BSC-2010 Chapter Notes - Chapter 7: Cytoskeleton, Natural Selection, Lipid Bilayer
28 Feb 2017
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Document Summary
Plasma membrane separates the living cell from surroundings. Controls traffic into and out of cell. Selective permeability - allows some substances to cross it more easily than others. Cellular membranes are fluid mosaics of lipids and proteins. Amphipathic - has both a hydrophilic region and a hydrophobic region. A phospholipid bilayer can exist as stable boundary between 2 aqueous compartments (hydrophobic tails away from water and hydrophilic heads to water) Fluid mosaic model - membrane is mosaic of protein molecules bobbing in a fluid bilayer of phospholipids. Proteins are not random - they are grouped together by specialty carrying out common functions. Hydrophobic interactions are weaker than covalent bonds. Lateral movement - most lipids and some proteins. Rapid - adjacent phospholipids switch positions 107 times per second. Proteins are much larger than lipids - move slower. Membrane remains fluid as temperature decreases until the phospholipids settle. Temperature dependent on type of lipids being solidified.
