学习医学细胞生物学cell membrance.pptx

Cell Membrane;Shiping Ding Associated professor Cell biology Telephone： (office) E-mail： dingshiping@zju.edu.cn;Model of cell membrane; ;1.A brief history of studies on the structure of the plasmic membrane;? J.D.Robertson(1959): The TEM showing:the trilaminar appearance of PM; Unit membrane model; ? S.J.Singer and G.Nicolson(1972): fluid-mosaic model; ? K.Simons et al(1997): lipid rafts model; Functional rafts in Cell membranes. Nature 387:569-572; ;It’s like a fluid…It’s like a mosaic… It’s the Fluid Mosaic Model!;Cellular membranes have 4 components: phospholipid bilayer transmembrane proteins interior protein network cell surface markers;?membrane;Membrane Lipids;Membrane Lipids: The Fluid Part of the Model;Phospholipid structure consists of -glycerol – a 3-carbon polyalcohol acting as a backbone for the phospholipid -2 fatty acids attached to the glycerol -phosphate group attached to the glycerol;Figure. Four major phospholipids in mammalian plasma membranes. Note that different head groups are represented by different symbols in this figure and the next. All of the lipid molecules shown are derived from glycerol except for sphingomyelin, which is derived from serine.;phosphoglyceride;cardiolipin ;sphingolipid;glycolipids are membrane components composed of lipids that are covalently bonded to monosaccharides or polysaccharides. ;The amount of cholesterol may vary with the type of membrane. Plasma membranes have nearly one cholesterol per phospholipid molecule. Other membranes (like those around bacteria) have no cholesterol. They immobilize the first few hydrocarbon groups of the phospholipid molecules. This makes the lipid bilayer less deformable and decreases its permeability to small water-soluble molecules. Without cholesterol (such as in a bacterium) a cell would need a cell wall. Cholesterol prevents crystallization of hydrocarbons and phase shifts in the membrane.;;micelles; bi