Organic Molecules Experiment

During the Organic Molecules experiment, four reagents were used to test for the presence of three of the four basic categories of Organic Molecules, carbohydrates, lips, and proteins, in control substances and Cheerios. For carbohydrates, I was testing, specifically, for the presence of reducing (polysaccharides) and non-reducing sugars (monosaccharides). Carbohydrates, both reducing and non-reducing, are important to the cell because they act as an energy source and are an important factor in building and the structure of important sugars like Ribose. Monosaccharides are important, specifically, because they are sources of nutrients to cells. An example of this would be glucose. (Campbell, 2014, 68) Non-reducing sugars, such as starch, serve as storage for cells and are hydrolyzed and broken down when sugars are needed for the cell. Some polysaccharides, such as cellulose, are used for structural purposes in cells. In plants, cellulose is

an important component to the tough cell walls in plant cells. (Campbell, 2014, 70) Lipids, which are very hydrophobic molecules, are important to cells because they store energy. (Campbell, 2014, 72) Lipids also play a major role in cell membranes. Proteins, out of all of the organic molecules, have the largest range of functions. In fact, proteins to the majority of the work in cells, accounting for more than approximately 50% of the dry mass in most cells, acting as enzymes (which are needed for every chemical reaction in the human body), transport, and even cell structure. (Campbell, 2014, 75)
The four reagents that I used to test for the presence of these organic molecules in my control substances and cheerios were Benedict’s, Lugol’s, Beta Carotene, and Biuret’s. Each reagent caused a chemical reaction that turned the substances being tested, a different color, thus allowing me to determine the presence, or lack there-of, of the organic molecules in question. Benedict’s, which tests for monosaccharides, works by reacting with the carbohydrate molecules and producing a red-brown precipitate consisting of copper (I) oxide. Lugol’s, which tests for polysaccharides, produces a black-blue color when it gets stuck in the beta coils of starch. Beta Carotene, which tests for lipids, works by simply dissolving into a solution and turning it orange. Biuret’s, which tests for proteins, works by reacting with polypeptides, peptide bonds, thus producing a purple-blue color.
My hypothesis, after testing the control substances, was that Cheerios would test positive for carbohydrates, lipids, and protein because I know that Cheerios contain a healthy, recommended amount of protein, carbohydrates, and fats, which is one reason they are believed to be such a great food.
In each experiment, including the one using my food, distilled water was always used for the control.
To begin my experimentation, I created a stock solution, which would be used in each test.

I used Cheerios, distilled water, and a pestle and mortar. I ground the Cheerios until they had a fine, sand-like texture and consistency. I then added distilled water and mixed until I was left with a thin, runny solution, that was beige in color. Once I had the stock solution made, I was able to perform my first experiment, beginning with Benedict’s reagent. For this experiment I used a hot plate, beaker, and three test tubes, one labeled + (positive control), - (negative control), and Cheerios. Two milliliters of each solution was then added to the tubes they were labeled to go into. In this experiment, the positive control was a glucose solution. I then added two milliliters of Benedict’s reagent to each tube. Once a boiling bath had been made using water, the beaker, and the hot plate, each of the three test tubes were places, sitting upwards, into the boiling bath. A timer was set for three minutes, and I recorded the color

changes.
Next, I used Lugol’s reagent to test my substance. I used three test tubes, again, also labeled + (positive control), - (negative control), and Cheerios. The positive control for this experiment was a starch solution. I added one milliliter of each substance to the appropriate, labeled tube. I then added several drops of Lugol’s reagent to each tube, gently shook each, and recorded the color change.
The next experiment I did used the Beta carotene pigment. As in the last two experiments, three test tubes were used and labeled the same way. In this experiment, the positive control was oil. I added two milliliters of each solution to its respective, labeled tube and then a drop of Beta carotene to each. I recorded the solubility.
For the last experiment, I used Biuret’s reagent. As in the last three experiments, three test tubes were used and labeled the same way. In this experiment, the positive control was albumin. I added two milliliters of each substance to its respective, labeled tube. I then added two milliliters of Biuret’s reagent to each tube and recorded the color changes.
Results of My Organic Molecule Experiment
Benedict’s Lugol’s β-carotene Biuret’s
Water - - - -
Glucose Solution + - N/A N/A
Starch Solution - + N/A N/A
Oil N/A N/A + N/A
Albumin Solution N/A N/A N/A +
Cheerios + + - +
(Note: Any place “N/A” is marked on this table, a test was not completed using this reagent/solution combination)
During the experiment using Benedict’s reagent the Cheerios solution turned from beige to brown-red in color which was similar to the color of the positive control in this test; therefore the solution contained monosaccharide molecules. During the experiment using Lugol’s reagent the solution turned from beige to black in color which was similar to the color of the positive control in the test; therefore the Cheerios solution contained polysaccharide molecules. During the experiment using the Beta carotene pigment, the pigment did not seem to dissolve at all in the Cheerios solution. It only sat at the top; therefore the Cheerios solution did not seem to include lipid molecules. During the experiment using Biuret’s reagent the Cheerios turned from beige to violet in color which was similar to the color of the positive control; therefore the solution must contain protein molecules.
My original hypothesis was that my Cheerios would test positive in each of the experiments that I’d be preforming, but from the results of my experimentation, I had gathered information that would’ve lead me to believe my Cheerios contained protein, monosaccharide, and polysaccharide molecules. However, based on this experiment alone, I was left to believe that there were no lipids present in my Cheerios. Although my solution tested negative for lipids, I believe the only reason this happened was because there was too much water in it. Another flaw in my experiment was that, while I am aware of the ingredients of Cheerios, I don’t really know if my solution truly contained Cheerios in the first place because I was not given the opportunity to see and observe the original box and packaging they came in. Either way, I do know that almost all processed foods have some percentage of fat, and therefore, lipids would be present. I also checked the official website for the Cheerios brand cereal, and I noticed that they all contained some percentage of fat. The only solution to this flaw that I can come up with, would be to use a different test to test for the presence of lipids in my solution. I strongly believe that the insolubility of the beta carotene in water, along with the high percentage of water in my solution, prevented me from being able to get a real result in that test. If I were to design a new experiment to test for lipids, using the Beta carotene again, I would use less water, and I would ground my Cheerios to a finer texture. I also would use more Beta carotene and I would shake the solution, with the Beta carotene added to it, for a least a minute. This way, it would’ve been able to react with more of the Cheerio component of the solution, and perhaps, change colors.
Overall, the cellular activity going on in our bodies require the nutrients that come from what we ingest. As a result of this, we need to be mindful of what we are and are not eating. This way we can be sure that we’re feeding ourselves the right, and right amount, of nutrients our bodies need.