BIOSC 0100 Lecture Notes - Lecture 14: Unsaturated Hydrocarbon, Lipid Bilayer, Membrane Lipids
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Document Summary
Amphipathic contains both a polar, hydrophilic region and a non-polar, hydrophobic region. Phospholipids have two regions called the head and tail(s) most common lipid membrane. The head region consists of glycerol (phosphate) and a charged group. The tail region is comprised of two nonpolar fatty acid or isoprene chains. Small or nonpolar molecules move across phospholipid bilayers quickly. Charged or large polar substances cross slowly, if at all. Factors that influence the behavior of the membrane include: # of double bonds, length of tails, # of cholesterol molecules in the membrane, temperature. The degree of phospholipid saturation and length of the hydrocarbon tails affect permeability. Short, unsaturated hydrocarbon tails have higher permeability than long, unsaturated hydrocarbon tails. Individual phospholipids can move laterally throughout a layer of the bilayer but rarely flip from one layer to another. The fluidity of a membrane depends on temperature, the structure of hydrocarbon tails, and the presence of cholesterol.