CHAPTER_7 - CHAPTER 7 selective permeability- allows some...

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CHAPTER 7 selective permeability- allows some substances to cross -The most abundant lipids in membranes are phospholipids - amphipathic molecule - has hydrophillic and hydrophobic region- phospholipids - fluid mosaid model - membrane is fluid structure with mosaic of various proteins embedded in or attached to double layer of phospholipids FLUIDITY OF MEMBRANES -membrane is held together primarily by hydrophobic interactions -Rare for molecule to transverse membrane- hydrophillic region has to go through hydrophobic region -Some membrane proteins are immobile due to their attachment to cytoskeleton -Membrane remains fluid to lower temperature if its rich in unsaturated phospholipid hydrocarbon tails -Cholestrol makes the membrane less fluid by restraining the movement of phospholipids but also lowers the temperature required for the membrane to solidify -Temperature buffer MEMBRANE PROTEINS AND FUNCTIONS -different cells contain different sets of membrane proteins - integral proteins - penetrate the hydrophobic core of the lipid bilayer -many are trasmembrane proteins that span the membrane -hydrophobic regions of intergral proteins consist of one or more stretches of nonpolar amino acids - peripheral proteins- are not embedded in lipid bilayer- are appendages loosely bound to the surface of the membrane -Some membrane proteins are held in place by attachement to cytoskeleton on cytoplasmic side -On exterior side, attached to extracellular matrix FUNCTION OF MEMBRANE PROTEINS -transport -enzymatic activity -signal transduction -cell-cell recognition -intracellular joining -attachement to the cytoskeketon and extracellular matrix MEMBRANE CARBOHYDRATES IN CELL-CELL RECOGNITION -The cells recognize other cells by binding to surface molecules- often carbohydrates
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This note was uploaded on 07/14/2009 for the course BILD BILD1 taught by Professor Bever during the Spring '08 term at UCSD.

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CHAPTER_7 - CHAPTER 7 selective permeability- allows some...

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