demonstrations:ping_pong_ball_lipid_bilayer

Ping Pong Ball Lipid Bilayer

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★☆☆ Minimal safety procedures required

Categories: Mixtures and Separation, Cells and Microscopes

Alternative titles: Fluid Mosaic Model

Summary

This model demonstrates the fluid mosaic structure of the cell membrane using ping-pong balls, drinking straws, water, oil, and salt water. The arrangement represents a phospholipid bilayer with hydrophilic heads and hydrophobic tails, showing how the membrane behaves in an aqueous environment.

Procedure

  1. See the links section below for full instructions.

Variations

  • Add beads or small objects to represent proteins embedded in the membrane.
  • Use food coloring in the water phase to emphasize separation.
  • Show facilitated diffusion by using magnets to move objects across the “membrane.”
  • Compare the model to diagrams of real cell membranes for discussion.

Safety Precautions

  • Use caution when drilling holes in ping-pong balls.
  • Handle hot glue carefully to avoid burns.
  • Ensure oil and water are disposed of properly, not poured down the sink in large quantities.

Questions to Consider

  • How does this model represent the phospholipid bilayer? (Hydrophilic heads interact with water, while hydrophobic tails avoid it and remain in the oil layer.)
  • Why are the tails considered hydrophobic and the heads hydrophilic? (Due to their chemical polarity.)
  • How does this model demonstrate the “fluid” aspect of the membrane? (The components are not rigid but can move within the layer.)
  • How could proteins or channels be added to improve the accuracy of the model?
  • What are the limitations of this model compared to a real cell membrane?