Macromolecule Testing Lab
Evidence of Work
For our first project of the year, we tested foods and solutions for the presence of macromolecules like lipids, proteins, and carbohydrates. There was an indicator solution that showed whether or not each macromolecule was in what you were testing. For proteins, we used Biurets Solution which turned from blue to purple with a positive result. We used iodine for starch and it turned from yellow to black with a positive reaction and Benedicts Indicator was used to test for glucose because it turned an opaque orange or red from it's original light blue if there is glucose in what you are testing. There was no indicator solution for lipids because all we had to do was observe the contents of oils in comparion to water.
When testing for glucose we combined 2ml of the Benedicts solution with 2ml of the food for a reaction. For starch, we gently mixed 2ml of the food with 0.1ml of iodine to know whether there is starch in it. The lab for protein is mixing 2ml of the food sample with 0.75ml Biurets solution. We test for the presence of lipids by putting a drop of the food sample on a paper bag or towel and letting it dry to see how see through the spot is.
Content
Lipids: Made up of fatty acids and provide cell structure, insulation and long term energy storage.
Proteins: The monomer for proteins is amino acids and they function to repair muscle tissue. Enzymes are a protein that speed up chemical reactions.
Carbohydrates: Are made up of simple sugars or monosaccharides and are used to provide the body with energy.
Nucleic Acids: the monomer for nucleic acids are nucleotides and the function of nucleic acids is to store and carry genetic information.
When testing the maple cracker there were trace amounts of glucose because the Benedicts solution turned a dark green instead of orange or red. There was a lot of starch as the Iodine turned completely black, showing a positive reaction, and there was very little protein because the test didn't turn purple, but turned gray. The main contents of the walnut were starch and protein, with both having large positive reactions. There was minimal glucose and a pretty moderate amount of fat. The cracker had barely any fat. Our hypothesis that walnuts would have protein and lipids was mostly correct, but there was more starch than we thought.
Reflection
I think overall the project was very fun and went well. At the beginning we struggled to get the reactions we should have from the standard tests which should have shown each positive reaction perfectly. Despite this, when testing our actual food samples, everything went well and we were able to record accurate data. One reaction that was strange was that the Biurets solution turned gray instead of purple when testing the maple cracker. We do not have a proven reason for this though it may have just been a reaction to the other contents of the food. Some of the skills that I improved with this lab was collaboration and communication. This was because we had to keep track of everything we were testing and the instructions so we had to rely on other group members to know what they were doing as well. Something we actively improved on during the lab was time management because on the first day of testing sample solutions we didn't get to finish. As a response to this we were more conscious of our time when testing the food samples and utilized as many resources as we could to finish in time.