Lab 2A: Dissecting a Cell & Examining its Components
Date: August 25, 2014
Purpose: What are positive indicator tests for proteins, carbohydrates, and fats? Do parts of an egg test positive for protein, carbohydrate, and/or fat?
Purpose: What are positive indicator tests for proteins, carbohydrates, and fats? Do parts of an egg test positive for protein, carbohydrate, and/or fat?
Materials:
- Eggs - Beaker, 250 mL - White vinegar - Plastic wrap - Slotted Spoon - Sodium chloride - Distilled water - Sudan IV Solution |
- Beaker, 100 mL
- Pipette, 5 mL - Pipette pump, green - Tube, glass, 13 x 100 mm - Peg racks for 13 x 100 mm tubes - Glucose (dextrose) - Benedict's Solution - Hot plate stirrer - Scalpel handles #4, blades #22 |
- Test tube holder
- Starch, soluble - Lugol's Iodine Solution - Vortex mixer - Gelatin - Sodium hydroxide - Cupric sulfate 5-hydrate - Oil - trays, plastic |
Procedure: (Part I - Separating Cell Structures)
1. Place an uncooked egg into a beaker with white vinegar. Cover beaker with plastic wrap. Let it sit for at least 24 hours.
2. After 24 - 48 hours, the shell should have dissolved because acetic acid breaks calcium carbonate into water and carbon dioxide.
3. Using slotted spoon, pick up the egg. Rinse.
4. Feel the outer membranes of the cell.
5. Place the egg in a beaker of 5% NaCl solution for 24 hours. Describe the appearance of egg.
6. Rinse again. Then place the egg in a beaker of distilled water for 24 hours. Describe the appearance of egg.
7. Slice open the egg's membranes to get to the egg cell, and let the egg white drip through the slots of the spoon into a 100-mL beaker.
8. Place the egg yolk (egg cell with a clear, flimsy cell membrane around it) into another beaker, and set aside the egg membranes.
1. Place an uncooked egg into a beaker with white vinegar. Cover beaker with plastic wrap. Let it sit for at least 24 hours.
2. After 24 - 48 hours, the shell should have dissolved because acetic acid breaks calcium carbonate into water and carbon dioxide.
3. Using slotted spoon, pick up the egg. Rinse.
4. Feel the outer membranes of the cell.
5. Place the egg in a beaker of 5% NaCl solution for 24 hours. Describe the appearance of egg.
6. Rinse again. Then place the egg in a beaker of distilled water for 24 hours. Describe the appearance of egg.
7. Slice open the egg's membranes to get to the egg cell, and let the egg white drip through the slots of the spoon into a 100-mL beaker.
8. Place the egg yolk (egg cell with a clear, flimsy cell membrane around it) into another beaker, and set aside the egg membranes.
Procedure: (Part II - Testing Standard Solutions)
Monosaccharide Indicator Standard Test:
1. Test for glucose: 2 mL of a 2% glucose solution + 2 mL of Benedict's solution. Heat for 2 minutes in 100 mL of water in a 250-mL beaker at 100 degrees Celsius. Record all color changes.
2. Test for water (negative control): 2 mL of deionized water + 2 mL of Benedict's solution. Heat for 2 minutes in a boiling hot water bath (dimensions above) and record all color changes.
Starch Indicator Standard Test:
1. Test for Starch: 2 mL of well-mixed starch suspension with 0.25 mL of Lugol's iodine. Mix. Don't heat. Record color change.
2. Test for water (negative control): In a test tube, mix 2 mL of deionized water with 0.25 mL of Lugol's iodine. Mix. Don't heat. Record color change.
Protein Indicator Standard Test:
1. Test for protein: 2 mL of gelatin solution + Biuret Reagent and gently mix. Mix well. Record color change after 30 seconds.
2. Test for water (negative control): 2 mL of deionized water in a test tube + Biuret Reagent, and gently mix well. Record color change after 30 seconds.
Lipid Indicator Standard Test:
1. Test for Lipids: Add Sudan IV to the oil. Mix well.
2. Test for water: Add Sudan IV to the water. Mix well.
Monosaccharide Indicator Standard Test:
1. Test for glucose: 2 mL of a 2% glucose solution + 2 mL of Benedict's solution. Heat for 2 minutes in 100 mL of water in a 250-mL beaker at 100 degrees Celsius. Record all color changes.
2. Test for water (negative control): 2 mL of deionized water + 2 mL of Benedict's solution. Heat for 2 minutes in a boiling hot water bath (dimensions above) and record all color changes.
Starch Indicator Standard Test:
1. Test for Starch: 2 mL of well-mixed starch suspension with 0.25 mL of Lugol's iodine. Mix. Don't heat. Record color change.
2. Test for water (negative control): In a test tube, mix 2 mL of deionized water with 0.25 mL of Lugol's iodine. Mix. Don't heat. Record color change.
Protein Indicator Standard Test:
1. Test for protein: 2 mL of gelatin solution + Biuret Reagent and gently mix. Mix well. Record color change after 30 seconds.
2. Test for water (negative control): 2 mL of deionized water in a test tube + Biuret Reagent, and gently mix well. Record color change after 30 seconds.
Lipid Indicator Standard Test:
1. Test for Lipids: Add Sudan IV to the oil. Mix well.
2. Test for water: Add Sudan IV to the water. Mix well.
Procedure: (Part III - Molecular Composition of Egg Components)
1. Conduct each indicator test (Part II) but substitute each egg component to be tested for sugar, starch, protein, or fat.
2. Record results of testing the egg membranes: the yolk (cell cytoplasm) and egg white.
3. Give a numerical value to each test result using the following scale: [ 3 = very strong/positive test, 2 = strong/positive test, 1 = weak/positive test, 0 = no color change in indicator/negative ]
1. Conduct each indicator test (Part II) but substitute each egg component to be tested for sugar, starch, protein, or fat.
2. Record results of testing the egg membranes: the yolk (cell cytoplasm) and egg white.
3. Give a numerical value to each test result using the following scale: [ 3 = very strong/positive test, 2 = strong/positive test, 1 = weak/positive test, 0 = no color change in indicator/negative ]
Results
Part I:
1. Calcium Carbonate + Vinegar --> Water + Carbon Dioxide : The hard outside of the shell dissolved into the vinegar, leaving just the thin membrane of the egg.
2. Egg + Salt Water : According to the scientific laws, areas of higher pressure diffuse to areas of lower pressure. In the experiment, this occurred during this particular procedure. The salt water passed through the membrane into the egg, while the regular water inside left the egg. Because of this diffusion, the egg appeared smaller.
3. Egg + Water: When the egg is doused back in water, the saltwater solution inside the egg returns to outside the egg. The regular water in the beaker enters the egg, causing it to be bigger and bloated. This explains why when we cut a slit into the membrane, the egg contents seemed to burst outward.
1. Calcium Carbonate + Vinegar --> Water + Carbon Dioxide : The hard outside of the shell dissolved into the vinegar, leaving just the thin membrane of the egg.
2. Egg + Salt Water : According to the scientific laws, areas of higher pressure diffuse to areas of lower pressure. In the experiment, this occurred during this particular procedure. The salt water passed through the membrane into the egg, while the regular water inside left the egg. Because of this diffusion, the egg appeared smaller.
3. Egg + Water: When the egg is doused back in water, the saltwater solution inside the egg returns to outside the egg. The regular water in the beaker enters the egg, causing it to be bigger and bloated. This explains why when we cut a slit into the membrane, the egg contents seemed to burst outward.
Part II and Part III Data Tables:
lab_2a.gdoc | |
File Size: | 0 kb |
File Type: | gdoc |
Data Analysis / Conclusion:
Positive indicator tests for proteins, fats, and carbohydrates are done through comparing solutions with and without the control. We can tell if the solution tests positive for a certain component depending on its color change. We first tested the positive and negative controls of glucose, carbohydrates, proteins, and fats. We took the data from that experiment. Then, we conducted the same experiments on the egg parts and recorded color change. By comparing that piece to the previous data, we were able to tell if it tested positive or negative.
In the end, we concluded that the egg cell did test positive for several of the above components.
1. The egg whites tested positive for all components. It tested weakly for glucose and fat, but very strongly for protein and starch.
2. The egg yolk tested weakly for most of the components, like glucose and starch. The yolk tested negative for protein, but strongly positive for lipids.
3. The egg membrane tested positive for all components. It tested weakly for glucose, but strongly for protein and fat. Though not as prevalent, there was still a significant indication of starch in the membrane.
Some variables may have been temperature in the hot water bath. We did not measure the temperature of the water before putting the glucose test in, which may have caused slight variance in the test. We could fix this by specifically using a thermometer before using the hot water bath.
In connection to this experiment, there are several indicator tests that we use in the real world. People use drug indicator tests, and tests that indicate sugar levels for people with diabetes. Other examples include pH sticks, which are indicators for either acidic or basic solutions.
Positive indicator tests for proteins, fats, and carbohydrates are done through comparing solutions with and without the control. We can tell if the solution tests positive for a certain component depending on its color change. We first tested the positive and negative controls of glucose, carbohydrates, proteins, and fats. We took the data from that experiment. Then, we conducted the same experiments on the egg parts and recorded color change. By comparing that piece to the previous data, we were able to tell if it tested positive or negative.
In the end, we concluded that the egg cell did test positive for several of the above components.
1. The egg whites tested positive for all components. It tested weakly for glucose and fat, but very strongly for protein and starch.
2. The egg yolk tested weakly for most of the components, like glucose and starch. The yolk tested negative for protein, but strongly positive for lipids.
3. The egg membrane tested positive for all components. It tested weakly for glucose, but strongly for protein and fat. Though not as prevalent, there was still a significant indication of starch in the membrane.
Some variables may have been temperature in the hot water bath. We did not measure the temperature of the water before putting the glucose test in, which may have caused slight variance in the test. We could fix this by specifically using a thermometer before using the hot water bath.
In connection to this experiment, there are several indicator tests that we use in the real world. People use drug indicator tests, and tests that indicate sugar levels for people with diabetes. Other examples include pH sticks, which are indicators for either acidic or basic solutions.
Reflection:
I thought the entire procedure was very interesting. The chemical reaction between the calcium carbonate and vinegar was cool to see occur. It was a great lab that let me become accustomed to much of the lab materials: the pipettes, vortex, and hot plates, for example. It was intriguing to cut open the egg membrane and test just what kinds of components were in each section of the egg. I'd always thought that the egg yolk was filled with protein, but this experiment proved otherwise: the yolk is the fatty part of the egg, testing strongly positive for lipids.
My partner for this lab was Natalie Mansergh, and we worked really well together. The collaboration aspect wasn't a problem for us; we were both engaged, shared jobs appropriately, and managed our time well. As mentioned in the Conclusion, the only other thing I would want to change was the accuracy of the hot water bath temperature.
I thought the entire procedure was very interesting. The chemical reaction between the calcium carbonate and vinegar was cool to see occur. It was a great lab that let me become accustomed to much of the lab materials: the pipettes, vortex, and hot plates, for example. It was intriguing to cut open the egg membrane and test just what kinds of components were in each section of the egg. I'd always thought that the egg yolk was filled with protein, but this experiment proved otherwise: the yolk is the fatty part of the egg, testing strongly positive for lipids.
My partner for this lab was Natalie Mansergh, and we worked really well together. The collaboration aspect wasn't a problem for us; we were both engaged, shared jobs appropriately, and managed our time well. As mentioned in the Conclusion, the only other thing I would want to change was the accuracy of the hot water bath temperature.