monosaccharaides that may be straight or branchedGlycocalyx- extensive sugary coat formed by the carbohydrate portions of the glycolipids and glycoproteins•Patterns of carbohydrates in the glycocalx varies from one cell to anotherGlycocalx acts like a molecule signature that enables cells to recognize one anotherwhite blood cell ability to detect foreign glycocalx= immune response to destroy invading organisms•Glycocalx enables cells to adhere to one another in some tissues and protects cells from being digested by enzymes in the extracellular fluid•Hydrophilic properties of glycocalx attract a film of fluid to the surface of many cells makes red blood cells slippery as they flow through narrow blood vessels and protects cells that line the airways and gastrointestinal tract from drying outc.Functions of Membrane Proteinsc.i.Types of lipids in cellular membrane vary only slightymembranes of different cells and various intracellular organelles have remarkably different assortments of proteins that determine many of the membrane’s functionsIon Channel (integral)•Pores or holes , filled with water, that specific ions (ex: K+ potassium) can flow through to get in or out of the cell•Most are selectiveallow only a single type of ion to pass throughCarriers (integral)
•Transports specific substances or ion across membrane by membrane by changing shape•AKA transporters •EX: amino acids needed to synthesize new proteins enter body cells via carriersReceptor (integral)•Cellular recognition sites•Each type of receptor recognizes and binds a specific type of molecule + alters the cell’s function in some way•Ligand- specific molecule that binds to a receptor •EX: insulin receptors bind hormone insulinEnzyme (integral and peripheral)•Catalyzes specific reaction inside or outside cell depending on which direction active site facesLinker (integral and peripheral)•Anchors filaments inside and outside the plasma membrane, providing structural stability and shape for the cell•May also participate in movement of the cell or link two cells togetherCell Identity Marker (glycoprotein or glycolipid)•May enable cell to recognize other cells of the same king during tissue formation •Recognize and respond to foreign cells that are potentially dangerous•EX: ABO blood type markers, in blood transfusion, blood type must be compatible with own or red blood cells may clump togetherc.ii.Peripheral proteins help support the plasma membrane, anchor integral proteins and participate in mechanical activities such as moving materials and organelles within cells, changing cell shape in dividing and muscle cells, and attaching cells to one anotherd.Membrane Fluidity d.i.
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- Fall '13