What Organic Molecule is this? Identifying Organic Molecules Using Chemical Tests
By: Jennifer Park
Partner: Meredith Commins
Georgia Perimeter College
Biology 2107 Lab
Professor: Dr. Thomas Oh
Introduction In this experiment, the three out of four major organic molecules were studied: carbohydrates, lipids, and proteins. The purpose of the experiment was to familiarize the methods for identifying and distinguishing different organic molecules using several tests and chemicals. Each organic molecule has a specific test to chemically distinguish them from one another.
To test for carbohydrates, the Benedict's Test is used to reveal the presence of monosaccharides, a simple sugar (glucose and fructose)…show more content… 7 different test tubes were used and each labeled with one of the following: Water (negative control), Monosaccharide (glucose positive control), Disaccharides (maltose), Sucrose, Lactose, Polysaccharide (starch) and Unknown A. Each test tube received a total of 4 ml of solution; to increase productivity, each tube was marked at the 2 ml line and 4 ml line using a 10ml graduated cylinder. Each tube had a label and 2 lines to indicate what solution was being tested and how much to add. A hot plate was prepared with tap water filled half way in a beaker and preheated to boiling. Then, 2 ml of the labeled solutions were added to the tubes; each tube was filled to the first line from the bottom (which marks 2 ml) with the correctly labeled solution. When the water was boiling, the tubes were then filled to the second line (which marks 4 ml) with the Benedict's solution (approximately 2 ml). The tubes were placed in the hot water beaker all at the same time. As soon as the Monosaccharide (glucose positive control) turned red, all the tubes were taken out carefully and any color changes were recorded.
The polysaccharides: starches were tested next using the Lugol's Test. This was done almost the same way as testing for carbohydrates. 7 new tubes are used and labeled the same except this time polysaccharide were the positive control, iodine was used instead of the Benedict's solution and no heat was…show more content… Initially the time increment were 5 mins, however, after 10 mins the results did not show any change and all the solutions were the same color. Realizing that the rate of reaction is less was less than 5 mins the time increment was changed to 1 min. After this change was made the results showed that the solution this the higher ratio of starch was the darkest then the 50/50 ratio and finally the solution with more amylase was the lightest. This showed that starch will be broken down into maltose when amylase is added indicating the importance why the amylase enzymes is helping us in our body system (De Souza,