1. You are given unlabeled vials containing samples of a carbohydrate, a lipid, and a protein. Design an experiment that will allow you to distinguish which vial contains which macromolecule.
To distinguish the vial containing each macromolecule (carbohydrate, lipid, and protein), you can conduct a series of experiments that target the unique properties of each type of macromolecule. Here is a suggested experiment design:
1. Benedict's test for carbohydrates:
- Take a small sample from each vial and add it to separate test tubes.
- Add Benedict's solution to each test tube.
- Place the test tubes in a water bath and heat them for a few minutes.
- Observe the color change in each test tube. Benedict's solution turns different shades of green, yellow, orange, or red depending on the presence of reducing sugars found in carbohydrates. The intensity of the color can indicate the amount of carbohydrates present.
2. Sudan III test for lipids:
- Take a small sample from each vial and add it to separate test tubes.
- Add a few drops of Sudan III stain or Sudan Red dye to each test tube.
- Mix the contents by shaking gently and let them sit for a few minutes.
- Observe the color change in each test tube. Sudan III stains lipids a bright red or orange, allowing for the identification of lipids based on the color intensity.
3. Biuret test for proteins:
- Take a small sample from each vial and add it to separate test tubes.
- Add a few drops of a dilute copper sulfate solution to each test tube.
- Mix the contents by shaking gently and then add a few drops of sodium hydroxide solution to each test tube.
- Observe the color change in each test tube. The presence of proteins will result in a violet or purple color upon reacting with the copper ions in the biuret reagent.
By performing these tests, you will be able to identify the vial containing carbohydrates by its positive Benedict's test, the vial containing lipids by its positive Sudan III test, and the vial containing proteins by its positive Biuret test.