EXCI 257 Study Guide - Midterm Guide: Lipid Bilayer, Membrane Transport Protein, Peripheral Nervous System
11 Apr 2018
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*network of information transmission = facebook: thin, elastic, 7-10 nanometers thick, composed almost entirely of lipids and proteins (lipid barrier, proteins, carbohydrates) Lipid barrier: lipid bilayer of the membrane, composed of 2 layers of phospholipid molecules: *phosphate portion (head) = soluble in water (hydrophilic) *fatty acid portion (tail) = only soluble in fats (hydrophobic: form a barrier: *impermeable to water and water-soluble substances (ions, glucose, urea, etc. ) *permeable to lipid-soluble substances (oxygen, nitrogen, carbon dioxide, alcohol) Cell membrane proteins: membrane proteins transport water-soluble substances across the cell membrane. Attached to only one surface of the membrane (often attached to integral proteins) Act as enzymes, controller of transport through channels. Two basic processes of transport: diffusion = passive transport (no energy, simple diffusion (lipid bilayer or channel proteins) Interstices of lipid bilayer for lipid-soluble molecules (oxygen, nitrogen, carbon dioxide, alcohol. Channel proteins: water and lipid-insoluble molecules (ions, urea, etc. )
