BSC 1010C Lecture Notes - Lecture 7: Phagocytosis, Exocytosis, Active Transport
27 Sep 2016
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Selective permeability: some materials can cross others cannot (cell membrane) *phospholipid bilayer membrane is uid : they freely move laterally within their half of bilayer. *lateral movement (-10^7 times per second) flip flop (-once per month) Unsaturated fatty acids have kinky chains that don"t pack as closely together, increasing membrane uidity, *degree of fatty acid saturation also affects permeability of lipid bilayer* Saturated (pack more tightly together) : lower permeability. Charge and size determine a solute"s ability to cross phospholipid bilayer. Hydrophobic molecules : o2, co2,n2 ( pass easily ) Small, uncharged polar molecules : h2o ( pass ) Large, uncharged polar molecules: glucose, sucrose ( only slightly ) Are embedded within, upon and across the phospholipid bilayer. Membrane transport proteins conduct polar and charged ions across (very speci c about which solutes they transport. No, they can not get passed the hydrophobic anterior because they are hydrophilic ions.
