Lab Macromolecules

Pg 103 & 104 #’s 1-4

1. a. Monosaccharides are the subunits that make up carbohydrates.

b. Amino Acids are the subunits that make up proteins.

2. Each test is done initially by using water and a known sample because water is used as the negative control in the experiment to show what no reaction would look like.

3. a. The substance might taste sweet because it is converted to the aldose, glucose, and mannose by the base in the reagent.

b. Procedure A, to test whether or not there is a monosaccharide present in the solution.

4. For all experiments you must use a negative control and the known sample:

a. Starch: Use the iodine reagent. Use two test tubes, one for the negative control and one for the known sample. Put a few drops of iodide reagent into test tubes, shake/swirl the mixture and wait for the reaction. (Dark blue if presence of starch)

b. Lipid: Use a paper test. Place a drop of the negative control and the known sample on opposite sides of the paper. Rub it gently with your finger. Allow it to dry. Hold it up to the light. If lipids are present the paper will be translucent.

c. Sugars: Use Benedict’s reagent. Boil water in a beaker with boiling chips. Mix the known sample with the Benedict’s reagent in one test tube and the negative control with the Benedict’s reagent in the second test tube. Place in boiling water for 5 minutes. Cool and observe precipitate. (Red/orange coloring if presence of sugar)

d. Protein: Use biuret reagent. Use two test tubes, one for negative control and one for known sample. Mix with biuret reagent and wait for the reaction. (Light violet/lavender if presence of a protein)