NOTES-chap 8

NOTES-chap 8 - Lipids and proteins are staple ingredients...

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Lipids and proteins are staple ingredients for membrane -- along with carbohydrates A phospholipid is an amphipathic molecule: has both hydrophobic and hydrophilic region -- most of the proteins of membranes have both regions Fluid mosaic model: the membrane is a fluid structure with various proteins embedded or attached to a double layer of phospholipids. Membrane is held together by hydrophobic intersections Most of the lipids and some of the proteins can drift laterally driven along cytoskeletal fibers by motor proteins A molecule rarely flip-flops transversely across the membrane Membrane remains fluid as temperature decreases until finally the phospholipids settle into a closely packed arrangement and the membrane solidifies i.e. bacon grease forms lard when it cools the membrane remains fluid to a lower temperature if it is rich in phospholipids with unsaturated hydrocarbon tails because of kinks in tail unsaturated hydrocarbons do not back together closely Integral proteins: penetrate the hydrophobic core of the lipid bilyaer . transmembrane proteins: completely span the membrane Peripheral proteins: are not embedded in the lipid bilayer at all; they are appendages bound loosely to the surface of the membrane On cytoplasmic side of the plasma membrane, some membrane proteins are held in place by attachment to the cytoskeleton On the exterior side, certain membrane proteins are attached to fibers of the extracellular matrix --- these attachments combine to give animal cells a stronger external framework
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This note was uploaded on 09/27/2011 for the course BIOL 101 taught by Professor Fevzidaldal during the Fall '08 term at UPenn.

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NOTES-chap 8 - Lipids and proteins are staple ingredients...

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