The fluidity of cell membranes is greatly influenced by temperature. Cell membranes are primarily composed of phospholipids, which form a bilayer structure. The fluidity of the membrane depends on the movement and interactions of these phospholipids.As temperature increases, the kinetic energy of the phospholipids also increases, causing them to move more rapidly and freely. This increased movement results in a more fluid and flexible cell membrane. In contrast, as temperature decreases, the kinetic energy of the phospholipids decreases, leading to reduced movement and a more rigid, less fluid membrane.At very low temperatures, the cell membrane can become too rigid, which can impair the function of membrane proteins and the transport of molecules across the membrane. On the other hand, at very high temperatures, the membrane can become too fluid, which can compromise the integrity of the cell and lead to cell damage or death.To maintain optimal fluidity, cells can adjust the composition of their membranes by altering the ratio of saturated and unsaturated fatty acids in the phospholipids. Unsaturated fatty acids have double bonds that introduce kinks in their hydrocarbon chains, preventing them from packing tightly together and increasing membrane fluidity. Saturated fatty acids, on the other hand, have no double bonds and can pack more closely together, leading to a more rigid membrane. By adjusting the ratio of these fatty acids, cells can maintain the appropriate membrane fluidity across a range of temperatures.