Egg Macromolecules Lab Conclusion

In this lab, we asked which macromolecules, monosaccharides, polysaccharides, proteins, and lipids, if any, are found in the yolk, white, and membrane of an egg. We found that the egg yolk contained monosaccharides, the egg white contained monosaccharides, polysaccharides, proteins, and lipids, and the egg membrane contained monosaccharides, polysaccharides, and lipids. We tested for monosaccharides using benedicts solution, a solution that turns from blue to either green or orange in the presence of monosaccharides. When tested with the benedicts solution, the egg membrane turned dark blue, the egg yolk turned green-blue, and the egg white turned a different shade of blue, indicating monosaccharides in all 3. When testing for polysaccharides, iodine, which turns from brown to black in the presence of polysaccharides, was used to test for them. The iodine caused the egg membrane to turn dark brown, and the egg white to turn orange/light brown, which indicated polysaccharides in the egg membrane, and very few polysaccharides in the egg white. A mixture of Sodium Hydroxide (NaOH) and Copper Sulfate (CuSO₄) was used to test for proteins because when mixed with proteins, it turns from blue to purple. When mixed with all parts of the egg, only the egg white changed to a darker blue, which indicated proteins. Finally, we tested for lipids. For lipids, we used the chemical Sudan III, which changes from red to orange in the presence of lipids. Using that, the egg membrane and egg white turned orange, indicating lipids in both. The reason we found monosaccharides, polysaccharides, and lipids in the egg white was because they are used for energy by the developing organism. Proteins were found there because the organism can break them down and make its own proteins. The egg membrane had polysaccharides because they are used to communicate with other cells, and lipids were found because the membrane is made of phospholipids. Monosaccharides should not have been found, and were probably due to an experimental error. The yolk contained monosaccharides for energy.

Our data was unexpected due to various errors we made. When data from other identical experiments run in the class was compared, many people found macromolecules in parts of the egg that other groups didn't. In the egg membrane, we should have found proteins in addition to all of the other molecules we found because proteins are used during active transport in the egg membrane. In the egg yolk, we should have found polysaccharides for energy, lipids for the membrane around the yolk, and proteins for the developing organism. These errors were most likely caused by the color the egg yolk affecting the color of the chemical that was supposed to reveal the macromolecules. To fix this, less of the egg and more of the chemical should be used to test so the chemical reaction is more visible. Another error was in the lipid test. It was difficult to distinguish between the red that the chemical started as, and the orange it turned into because they are similar colors. To fix this, we could, again, use more of the chemical and less of the egg parts.

This lab was done to demonstrate where macromolecules are found in cells, and why there are there. From this lab I learned the purpose of different macromolecules, which helps me understand how cells carry out actions such as developing proteins and converting energy. Based on my experience from this lab, I can more accurately judge the effect of obvious errors in experiments, and have a better understanding on how cells work.