ENGL 301 Chapter : Doc1
15 Mar 2019
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Evidence: lipids and lipid soluble material enter quicker than substances which. >>>>>membrane structural models have evolved as new data is acquired. Biochemical detective work: membranes are made of lipid are insoluble in liquid, phospholipids are amphipathic molecules that can form membranes. --amphipathic regions: cell membranes are phospholipid bilayers (see fig 7. 2) cell with two layers. Evidence: biological membranes absorb more water on the surface than artificial. Hydrophilic zones = polar head groups + globular proteins. Singer and nicolson: fluid-mosaic model (see fig 7. 3) Confirmed by freeze-fracture and freeze-etch micrographs (see fig 7. 4) Hydrophilic zones = polar head groups + hydrophilic portion of proteins. Hydrophobic zone = 2 x hydrophobic tails + hydrophobic portion of proteins lateral two-demensional movement of lipids and some of the proteins in the plane of the membrane. However transverse (flip flop) across the membrane is rare. A membrane is a fluid mosaic of lipids, proteins, and carbohydrates. Proteins as the mosaic of the cell membrane.
