BSC 2010C Lecture Notes - Lecture 6: Lipid Bilayer, Passive Transport, Facilitated Diffusion
Document Summary
Boundary separating living cell from non-living surrounding environment. Fluid mosaic model- membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids. Cellular membranes: fluid mosaics of lipids and proteins. Integral (transmembrane if cross whole membrane)- penetrate the hydrophobic interior of the lipid bilayer. Peripheral- attached to one side or other, not embedded in the lipid bilayer at all, loosely bound to the surface of the membrane. Saturation level in fatty acid tails affects fluidity of plasma membranes. Steroid cholesterol- variable effects on animal cell membrane fluidity. Short, branched chains fewer than 15 sugar units. Carbohydrates bounds to lipids (glycolipids) or proteins (glycoproteins) cover outer surface of cells. A cell"s ability to distinguish one type of neighboring cell from another. Cells need to control exchange of material with environment. Passive transport- no energy needed move substance across membrane. Simple diffusion- molecules move from areas of high concentration to low concentration.
