create semi permeable channels lipid bilayer membrane protein channels in lipid

Create semi permeable channels lipid bilayer membrane

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create semi-permeable channels lipid bilayer membrane protein channels in lipid bilyer membrane This former model of the cell membrane is no longer correct This is the currently accepted structure of the cell membrane
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AP Biology 2007-2008 Why are proteins the perfect molecule to build structures in the cell membrane?
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AP Biology Classes of amino acids What do these amino acids have in common? What do these amino acids have in common? nonpolar & hydrophobic nonpolar & hydrophobic
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AP Biology Classes of amino acids What do these amino acids have in common? What do these amino acids have in common? polar & hydrophilic polar & hydrophilic
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AP Biology Proteins domains anchor molecule Within membrane nonpolar amino acids hydrophobic anchors protein into membrane On outer surfaces of membrane in fluid polar amino acids hydrophilic extend into extracellular fluid & into cytosol Polar areas of protein Nonpolar areas of protein
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AP Biology NH 2 H + COOH Cytoplasm Retinal chromophore Nonpolar (hydrophobic) -helices in the cell membrane H + Porin monomer -pleated sheets Bacterial outer membrane proton pump channel in photosynthetic bacteria aquaporin = water channel in bacteria function through conformational change = protein changes shape function through conformational change = protein changes shape Examples H 2 O H 2 O H + H +
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AP Biology Many Functions of Membrane Proteins Outside Plasma membrane Inside Transporter Cell surface receptor Enzyme activity Cell surface identity marker Attachment to the cytoskeleton Cell adhesion “Antigen” “Channel”
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AP Biology Membrane Proteins Proteins determine membrane’s specific functions cell membrane & organelle membranes each have unique collections of proteins Classes of membrane proteins: peripheral proteins loosely bound to surface of membrane ex: cell surface identity marker ( antigens ) integral proteins penetrate lipid bilayer, usually across whole membrane transmembrane protein ex: transport proteins channels, permeases (pumps)
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AP Biology Cell membrane must be more than lipids… In 1972, S.J. Singer & G. Nicolson proposed that membrane proteins are inserted into the phospholipid bilayer It’s like a fluid… It’s like a mosaic… It’s the Fluid Mosaic Model !
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AP Biology The membrane is a collage of proteins & other molecules embedded in the fluid matrix of the lipid bilayer Extracellular fluid Cholesterol Cytoplasm Glycolipid Transmembrane proteins Filaments of cytoskeleton Peripheral protein Glycoprotein Phospholipids 1972, S.J. Singer & G. Nicolson proposed Fluid Mosaic Model
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  • Fall '16
  • idk
  •  Salts,  Membrane

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