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Published byRuth Harvey Modified over 9 years ago
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amylose
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Amylopectin or glycogen
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Glycogen and Amylopectin Structures Glycogen and Amylopectin are (1-4) chains with with (1-6) branches AmylopectinGlycogen Polysaccharides
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cellulose
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Carbohydrates – Complex (Polysaccharides) Cellulose = polysaccharide found in plant cell walls Cellulose fibers Macrofibril Microfibril Chains of cellulose
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N-acetyl-D-glucosamine units in ( -->4) linkage chitin
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Glycoprotein Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide side-chains. The process of attaching the glycans is known as glycosalation. The sugar groups attached to glycoprotein can assist in protein folding or improve a proteins’ stability.
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Functions of Glycoproteins FunctionGlycoprotein Structural MoleculeCollagen Lubricant and Protective AgentMucins Transport MoleculeTransferrin, ceruloplasmin Immunologic MoleculeImmunoglobins, histocompatibility antigens EnzymeVarious, e.g alkaline phosphatase Cell Attachment-recognition siteProteins involved in cell to cellc ommunication Interact with specific carbohydratesLectins, selectins (cell adhesion lectins), antibodies
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Functions of Glycoproteins FunctionGlycoprotein ReceptorVarious Proteins in hormone and drug action Affect folding of certain proteinsCalnexin, Calreticulin Regulation of developmentNotch and its analogs, key proteins in development Hemostasis (and thrombosis)Specific glycoproteins on the surface membranes of platelets
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glycosaminoglycans of extracellular matrix lubricants in the synovial fluid of joints cartilage, tendons, ligaments a variety of horny structures formed of dead cells: horn, hair, hoofs, nails
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A typical tetrasaccharide linker (blue) connects a glycosamino-glycan—in this case chondroitin 4-sulfate (orange)—to a Ser residue (pink) in the core protein. The xylose residue at the reducing end of the linker is joined by its anomeric carbon to the hydroxyl of the Ser residue. Proteoglycans: cell surface or extracellular matrix
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One very long molecule of hyaluronan is associated noncovalently with about 100 molecules of the core protein aggrecan Proteoglycan aggregate of the extracellular matrix
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Interactions between cells and the extracellular matrix with binding sites for both integrin and the proteoglycan
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linkages in glycoproteins Ser/thr
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Bacterial lipopolysaccharides
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Lectins, found in all organisms, are proteins that bind carbohydrates with high specificity cell-cell recognition, signaling, adhesion processes, intracellular targeting, deterrent to insects
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lectin-ligand interactions in lymphocyte movement to the site of an infection Stronger interaction near the site of inflammation
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Helicobacter pylori Interaction between a bacterial surface lectin and an oligosaccharide of the gastric epithelium
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Recognition and adhesion at the cell surface
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