Membrane Fluidity Transition Temperature

The lipid bilayer, which consists of two layers of lipids (fatty acids containing a polar head group and non-polar hydrophobic tails) is a fluid structure because of the internal and outer components that allow for substances to enter and leave cells.

The transition temperature is the temperature at which a bilayer transitions from a gel-like solid to a liquid crystal.

  • If the membrane is below transition temperature = gel-like structure
  • If the membrane is above the transition temperature = liquid crystal

Factors That Affect The Transition Temperature:

  • Length of fatty acid tails
    • Longer fatty acid tailers = higher transition temperature
  • Degree of saturation
    • More saturation = higher transition temperature
  • Presence of cholesterol
    • In animal cells, the presence of cholesterol¬†makes structures less fluid. However, cholesterol¬†is interesting in that it broadens the transition temperature range because it is rigid (making it less fluid), but the tails of cholesterol¬†are more disordered which makes it a plasticizer.
      • A plasticizer broadens the gel transition temperature

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