The macromolecule lab taught us how to set up a comparison to determine what a positive and negative test for a macromolecule looked like. Afterwards we used our positively tested samples as comparisons to determine whether or not the unknown food items that were brought in were positive for any of the four macromolecules.
In this lab we conducted an experiment in order to determine what macromolecules where present in foods and how to distinguish between a positive test and a negative test. We each brought in an unknown food samples and used our positive test samples to determine whether or not the food we brought in contained any of the four macromolecules.
If there is a color change with any of the testing samples of the four macromolecules we can conclude that is different than the original color in the distilled water of the four macromolecules we can conclude that reagents successfully showed us a positive sample. When testing our food we can determine that if a color matches our positive reaction or is relatively close to it that the food contains amounts of the macromolecules that we were testing.
Mortar and pedestal
Benedict, Iodine, Sudan red, and Biuret
Test tube holders
Lays Cheddar and Sour Cream chips
Test tube rack
We first took a total of eight test tubes filling one half with ten milligrams of distilled water and the other half with our macromolecule substances. We began with the sugar adding ten drops of benedicts’ solution to our water and our glucose we then placed them in boiling water for 3 minutes and observed the color changes and differences. Next we tested the starch solution adding ten drops or iodine to the starch and to the distilled water after swirling the tubes we observed the color change and differences.
When we tested protein and fat we used the same procedure as the starch except we changed the reagents we used, we used Biuret for the protein test and we used Sudan red for the fat test.
Purple (top), Dark Blue (bottom)
Sudan Red reagent
In our macromolecule lab there were independent variables that we determined to be was the distilled water and the samples of macromolecules that we changed when we added the reagents. The dependants that did not change were the pipettes, the test tubes, the mortar and pedestal, the lab report sheet, and the test tube rack. The controls were the positive tests that we used as comparisons to determine if macromolecules were present in the food sample.
In my conclusive test my food which happened to be Cheddar and Sour cream chips did react to the reagents. The chips tested positive for starch, fat, and protein but mostly contained starch due to the potatoes that the chips are made of.