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Biological Membrane & Fluid Mosaic Model

Biological membrane
  • Made up of phospholipid bilayer.

  • Makes the wall of cells and organelles.

  • Separates two fluid compartments, an inner compartment and an outer compartment.

Fluid Mosaic Model
  • Explains the fluidic nature of the biological membrane.

  • A biological membrane is basically a thin and strong sheet of fluid. This fluid is nothing but the two layers of phospholipid molecules.

  • Just like in any liquid, the phospholipid molecules are freely moving in this fluid.

  • Because the fluid is only two layers thin and it's very difficult for a phospholipid molecule to change the layer, the movement is only along the plane of the layer i.e. its 2-dimensional movement, rather than the 3-dimensional movement that we usually think of.

Bubble Analogy
  • You can compare a biological membrane with a bubble.

  • Just like how a bubble is a thin fluidic layer of water that separates two air compartments, a biological membrane is a thin fluidic layer of phospholipids that separates two water compartments.


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