Lab 2a: Dissecting a Cell and Examining Its Components
Purpose: To find positive indicator tests for proteins, carbohydrates, and fats. To see if parts of an egg test positive for proteins, carbohydrates, and fats. Hypothesis: If the color of a protein, carbohydrate, or fat solution is a distinct, clear color, than the indicator test is positive rather than a negative one. Materials:
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Procedure:
Part I: Separating Cell Structures
1. Label and cover a beaker of white vinegar will an uncooked egg with plastic wrap. Let sit for 24 to 48 hours for shell to dissolve.
2. The shell should have dissolved in the acetic acid (vinegar) after left for 24 to 48 hours. With a slotted spoon, pick up the egg and clean off the vinegar. A chemical reaction has occurred.
3. While feeling the outer membranes of the cell, notice how it resembles a cell membrane. This outer membrane is different from the yolk's membrane. The outer membrane is thin, flexible, and permeable to some substances. Leave the egg for 24 hours in a beaker filled with 5% of NaCl solution and describe its appearance.
4. After rinsing the egg with water, put the egg in a beaker of distilled water for 24 hours. What was the cause for the difference in appearance?
5. To take out the egg cell, cut the egg's membrane, and let the egg white drip through the slots of the spoon into a 100 mL beaker. Do your best to get all the egg white into the beaker without express bursting the yolk (egg cell with clear, unstable cell membrane around it).
6. Put the egg yolk in another beaker. Leave the egg membranes aside.
Part II:
Test four solutions of known composition (positive controls or standards) with appropriate indicator solution. Record data about standards of monosaccharides, starch, proteins, and lipids in table.
Part I: Separating Cell Structures
1. Label and cover a beaker of white vinegar will an uncooked egg with plastic wrap. Let sit for 24 to 48 hours for shell to dissolve.
2. The shell should have dissolved in the acetic acid (vinegar) after left for 24 to 48 hours. With a slotted spoon, pick up the egg and clean off the vinegar. A chemical reaction has occurred.
3. While feeling the outer membranes of the cell, notice how it resembles a cell membrane. This outer membrane is different from the yolk's membrane. The outer membrane is thin, flexible, and permeable to some substances. Leave the egg for 24 hours in a beaker filled with 5% of NaCl solution and describe its appearance.
4. After rinsing the egg with water, put the egg in a beaker of distilled water for 24 hours. What was the cause for the difference in appearance?
5. To take out the egg cell, cut the egg's membrane, and let the egg white drip through the slots of the spoon into a 100 mL beaker. Do your best to get all the egg white into the beaker without express bursting the yolk (egg cell with clear, unstable cell membrane around it).
6. Put the egg yolk in another beaker. Leave the egg membranes aside.
Part II:
Test four solutions of known composition (positive controls or standards) with appropriate indicator solution. Record data about standards of monosaccharides, starch, proteins, and lipids in table.
Monosaccharide Indicator Standard Test:
1. In test tube, combine 2 mL of 2% glucose solution with 2 mL Benedict's Solution. Heat the 100 mL test tube at 100 degrees Celsius in a 250 mL beaker for 2 minutes by placing it in a boiling hot water bath. Write in table color changes and amount of time it takes to change a certain color.
2. Combine 2 mL of the Benedict's Solution with 2 mL of deionized water. Place the 100 mL test tube in a 100 degrees Celsius 250 mL hot water bath for two minutes. Record changes in color and the time the liquid changed colors.
Starch Indicator Test:
1. Combine 2 mL of well-mixed starch suspension with 0.25 mL of Lugol's iodine. Gently swish to mix. Record changes in color. Do not heat.
2. Combine 2 mL of deionized water with 0.25 mL of Lugol's iodine. Gently swish to mix. Record color changes. Do not heat.
Protein Indicator Standard Test:
1. Put 2 mL of gelatin solution in test tube. Add 1 mL of the Biuret reagent. Mix well. Record color change after 30 seconds.
2. Put 2 mL of deionized water and 1 mL Biuret reagent in test tube. Mix well and record changes in color after 30 seconds.
Lipid Indicator Standard Test:
1. Mix 2 mL of oil and 60 uL of Sudan IV in test tube. This shows lipids. Record color change.
2. Mix 2 mL of deionized water and 60 uL of Sudan IV in a test tube. Record color change.
- Use a micropipette to measure 60 uL of Sudan IV.
Part III: Molecular Composition of Egg Components
1. Conduct each experiment above but substitute each egg component to be tested for sugar, starch, protein, or fat. All conditions/volumes are the same.
2. For the four molecules, record the testing results of yolk(cell cytoplasm), egg membranes, and egg white.
3. Based on comparison from standard test, use number system below to evaluate results. Include color change description.
The Presence and Relative Amount of Organic Materials Found in Egg:
Key: 3 = very strong/positive test; 2 = strong positive test; 1 = weak/positive test; 0 = no color change in indicator/negative
1. In test tube, combine 2 mL of 2% glucose solution with 2 mL Benedict's Solution. Heat the 100 mL test tube at 100 degrees Celsius in a 250 mL beaker for 2 minutes by placing it in a boiling hot water bath. Write in table color changes and amount of time it takes to change a certain color.
2. Combine 2 mL of the Benedict's Solution with 2 mL of deionized water. Place the 100 mL test tube in a 100 degrees Celsius 250 mL hot water bath for two minutes. Record changes in color and the time the liquid changed colors.
Starch Indicator Test:
1. Combine 2 mL of well-mixed starch suspension with 0.25 mL of Lugol's iodine. Gently swish to mix. Record changes in color. Do not heat.
2. Combine 2 mL of deionized water with 0.25 mL of Lugol's iodine. Gently swish to mix. Record color changes. Do not heat.
Protein Indicator Standard Test:
1. Put 2 mL of gelatin solution in test tube. Add 1 mL of the Biuret reagent. Mix well. Record color change after 30 seconds.
2. Put 2 mL of deionized water and 1 mL Biuret reagent in test tube. Mix well and record changes in color after 30 seconds.
Lipid Indicator Standard Test:
1. Mix 2 mL of oil and 60 uL of Sudan IV in test tube. This shows lipids. Record color change.
2. Mix 2 mL of deionized water and 60 uL of Sudan IV in a test tube. Record color change.
- Use a micropipette to measure 60 uL of Sudan IV.
Part III: Molecular Composition of Egg Components
1. Conduct each experiment above but substitute each egg component to be tested for sugar, starch, protein, or fat. All conditions/volumes are the same.
2. For the four molecules, record the testing results of yolk(cell cytoplasm), egg membranes, and egg white.
3. Based on comparison from standard test, use number system below to evaluate results. Include color change description.
The Presence and Relative Amount of Organic Materials Found in Egg:
Key: 3 = very strong/positive test; 2 = strong positive test; 1 = weak/positive test; 0 = no color change in indicator/negative
Data and Results:
Part I Data and Results:
Part II Data and Results:
Part III Data and Results:
Data Analysis:
1. There are many proteins, carbohydrates, and fats positive indicator tests. Usually the positive indicator test was cloudier and less bright than the negative indicator test. For example, in the positive protein test, the solution was a foggy purple while its negative test was a clear indigo. In the positive lipids test, the solution was a cloudy orange while its negative test was a clear red. In the monosaccharide test, the solution changing different colors while its negative test stayed one distinct color when it was heated up. In the positive starch test, the solution was a brown while its negative test was a clearer orange. This pattern was common amongst the positive and negative standard indicator tests.
2. The egg whites tested positive for the Monosaccharide, or glucose, test, but it tested negative for the lipid, protein, and starch indicator test. The yolk was positive for the Monosaccharide, protein, and lipid test, but it tested negative for the starch test. The egg's membrane was positive for the Monosaccharide, starch, and lipids test, but it tested negative for the protein test. As you can see, the different components and compositions of the egg reacted differently: positive or negative.
3. There was definitely room for experimental error in this lab. To start with, all of our data was subjective. My partner and I had to use our own judgment to see the color change after mixing or heating. Obviously, we could have looked at a result as if it were positive when it was actually negative. Secondly, we used many test tubes for this experiment. The class before labeled the pipettes, but they could have been carelessly used. There was a possibility for cross contamination that could have skewed the results of positive or negative. Lastly, the egg took great care to separate. It was not perfect and some of the different egg parts (membrane, yolk, and egg white) mixed slightly. This also could have affected the tests about the egg's composition.
4. This lab could use some help. First of all, the order could be presented in a different manner. By following the lab manual, my partner and I kept cleaning off tubes then using them again later. In terms of efficiency and organization, all the Benedict's solution or Sudan IV solution tests should have been listed together. Secondly, the lab should have warned to have a space where dropping solutions on it would not matter. My papers were spotted with the dark Lugol's iodine because I was unaware of the mess. Lastly, this lab should have extended to a different type of cell model. This even be another type of food. This would help us see the different qualities of different cells.
5. Indicator tests are used all across the world. Many people use this type of test to measure a specific amount of a contaminant in a substance. Some applications of indicator tests include doctors checking for signs of diabetes in your urine, drug tests, and waste materials in water. All of these tests rely on the scientist to observe any signals for the contaminant in the solution.
1. There are many proteins, carbohydrates, and fats positive indicator tests. Usually the positive indicator test was cloudier and less bright than the negative indicator test. For example, in the positive protein test, the solution was a foggy purple while its negative test was a clear indigo. In the positive lipids test, the solution was a cloudy orange while its negative test was a clear red. In the monosaccharide test, the solution changing different colors while its negative test stayed one distinct color when it was heated up. In the positive starch test, the solution was a brown while its negative test was a clearer orange. This pattern was common amongst the positive and negative standard indicator tests.
2. The egg whites tested positive for the Monosaccharide, or glucose, test, but it tested negative for the lipid, protein, and starch indicator test. The yolk was positive for the Monosaccharide, protein, and lipid test, but it tested negative for the starch test. The egg's membrane was positive for the Monosaccharide, starch, and lipids test, but it tested negative for the protein test. As you can see, the different components and compositions of the egg reacted differently: positive or negative.
3. There was definitely room for experimental error in this lab. To start with, all of our data was subjective. My partner and I had to use our own judgment to see the color change after mixing or heating. Obviously, we could have looked at a result as if it were positive when it was actually negative. Secondly, we used many test tubes for this experiment. The class before labeled the pipettes, but they could have been carelessly used. There was a possibility for cross contamination that could have skewed the results of positive or negative. Lastly, the egg took great care to separate. It was not perfect and some of the different egg parts (membrane, yolk, and egg white) mixed slightly. This also could have affected the tests about the egg's composition.
4. This lab could use some help. First of all, the order could be presented in a different manner. By following the lab manual, my partner and I kept cleaning off tubes then using them again later. In terms of efficiency and organization, all the Benedict's solution or Sudan IV solution tests should have been listed together. Secondly, the lab should have warned to have a space where dropping solutions on it would not matter. My papers were spotted with the dark Lugol's iodine because I was unaware of the mess. Lastly, this lab should have extended to a different type of cell model. This even be another type of food. This would help us see the different qualities of different cells.
5. Indicator tests are used all across the world. Many people use this type of test to measure a specific amount of a contaminant in a substance. Some applications of indicator tests include doctors checking for signs of diabetes in your urine, drug tests, and waste materials in water. All of these tests rely on the scientist to observe any signals for the contaminant in the solution.
Conclusion:
If the color of a protein, carbohydrate, or fat solution is foggy versus clear, than it is a positive indicator test rather than a negative one.
If the color of a protein, carbohydrate, or fat solution is foggy versus clear, than it is a positive indicator test rather than a negative one.
Reflection:
1. I found the egg composition and components test in the Part III procedure most interesting. The yolk always gave a bright color while the membrane and the egg white produced a gray color. Sometimes it was opposite though. For example, in the lipid test, the egg white tested negative, but the egg's yolk tested positive . The different compositions of the egg's membrane, yolk, and egg whites affected their outcomes dramatically: positive or negative. Another interesting part of the lab was when the egg was soaked in the vinegar and its shell dissolved. In the sodium chloride solution, the white remnants of the shell could be rubbed off due to a chemical reaction between calcium carbonate (shell) and carbonic acid (vinegar). The egg looked transparent now. The egg decreased in size, but increased when it was soaked in deionized water. When we cut the egg, it burst forcefully due to the immense amount of pressure with that large amount of water in the egg. This was fascinating to see how the cells move in different surrounding environments and how the egg and its components reacted.
2. Mikayla DeBarros was my partner in this lab. We have been friends since kindergarten and we have never had a science class together It was nice to finally collaborate with each other after all these years. It was pretty smooth going since both of us are interested in biology. I would give Mikayla a nineteen in leadership because we both were lead one another some where down the rode, but not one of us stood out as the leader. Mikayla received a nineteen also in cooperation because she was very helpful to me when I was moving slowly around the lab in my boot for my ankle, but she was tired on some days and was less focused. I'm sure I was like that also. Mikayla deserves a twenty in attitude and demeanor because she always acted and conducted the experiment with obedience. In facilitation and mediation, Mikayla gets a twenty because there were never any instances when we need a liaison. Lastly, Mikayla earns a twenty in empathy. Like I said, she was always ready to aid me when I was hurt without any questions. All in all, I thought that we worked well as lab partners.
3. Next time we do this lab, I would be more efficient about it. since we were running out of time, Mikayla and I had to divide and conquer for the egg components test. We started working together, but we would never have finished in time. Because we were so rushed in the end, I never got time to appreciate the lab and investigate more. In the future, I will know to take advantage of the time given to finish the lab together in a timely matter. This way we can work together and learn more about the lab.
1. I found the egg composition and components test in the Part III procedure most interesting. The yolk always gave a bright color while the membrane and the egg white produced a gray color. Sometimes it was opposite though. For example, in the lipid test, the egg white tested negative, but the egg's yolk tested positive . The different compositions of the egg's membrane, yolk, and egg whites affected their outcomes dramatically: positive or negative. Another interesting part of the lab was when the egg was soaked in the vinegar and its shell dissolved. In the sodium chloride solution, the white remnants of the shell could be rubbed off due to a chemical reaction between calcium carbonate (shell) and carbonic acid (vinegar). The egg looked transparent now. The egg decreased in size, but increased when it was soaked in deionized water. When we cut the egg, it burst forcefully due to the immense amount of pressure with that large amount of water in the egg. This was fascinating to see how the cells move in different surrounding environments and how the egg and its components reacted.
2. Mikayla DeBarros was my partner in this lab. We have been friends since kindergarten and we have never had a science class together It was nice to finally collaborate with each other after all these years. It was pretty smooth going since both of us are interested in biology. I would give Mikayla a nineteen in leadership because we both were lead one another some where down the rode, but not one of us stood out as the leader. Mikayla received a nineteen also in cooperation because she was very helpful to me when I was moving slowly around the lab in my boot for my ankle, but she was tired on some days and was less focused. I'm sure I was like that also. Mikayla deserves a twenty in attitude and demeanor because she always acted and conducted the experiment with obedience. In facilitation and mediation, Mikayla gets a twenty because there were never any instances when we need a liaison. Lastly, Mikayla earns a twenty in empathy. Like I said, she was always ready to aid me when I was hurt without any questions. All in all, I thought that we worked well as lab partners.
3. Next time we do this lab, I would be more efficient about it. since we were running out of time, Mikayla and I had to divide and conquer for the egg components test. We started working together, but we would never have finished in time. Because we were so rushed in the end, I never got time to appreciate the lab and investigate more. In the future, I will know to take advantage of the time given to finish the lab together in a timely matter. This way we can work together and learn more about the lab.