Thursday, January 20, 2011

Experiment - Cellular Membrane and Osmosis

Lil Muallim # 1 "Cellular membrane and  Simple Osmosis"

Studying the basic structure and characteristics of a cell and it's membrane.

What I know :

The egg is actually the largest cell in the world. The calcium carbonate makes up its outer shell. It is made up of  calcium carbonate (CaCO3) crystals. This is just an outer coating protecting the actual cell membrane. The cell membrane encloses the eggs yolk (nucleus) and white (cytoplasm).

Simple anatomy of an egg can be learnt here

Materials Needed:
An egg
Clean glass wide necked bottle

vinegar coffee maker
Regular white vinegar


Paper Towel


  1. Place an egg in a medium sized jar.
  2. Fill the jar with vinegar until it covers the egg
  3. Leave it for 3-5 days
  4. On the 4th or 5th take out the egg and wash it gently with water removing the powdered calcium coating
  5. Observe the egg in the dark with a torch
  6. Place the egg on absorbent paper towel and try touching it gently
  7. Leave it like this for about a day
  8. Place the dehydrated egg in a bowl of water overnight


#1 Bubbles started forming inside the jar as the acetic acid in the vinegar starts to react with the calcium carbonate crystals in the egg shell.

# 2  After a day in the vinegar the egg shell started softening.

# 3 The appearance of  the egg shell changed as its chemical composition changed. The solid Calcium Carbonate crystals broke apart in the acetic acid releasing carbon dioxide gas.

# 4 The calcium turned into powder and was easily removable when rubbed gently

# 5 The egg looked slightly larger because it had absorbed some of the vinegar, showing that the cellular membrane is semi permeable (can pass through some air and moisture) and osmosis (simply the transfer of molecules from one medium into the other).

# 6 The cellular membrane is translucent and the yolk can be seen bobbing in egg white (albumen) through it, because of it bright color 

A raw egg with it's egg shell dissolved

(you can also try looking at it in dark with a torch I couldn't get a clear picture with my camera but this website shows how we saw it) 

# 7 The egg was bouncy showing the elasticity of the cellular membrane as it is partly made up of keratin (a fibrous protein)

# 8 When left to dry out on an absorbent paper towel the egg shrivels up as it paper towel absorbed the moisture from egg. This again shows the semi permeable characteristic of the cellular membrane 

# 9 When the dehydrated egg is placed in water, it restores its shape as it regains moisture through osmosis.

# 10 It is still bouncy as before. Subhanallah!


The cellular membrane encloses and protects the inner parts of the cell, It is stretchy because of keratin a string fibrous protein. It is also translucent. Osmosis can easily take place as the cellular membrane is semi permeable.


The egg does bounce watch it in this video I found 

NOTE: We used the same egg frim Lil Muallim # 2's experiment and we did the dehydration and hydration part twice on the same egg and it worked perfectly.\After the second hydration it was still bouncing as the first time.


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