BIOC312 Lecture Notes - Lecture 8: Lipid Bilayer, Fluid Mosaic Model, Endoplasmic Reticulum
28 Jul 2016
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Document Summary
Define external boundaries of cells and cellular components- provide regulated barrier to transport of selected solutes. Biological membrane consists of proteins embedded in or associated with lipid bilayer. 25-50% lipid and 50-75% proteins (by mass) Variable, depending on type of membrane and specieslipids include phospholipids, sphingolipids, cholesterol- variable depending on membrane type lomoarcpsd. Some membranes contain protein pumps for ions or small molecules. Some membranes generate proton pumps for atp production. Membrane receptors respond to extracellular signals and communicate them to cell interior. 30% of genes in the human genome encode for membrane proteins. Lipids provide permeability barrier, proteins mediate nearly all other membrane processes. Noncovalent interactions among amphipathic lipid molecules make them flexible and self healing. Two leaflets (or monlayers) of a bilayer membrane tend to differ in their lipid composition- sphingolipids in outer leaflet, glycerophospholipids in cytosilic leaflet. Fluid mosaic model- proteins fluid in a lipid- bilayer sea.
