Finding Macromolecules in Food
Priyal Patel

Abstract: This experiment was conducted in order to find the presence of a certain macromolecule in a food sample. This was done by using different reagents that would indicate a certain macromolecule present by a color change. The data presented within this lab shows that each reagent gave a color change to a solution, showing whether or not the macromolecule was present in the food item. Each result depended on the actual nutritional value of the food item and the test proved if the food sample contained the macromolecule tested for. From conducting this experiment, it is clear to see that each test provided results to whether or not the substance contained the macromolecule tested for.
Introduction & Hypothesis: In this lab experiment, different tests were carried out to reveal the presence of one out of the three possible macromolecules. The macromolecules tested for were carbohydrates, lipids, and proteins. In biology, there are a total of four macromolecules: carbohydrates, lipids, proteins, and nucleic acids. Each macromolecule is an organic compound, which means that they all contain carbon, hydrogen, and oxygen. These four macromolecules all exist in living organisms, (Notes sheet, 2014). Carbohydrates are sugars, which is the body’s primary source of energy. They exist in two specific types: monosaccharides and polysaccharides. Lipids are molecules that serve as long-term energy to the body, which are commonly known as fats (Lab handout, 2014). They serve to protect and come in many different varieties, like in plant oil. Proteins are made up of amino acids, which are the building blocks of proteins. There are twenty amino acids present in nature, and a variety of these amino acids can be found in certain foods like milk and meat (Lab handout, 2014). The final macromolecule is nucleic acid; it was not used in this lab. They make up DNA and RNA which are important to cellular regulation.
The specific purpose of this study was to test for the presence of a certain macromolecule in food samples. This was done by conducting certain tests with a reagent. (Lab handout, 2014). A reagent is a substance used for analysis in a reaction (Merriam-Webster, 2014). Each macromolecule tested in this lab had its own reagent that would show whether the certain macromolecule was present or not. To test for proteins, the Biuret reagent was used. To see if there were proteins present, a positive result would be that the solution had a pink/purple color change. For the lipids, the Sudan red reagent was used. For a positive indication, the solution would have a red color. To also test for lipids, the grease test was used. After leaving food samples on a paper bag for a few minutes, if they had translucent spots, then lipids were present. Finally, for carbohydrates the Benedict reagent was used, if positive the solution would have an orange color change. Each of these tests had one test with the food sample, and another test with water, which was the control. The control allowed for observation and change that occurred with the experimental test. The hypothesis for this lab was that an observable change would indicate the presence of a certain macromolecule.

Materials:
These are the materials that were used in this lab in room 643 at Lowell High School:

Methods:
This lab was carried out in a sequence of steps. The first test that was carried out was the Grease spot test. First, four squares were drawn onto a paper bag. The food items, potato, cheese, and chips were each placed in one square. In the first spot water was placed as the control. After having waiting for a few minutes, each spot was checked for "lipid spots" areas that were darker than the paper bag. Data was observed and then recorded on the results table.
The next test was for monosaccharides, two mL of corn syrup and water were placed into test tubes. After the corn syrup had settled to the