BIOL 1081 Lecture Notes - Lecture 11: Cell Membrane, Unsaturated Hydrocarbon, Alkane
Document Summary
A membrane remains fluid as temperature decreases until the phospholipids settle into a closely packed arrangement and the membrane solidifies. The temperature at which a membrane solidifies depends on the types of lipids it is made of. The membrane remains fluid to a lower temperature if it is rich in phospholipids with unsaturated hydrocarbon tails. Because of kinks in the tails where double bonds are located, unsaturated hydrocarbon tails cannot pack together as closely as saturated hydrocarbon tails, making the membrane more fluid. At relatively high temperatures-37 degrees c- cholesterol makes the membrane less fluid by restraining phospholipid movement. However, because cholesterol hinders the close packing of phospholipids, it lowers the temperature required for the membrane to solidify cholesterol= fluidity buffer for the membrane, resisting changes in membrane fluidity that can be caused by changes in temperature. The fluidity of a membrane affects both its permeability and the ability of membrane proteins to move to where their function is needed.
