BIOMG 1350 Chapter Notes - Chapter 11: Beta Barrel, Glycocalyx, Actin
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18 Sep 2016
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Plasma membrane: protein-studded, fatty film, separates and protects chemical components of cell from outside, two-ply sheet of lipid molecules (5 nm thick) and proteins. Highly selective channels and transporters for transport of small molecules and ions in and out. Sensors, receptors response to environment: internal membranes organelles (prokaryotes have single plasma membrane) Membrane lipids form bilayers in water: phospholipids. Phosphatidylcholine (small molecule choline attached to phosphate group as hydrophilic head) Most common phospholipid in cell membranes: amphipathic. Properties play crucial part in driving lipid molecules to assemble: self-sealing. Hydrophilic heads face water on both surfaces of bilayer. Hydrophobic tails are shielded from water (lie next to each other in interior) If tear, rearrangement or fold in on itself forming vesicles. The fluidity of a lipid bilayer depends on its composition: length and number of double bonds in hydrocarbon tails how they pack, short chain length reduces tendency of hydrocarbon tails to interact.