of Benedict's solution and heat for 2 minutes in boiling water. Record color changes and time overlapped before each color change for test. (Monosaccharide Indicator Standard Test)
2. Test for starch by gently swirling 2 mL of starch suspension together with 0.25 mL of Lugol's iodine. Record the color changes. (Starch Indicator Standard Test)
1. Test for glucose by mixing 2 mL of 2 percent glucose solution with 2 mL of Benedict's solution and heat for 2 minutes in boiling water. Record color changes and time overlapped before each color change for test. (Monosaccharide Indicator Standard Test)
2. Test for starch by gently swirling 2 mL of starch suspension together with 0.25 mL of Lugol's iodine. Record the color changes. (Starch Indicator Standard Test)
3. To test protein, use vortex machine to mix 2 mL of gelatin and 0.5 mL of Biuret reagent. For notes, observe the test tubes after 30 seconds and record the color change. (Protein Indicator Standard Test)
4. Mix 2 mL of oil and 60 uL of Sudan IV in a test tube; this shows the lipids. (Lipid Indicator Standard Test) As a baseline control variable, substitute the standard substance with water and perform the exact same experiments. Record the observations and compare data. |
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Results of Standard Molecule Testing Using Different Indicators
Standard
(Molecule Tested) Glucose Starch Protein Fat |
Indicator Used
Benedict's Solution Lugol's Iodine Biuret Reagent Sudan IV |
Description Positive Control Test Results
-Top green(60 sec); bottom murky brown/orange(90 sec); middle stayed lighter blue(15 sec) -Dark brown and black; stayed very dark brown; not transparent(Instantaneous color change) -Light purple; more clear with hue of lavender; seems opaque/see-through(Instantaneous change) -Cloudy, non-transparent pink and white; looks like rose colored clouds(Instantaneous color change) |
Description Negative Control Test Results
-No color change; stayed dark shade of blue entire duration -Turns red/orange; stayed fiery color; lighter tinge, -Stayed clear; did not change color or appearance at all -Opaque very light pink; still transparent; color lined edges of water(meniscus) |
Procedure Part Three: In order to test the components of the egg, use the same indicator tests as seen above. The egg substitutes the standard solution and the other test conditions remain the same. Note the results from testing the membrane, yolk, and egg white. Describe the color changes and record the quantitative data on a comparison to the standard tests.
Standard Indicator Reaction
Egg Component
Membrane Egg White Yolk(egg cell) |
Benedict's Solution
Tests Glucose -Purple, not dark; 2 -Dark purple; 3 -Turned gray; 1 |
Iodine
Tests Starch -Turned red/brown; 2 -No reaction; 1 -Clay colored; 2 |
Biuret Reagent
Tests Protein -Light lavender; 2 -Lavender/blue; 2 -Mustard with purple color; 1 |
Sudan IV
Tests Fat -Pink/rose; 2 -Hue of pink; 1 -Still yellow; 1 |
Observations: The yolk probably contains a lot of protein and starch. The membrane's components are equally dispersed and the egg white holds a lot of sugars.
Scale for Numbers/Ratings: 0-3; Zero as no reaction and three as most color change. 0-No reaction; 1-Weak positive;2-Positive result;3-Very distinct posisitve
Scale for Numbers/Ratings: 0-3; Zero as no reaction and three as most color change. 0-No reaction; 1-Weak positive;2-Positive result;3-Very distinct posisitve
Conclusion: From this lab, we discovered tests used to figure out whether a solution contains proteins, carbohydrates, and fats(lipids). After receiving baseline results from compounds that contained the following nutrients, we were able to compare color changes and reactions of the standard solutions to the reactions of the egg components. From the observations, we were able to view the nutrients in the individual egg components. The standard indicators for carbohydrates were glucose and starch; the positive indicator for fat was oil; the positive indicator for protein was gelatin. For the egg components, view the observations and data chart above(different parts of egg test positive for different nutrients). I enjoyed individually finding the baseline instead of the textbook recording a preset chart indicating the color changes and reactions to compare. This extra step made the experiment feel more professional and accurate to our specific tests. Because the egg cracked a yolk.
One issue that occurred due to human error was the cross contamination of multiple tests. By the third day of testing, the labels on the pipets wiped off and it was challenging to distinguish which solution matched each test tube or pipet. Another problem when testing the egg components was the solidification of the yolk. This made mixing the indicator tests with the yolk more difficult and the reaction may have been less intense or delayed; therefore the results should have been a higher rank. Next time, we could be more clear about the labels on the pipets and thoroughly stir solutions before observing. By using indicator tests for cells, doctors could determine whether a person's cells contained the proper amounts of nutrients. Medical fields can test diverse medicine to discover which supplements were more effective for a person's cells.
One issue that occurred due to human error was the cross contamination of multiple tests. By the third day of testing, the labels on the pipets wiped off and it was challenging to distinguish which solution matched each test tube or pipet. Another problem when testing the egg components was the solidification of the yolk. This made mixing the indicator tests with the yolk more difficult and the reaction may have been less intense or delayed; therefore the results should have been a higher rank. Next time, we could be more clear about the labels on the pipets and thoroughly stir solutions before observing. By using indicator tests for cells, doctors could determine whether a person's cells contained the proper amounts of nutrients. Medical fields can test diverse medicine to discover which supplements were more effective for a person's cells.
Reflection:
I enjoyed individually finding the baseline instead of the textbook recording a preset chart indicating the color changes and reactions to compare. This extra step made the experiment feel more professional and accurate to our specific tests.One way my partner and I collaborated well was dividing the tasks equally and multitasking efficiently. While I performed one section of the experiment, she would be starting the next portion or preparing the solutions. We would also be able to start measuring liquids into different test tubes while waiting for the hot water bath to boil or for the reactions to occur. Cleaning up was also successful because everyone in our group participated in disposing of the solutions properly and wiping down the lab table.
One issue that arose from this experiment was the confusion of labels. Several of the test tubes and pipets had labels that smudged or got wiped off. This caused trouble when avoiding cross contamination; next time, we could organize the supplies better so materials don't get mixed up. Another problem was dealing with multiple different solutions concurrently and keeping the work area clean because of this. If we clearly separated each experiment of egg components and indicator tests, we could have maintained a more organized work station.
I enjoyed individually finding the baseline instead of the textbook recording a preset chart indicating the color changes and reactions to compare. This extra step made the experiment feel more professional and accurate to our specific tests.One way my partner and I collaborated well was dividing the tasks equally and multitasking efficiently. While I performed one section of the experiment, she would be starting the next portion or preparing the solutions. We would also be able to start measuring liquids into different test tubes while waiting for the hot water bath to boil or for the reactions to occur. Cleaning up was also successful because everyone in our group participated in disposing of the solutions properly and wiping down the lab table.
One issue that arose from this experiment was the confusion of labels. Several of the test tubes and pipets had labels that smudged or got wiped off. This caused trouble when avoiding cross contamination; next time, we could organize the supplies better so materials don't get mixed up. Another problem was dealing with multiple different solutions concurrently and keeping the work area clean because of this. If we clearly separated each experiment of egg components and indicator tests, we could have maintained a more organized work station.