Maintaining optimal cell membrane fluidity is important for several reasons including:

• Proper functioning of the cell
• To enable membrane lipids and proteins to diffuse from the site of synthesis to areas of the cell where they are needed
• To facilitate the interaction between membrane proteins, which is crucial for cell signaling and other function
• To enable membranes to fuse with one another and mix molecules under appropriate conditions
• To ensure the even distribution of membrane molecules between daughter cells after cell division

All living cells maintain cell membrane fluidity within a certain range.

Cell membrane fluidity may be affected by length of the fatty acid tail, degree of saturation of fatty acid tails, cholesterol content of the bilayer and temperature.