BIOS1167 Lecture Notes - Lecture 6: Lipid Bilayer, Semipermeable Membrane, Amphiphile
4 Sep 2018
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Document Summary
Selective transport from nutrients and waste products (semi-permeable) Consists of phospholipid bilayer (peripheral (some embedded and some on surface) and integral proteins, cholesterol) Peripheral proteins proteins which sit on the surface. Protein 55%, phospholipid 25%, cholesterol 13%, lipids 4%, carbohydrate -3% Has proteins, glycoproteins, glycolipids which sit on the surface. Remains in a state of quasi-fluid almost a liquid (in a lot of temperatures) Maintained by cis double bond (lowers mp), shorter fatty acid chains, cholesterol (increased firmness and integrity) In unsaturated lipids are always cis configuration. V shaped = packed less easily = lower melting point. Flexible carbon chain on the outside (non-polar part 1) = increased firmness (rigidity) and integrity of cell membrane. Translocases: integral membrane proteins, traverse the entire length of the membrane. Symport: transport 2 substances from one side to another. Antiport: transport 1 substance in 1 direction and opposite in opposite direction. 2 driving forces on molecules or ions:
