BIOL 1090 Lecture Notes - Lecture 3: Lipid Bilayer, Biological Membrane, Membrane Protein
26 Feb 2018
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Document Summary
Phospholipid bilayer: ~6nm thick: biological membranes contain a hydrated lipid bilayer, amphipathic: having both hydrophobic (non polar) and hydrophilic (polar) regions. Membrane uidity is determined by: nature of lipids in membrane, unsaturated lipids increase uidity, increase in unsaturated lipids = lower temperature, saturated lipids decreases uidity, temperature, warming increases uidity = liquid crystal, cooling decreases uidity - crystalline gel. Membrane fluidity is crucial to cell function: balance between ordered (rigid) structure and disordered structure allows, mechanical support and exibility, dynamic interactions between membrane components (eg. proteins can come together reversibly, membrane assembly and modi cation. Cholesterol regulates membrane fluidity: alters packing and exibility of lipids, if added to a liquid crystal membrane, uidity will decrease, if added to crystalline gel membrane uidity ill increase. Biological membranes are asymmetrical: two lea ets have distinct lipid composition, in many plasma membranes, the outer lea et contains glycolipids and glycoproteins (have carbohydrate attached)
