BISC 101 Lecture Notes - Lecture 5: Exocytosis, Endocytosis, Electrochemical Gradient
19 Jun 2015
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Document Summary
Bisc 101 lecture 5 cell membrane structure and function. Cell membrane structure & function: cellular membranes are fluid mosaics of lipids and proteins, the plasma membrane or cell membrane separates life from nonlife. Large charged polar molecules cannot pass through the nonpolar hydrophobic tails of a lipid bilayer. Fluidity of membranes: phospholipids in the plasma membrane can move within the bilayer, most of the lipids and some proteins, drift laterally, barely does a molecule flip flop transversely across the membrane. Bond saturation and hydrocarbon chain length change membrane permeability: hydrophobic tails are packed in the center of a lipid bilayer. Lipid bilayers become more permeable and fluid when they consist of short, unsaturated hydrocarbon tails: the interior is held together less tightly, allowing more materials to pass. Cholesterol change membrane permeability: steroid rings in cholesterol are bulky, high cholesterol concentration in cell membranes lead to decrease in membrane fluidity. 5: attachment to the cytoskeleton and extracellular matrix.
