Testing Macromolecules Lab Name:
Biology 6.0
Pre-lab:
1.
Write out the objective of the lab.
2.
Answer all of the questions in the prelab.
3.
Write the procedure summary .
4.
Include ALL data tables for the lab.
Date: Period:
Pre-Lab Questions:
1.
What elements are present in all macromolecules?
2.
What elements are present in proteins not found in carbohydrates or lipids?
3.
Biurets solution reacts with the peptide bonds in the polypeptide chains. A purple colored complex is formed. What macromolecule has peptide bonds?
4.
What are the monomers for lipids?
In the previous lab, we tested for carbohydrates using Benedict’s and Iodine solutions. For this lab, we will be using Biuret Solution to test for proteins and Alcohol to test for lipids . You will be given unknown mixtures to determine what macromolecules are contained in your samples.
Procedure:
Materials : Biuret solution, ethanol, iodine, Benedict’s solution, test tubes, test tube rack, test tube clamp, beaker
PART I: Indicators with known macromolecules
1.
Label all of your test tubes. See procedure for labeling.
2.
Fill a test tube with 3 mL of distilled water. This will be your height reference for all solutions in the lab.
3.
Fill another test tube with distilled water to about the same height as the first test tube.
4.
Fill 1 test tube with the gelatin – same height as the dI water.
5.
Fill another test tube with albumin (egg white) – same height as the dI water.
6.
Fill a third test tube with corn oil – same height as the dI water.
7.
Add 5 drops of Biurets to the distilled water and to each test tube containing a sample. Record your observations. Did a color change occur?
8.
Clean and rinse the three test tubes. Do not discard the dI water.
9.
Fill the three test tubes with the samples following steps 4-6.
10.
Add ethanol to the distilled water and to the other samples. Heat alcohol-sample mixture in a hot water bath until sample is transparent . If it does not turn transparent, add more alcohol.
11.
Pour sample containing the alcohol into a test tube filled ¼ of the way with distilled water. Record your observations.
Part II: Identifying the macromolecules in unknown solutions.
You will be testing the unknown solutions for carbohydrates, lipids and proteins using all of the indicators - from the carbohydrate lab as well as this lab. Create an easy to read data table which will organize your observations, results, and interpretations in an organized fashion.
Post Lab:
Answer the following questions:

Biurets test tests for what type of macromolecule?

The alcohol tests for what type of macromolecule?

What is your unknown number? What macromolecules were in your unknown?