An Egg as a Cell

Posted by Allyson Greene at 4/7/2010 3:00:00 PM

To help increase the understanding of cells, 5th graders conducted an experiment which demonstrated the function of the cell membrane, along with learning how cells were discovered and the differing parts of a cell. This experiment also taught students about diffusion and osmosis. We were fascinated to learn how our own cells have the power to take in what the may need, as well as to get rid of what they should not have through this process of osmosis!

This was a 2 day experiment in which students first removed the shell of an egg by soaking it in vinegar overnight. When they observed the egg the next day, they noticed it did not have a shell and that the shell had dissolved into the vinegar. They also observed that the egg was swollen, or through osmosis, the yolk expanded as it moved from a higher area of concentration to a lower area of concentration. (This is diffusion!) The mass increased on all of the eggs and to show how the egg is like a cell, we had the students soak their eggs for 15 minutes in colored water. Then, we had them pop their egg (gross, but lots of fun!)! What was left was the cell membrane of the egg and we observed that the membrane was the color of the food coloring from the water.

Students hypothesized that if we would have left the egg in the colored water longer, say overnight, that osmosis would have caused the yolk and cytoplasm to become the color of the water!

Later on next week, 5th graders will analyze onion and cheek cells to compare an animal cell to a plant cell.

measuring

recording

No shell!!!

Osmosis

popping the egg

will it pop

cell membrane