BIOL 1201 Chapter : Biol Chapter 7
Document Summary
>>>>>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 lipid 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. 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. How do the proteins stay attached? proteins: 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: mosaic aspect of membranes means that there are proteins interspersed within the lipid bilayer. A membrane is a fluid mosaic of lipids, proteins, and carbohydrates. Proteins as the mosaic of the cell membrane.
