BIOL 1201 Chapter : Biol 1201 Outline7
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>>>>>membrane structural models have evolved as new data is acquired. Earliest models were deduced from indirect evidence: membranes are made of lipid, evidence: lipids and lipids soluble material enter quicker than substances which are insoluble in lipid, phospholipids are amphipathic molecules that can form membranes. Hydrophilic zones = polar head groups + globular proteins. Hydrophilic zones = polar head groups + hydrophilic portion of proteins. Hydrophobic zone = 2 x hydrophobic tails + hydrophobic portion of. Singer and nicolson: fluid-mosaic model (see fig 7. 3) Confirmed by freeze-fracture and freeze-etch micrographs (see fig 7. 4) --fluid- means lateral two-dimensional movement of the lipids and some of the proteins in the plane of the membrane. However, transverse (flip-flop) across the membrane is rare. --mosaic- aspect of membranes that means there are proteins interspersed within the lipid bilayer. Proteins as the mosaic of the cell membrane. A mosaic of different proteins are embedded in the lipid bilayer.
