Lecture 3- cell membranes

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Unformatted text preview: :25 membrane are composed of primarily polar amino acids Gardiner 2013 (hydrophillic) 10:25 Gardiner 2013 1202B – On the cytoplasmic side, some membrane proteins connect to the cytoskeleton. – On the exterior side, some membrane proteins attach to the fibers of the extracellular matrix. BIOLOGY • One role of membrane proteins is to reinforce the shape of a cell and provide a strong framework. 23 Membranes are mosaics of structure and function !Fluid*mosaic*model!*current*view*of*membrane* structure !The*membrane*proposes*that*membranes*consist*of* proteins*within*a*mixture*of*lipid*molecules* !The*mosaic*aspect*refers*to*the*fact*that*most* membranes*contain*an*assortment*of*different*types*of* protein;*proteins*involves*in*transport*and*attachment,* signal*transduction*etc !Blue*dumbell*shaped!*integral*proteins !Glycolipids*and*glycoproteins*are*formed*by*lipid*and* Fig. 5.1 protein*groups*binding*to*carbohydrate*groups !Membrane*is*complex 8 Membrane carbohydrates are important for cell-cell recognition • The membrane plays the key role in cell-cell recognition. – Cell-cell recognition is the ability of a cell to distinguish one type of neighboring cell from another. • important in cell sorting and organization as tissues and organs in development. • basis for rejection of foreign cells by the immune system. – Cells recognize other cells by keying on surface molecules, often carbohydrates, on the plasma membrane. !How&to&get&things&in&and&out&of&the&cell?&must&be&able& Getting Across the Membrane BIOLOGY Cell Membranes to&cross&membrane 1202B 10:25 Gardiner 2013 26 Membrane’s molecular organization selective permeability !Many&small&molecules&can&get&across&the&barrier !Others&can&not&get&across;&other&methods&developed&to& help • A steady traffic of small molecules and ions moves across the plasma membrane in both directions. – sugars, amino acids, and other nutrients enter a muscle cell and metabolic waste products leave. – absorbs oxygen and expels carbon dioxide. – regulates concentrations of inorganic ions, like Na+, K+, Ca2+,...
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