Chapter 5: Membrane Structure and Function

Chapter 5: Membrane Structure and Function The Basics ● The structure of cell membranes results in selective permeability ● Cell membranes separate the internal environment of the cell from the external environment. ● Selective permeability is a direct consequence of membrane structure as described in the fluid mosaic model. Fluid Mosaic Model 1. Singer and Nicolson (1972) introduced this model 2. Embedded proteins are scattered throughout membrane in an irregular pattern Phospholipids: have two regions: Amphipathic- have both hydrophilic and hydrophobic regions Phospholipids spontaneously form a bilayer in an aqueous environment. 1. Heads: polar (hydrophilic) and directed outwards 2. Tails: nonpolar (hydrophobic) and directed to the interior