CELL MEMBRANE: STRUCTURE AND FUNCTION

• Structure of the Cell Membrane

  The cell membrane is a fluid of mosaic lipids and proteins. Being fluid indicates that the membrane "flows like water", and mosaic means that it is heterogenous in its appearance.
• Phospholipid


  Contains a phosphate group in its head

  • is an amphipathic molecule meaning that it has a hydrophilic head that gets attracted by water and a hydrophobic tail which gets repelled.
• Saturation


  The higher the saturation, the less space there is for phospholipids to move, thus making the cell membrane less fluid.
• Unsaturated Phospholipids


  Introduce kinks, which free up some space in the membrane making the cell membrane more fluid.
• Presence of Cholesterol

  Effect of cholesterol on fluidity depends on temperature.

  • At low temperatures, cholesterol prevents phospholipids from packing closely , thus increasing fluidity.
  • At high temperatures, cholesterol prevents them from scattering away, thus decreasing fluidity.