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, phospholipids are amphipathic molecules that can form membranes. --amphipathic: cell membranes are phospholipid bilayers (see fig 7. 2, biological membranes contain proteins, biological membranes are coated with proteins that generally absorb water. Singer and nicolson: fluid-mosaic model (see fig 7. 3) 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 proteins. Confirmed by freeze-fracture and freeze-etch micrographs (see fig 7. 4) A membrane is a fluid mosaic of lipids, proteins, and carbohydrates. A mosaic of different proteins are embedded in the lipid bilayer. These proteins have two types of spacial arrangements. Some functions of integral membrane proteins (see fig 7. 10) Membranes have a bifacial orientation (i. e. sidedness) (see fig 7. 12) Solubility characteristics of the substance crossing the membrane.
