ENG BE 209 Chapter Notes - Chapter 11: Micelle, Membrane Transport, Hydrophile
30 Jul 2018
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Document Summary
Plasma membrane: a fatty film so thin and transparent that it cannot be seen directly in the light microscope. Facilitates the flow of nutrients and waste products. Most abundant lipids in cell membranes are the phospholipids. Hydrophilic heads face the water from both surfaces of a lipid bilayer. The hydrophobic tails are all shielded from the water. Amphipathic: molecules with both hydrophilic and hydrophobic properties. If there is a tear, molecules of the bilayer will spontaneously rearrange to eliminate the free edge. The lipid bilayer is a two-dimensional fluid. Phospholipid molecules very rarely tumble from one half of the bilayer to the other. The fluidity of a lipid bilayer depends on its composition. Saturated: fatty acid tail with no double bonds. Membrane fluidity enables membrane proteins to diffuse rapidly in the plane of the bilayer and to interact with one another in cell signaling.
