Question

What is transition temperature in regard to structure of cell membrane?

Answer 1

Transition temperature is the temperature at which there is a transition from ordered structure of fatty acid tails to unordered.
Chain length of fatty acids α Tm
Degree of unsaturation 1/α Tm
Cis double bonds contributes to fluidity.
Role of cholesterol:
Rigid steroid ring system interferes with the lateral movement of fatty acid chains.
At lower temperatures: ↑ fluidity
At higher temperatures: ↓fluidity