======Egg Yolk Cell Membrane======


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**Alternative titles:** Cell Membranes from Eggs
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====Summary====                   
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====Procedure====  
  - Begin by explaining to students that all living things are made of cells, and each cell is surrounded by a membrane.  
  - Pour 100 mL of water into a flask.  
  - Add 25 mL of oil into the flask.  
  - Shake the flask, then let it settle so the oil and water separate. Point out that they do not mix, similar to how a membrane forms a barrier.  
  - Crack an egg into a small dish.  
  - Use an eye dropper to collect some of the yolk.  
  - Drop small amounts of the yolk into the oil-water mixture.  
  - Observe how the yolk forms structures that resemble cell-like boundaries, illustrating how cell membranes create separation and stability.  




====Links==== 
egg yolk as emulsifier - Ssie Altalef: 
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📄 CELL MEMBRANES FROM EGGS (Page 16) - Sarah Groth: [[https://www.unco.edu/nhs/science/pdf/demos/2009_CSC_demos.pdf]]\\



====Variations====
  * Use food coloring in the water to make the separation more visible.  




====Safety Precautions====
  * Wash hands thoroughly after handling raw egg.  
  * Clean surfaces and materials that come into contact with raw egg to prevent bacterial contamination (e.g., salmonella).  
  * Dispose of egg mixture properly—do not leave it sitting out in a classroom.  




====Questions to Consider====
  * Why is it important for cells to have membranes?  
  * How does the cell membrane protect the cell from its environment?  
  * Why do oil and water not mix, and how does this relate to membrane structure?  
  * What might happen if a cell did not have a membrane?  
  * How does this demonstration model the process of cells forming from preexisting cells?