BIOL 3113 Lecture Notes - Lecture 13: Lipid Bilayer, Membrane Structure, Cellular Compartment
Document Summary
Plasma membrane - the skin of the cell. Varies slightly between different organelles and plasma membrane. Regardless of location all cell membranes are composed of lipids and proteins and have common general structure. *lipids - ~50% of mass of most membranes. Lipids - arranged in two closely apposed sheets - lipid bilayer. Lipid bilayer - provides basic structure and serves as a permeability barrier. *lipids - 50% of mass of most membranes: *phospholipids - most abundant membrane lipids, phosphatidylcholine - most common phospholipids, phosphatidylserine - negatively charged, phosphatidylethanolamine, sphingomyelin, *cholesterol, *glycolipids. Energetically most favorable arrangement of lipid molecules in aqueous environment. Self-sealing property of bilayer - driven by hydrophobic nature of tails - spontaneous elimination of free edges formation of self-sealing containers defining closed compartments. Mobile lipids: rotate, diffuse laterally, flex fatty acid tails, flip-flop from one side to the other (rare event) Flexibility - ability of the membrane to bend and withstand other deformations.
