BIOL 1201 Chapter : Biol 1201 Outline 7
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>>>>>membrane structural models have evolved as new data is acquired. Biochemical detective work: 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. --amphipathic is a condition where a single molecule has both hydrophilic and hydrophobic regions. *phosphate head (charged)-hydrophillic: cell membranes are phospholipid bilayers (see fig 7. 2) Evidence: the phospholipid content of red blood cells is just enough to cover the cell with two layers. The red blood cell has no internal membranes. Hydrophilic zones = polar head groups + globular proteins. About 8 mm thick: biological membranes contain proteins. Evidence: membranes isolated from red blood cells contain proteins in addition to lipids: biological membranes are coated with proteins that generally absorb water. Evidence: biological membranes absorb more water on their surface than artificial phospholipid membranes.