Waiting
Login processing...

Trial ends in Request Full Access Tell Your Colleague About Jove

A subscription to JoVE is required to view this content.

Education
Macromolecules - Student Protocol
 

Macromolecules - Student Protocol

Procedure

  1. Identifying Macromolecules with Indicator Solutions
    • HYPOTHESES: In this activity, the experimental hypothesis might be that the addition of an indicator dye to each test solution will result in a color change if the test solution contains the macromolecule of interest. The null hypothesis might be that the addition of an indicator dye will not result in a color change in any of the test solutions.
    • Place 16 clean test tubes in a tube rack in four rows of four tubes and label each row A through D and each column 1 - 4.
    • Label each test tube with its corresponding position in the test tube rack.
    • After this, stir solution A thoroughly and use a pipette to add 4 mL of solution A to each tube in Row A.
    • Next, stir solution B until it is well mixed and use a new pipette to add 4 mL of solution B to each tube in Row B.
    • After stirring solution C thoroughly, add 4 mL of solution C to each tube in Row C.
    • Then add 4 mL of soybean-derived vegetable oil to each tube in Row D.
    • When all of the tubes have been filled with their respective test solutions, add 200 mL of water to a 400 mL beaker on a hotplate and set the hotplate to high.
    • To perform the Benedict's Test, add 2 mL of Benedict's reagent to test tubes A1, B1, C1, and D1 while the water is warming.
    • Observe the initial color of the tubes.
    • When the water begins to boil, transfer each test tube to the beaker and heat the tubes in the boiling water bath for 3 - 5 minutes.
    • Then, record the final color of each of the tubes in the appropriate cells of the table and turn off the hotplate. Click Here to download Table 1
    • To perform an Iodine-Potassium-Iodide Test, first observe the color of the solutions in the test tubes in column 2.
    • Then, add 1 mL of iodine potassium iodide reagent to tubes A2 to D2 and record the final color change in each of the tubes.
    • For the Sudan IV Test, observe and record the color of the solutions in the test tubes in column 3.
    • Then, add 2 - 3 drops of Sudan IV reagent to test tubes A3 through D3 and record the color change, if any, in each tube.
    • For the Biuret Test, observe the color of the solutions in the test tubes in column 4.
    • Then, add 1 mL of Biuret reagent to test tubes A4 through D4 and record the final color in each of the tubes.
  2. Results
    • Using the results from the indicator tests, each of the four original solutions can be identified as a sugar, starch, lipid, or protein. Refer to the Concepts video to help you determine which tubes contain which macromolecules.
    • First, look at the results from the Benedict's Test. Determine which of the test solutions contain sugar based on your results.
    • Next, create a bar graph with your five plant species listed on the x-axis and the surface area in cm indicated on the y-axis.
    • Next, look at the results from the Iodine-Potassium-Iodide Test. Determine which of the test solutions contain starch.
    • Now, review the results from the Sudan IV Test. Using these observations, determine if any of the test solutions contain lipids.
    • Finally, look at the results from the Biuret Test. Determine if any of the test solutions contain proteins.

Tags

JoVE Lab Lab: 18 Procedure

Get cutting-edge science videos from JoVE sent straight to your inbox every month.

Waiting X
Simple Hit Counter