Introduction: The purpose of each experiment is to test which macromolecules are present in each of the different pieces of food, with the foods being apple, potato and hot dog.
These experiments, in total, will test for the presence of three of the major four macromolecules, carbohydrates, lipids and proteins. The following are my hypotheses concerning each of the experiments:
Carbohydrates - The apple will react, the hot dog will not react, the potato will not react.
Starch - The apple will react, the hot dog will not react, the potato will react.
Lipids - The oil will leave a trace of something while the water spot will dry without anything unusual happening.
Proteins - The apple will not react, the hot dog will react, the potato will
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- Add a dropperful of biuret reagent to each test tube and swirl gently to mix. Allow to sit for two minutes. - Record the color of the tubes after the two minutes have passed. Compare results.
Results: The following are the results of each experiment individually:
Carbohydrates -
Test Tube
Results
Control (Positive)
The liquid at the top of the test tube turned orange while still in the boiling water, with the color slowly running down as time went on. After being left to cool, the color had changed to a dark orange/almost brown color.
Control (Negative)
The solution remains its original color (blue)
Apple
A red-orange color developed while the test tube was in the boiling water. After the mixture had cooled, the color was red.
Hot Dog
The mixture began to turn yellow while the test tube was in the boiling water. By the end, after the tube had cooled, the color was yellow-green.
Potato
The mixture began to turn greenish at the bottom of the tube. At the end of the experiment, the mixture and become completely
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A limitation of this experiment is that Benedict’s reagent does not react with all small sugars, such as sucrose.
Starch - During this experiment none of the foods reacted with the iodine reagent, which would lead one to believe that starch is not present in any of these foods. However, it is well known that starch is a storage polysaccharide in plants, so clearly something went wrong. It is clear that there are some limitations to this experiment. One, possibly, could be that the foods need to be properly mashed or liquified for the reagent to be properly exposed to the starch.
Lipids - This experiment was not done with the foods, as properly liquefying and smearing the foods onto the paper towel would have been disadvantageous. This is a limitation to the experiment. Another limitation is that cross contamination is very likely to happen, as an unclean work surface could ruin the entire