Egg Macromolecules Lab

The egg membrane tested positive for having polysaccharides, lipids, and proteins. When the test tube that contained egg membrane was tested for proteins, and sodium hydroxide with copper sulfate was added, it turned from blue to purple, and we knew that proteins were present. It is logical that proteins would be found in the egg membrane because transfer proteins are used to transport substances back and forth through the cell.
The egg white tested positive for all four macromolecules: monosaccharides, polysaccharides, lipids, and proteins. We added benedicts solution, iodine, Sudan III, and sodium hydroxide mixed with copper sulfate, to see if monosaccharides, polysaccharides, lipids, or proteins respectively, were present. The test tube with benedicts turned from blue to green to orange, the test tube with iodine turned from brown to black, the test tube with Sudan III turned from red to orange. Monosaccharides, polysaccharides, and lipids are needed in the egg white for proper growth and development of the chick (if the egg was fertilized).
The egg yolk tested positive for proteins and lipids. The test tube which had Sudan III added turned from brown to black, which showed that lipids were present. The egg yolk is the actual cell, and lipids were sure to be found in the membrane.

While our hypothesis was supported by our data, there could have been errors due to how much chemical was added into each test tube, and how each part of the egg was separated and put into its own test tube. We might have added too much or too little of each chemical to each sample due to errors in how big each drop was. If one test tube had more chemical than another, it would affect if the egg tested positive for that molecule, or what color it turned. It was also difficult to isolate the egg membrane, and I believe there was still egg white mixed into the test tube when we tested the membrane. Due to these errors, in future experiments I would recommend that we use an instrument to cut the membrane and measure how much chemical we add before we add it.

This lab was done to demonstrate our understanding of where macromolecules are found in the cell. From this lab, I learned firsthand how phospholipids are found in the membrane, as well as transport proteins and carbohydrate chains (polysaccharides). Based on my experience in this lab, I better understand where the different macromolecules are found.