lecture_20legge - aldehyde = aldose Triose Tetrose 2(n-3...

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11/13/2009 1 Sugars 10/29/09 Carbohydrate and sugar structure Carbohydrates or saccharides are essential components of living organisms. (C•H 2 O) n Where n=3 or greater. A single saccharide is called a monosaccharide. Oligosaccharide is a few linked monosaccharides and are at time associated with proteins (glycoproteins) or lipids (glycolipids) Polysaccharides consist of many monosaccharides i.e. cellulose or glycogen Monosaccharides (D-aldoses) The Fischer convention, the basis for the D- configuration in sugars comes from D-glyceraldhyde’s configuration around its asymmetric carbon. Note there are 2 (n-2) stereoisomers. CHO OH H H HO OH H CHO OH H H HO OH H 1 2 3 4 1 2 3 4 OH H CH 2 OH H HO CH 2 OH D-glucose L-glucose 5 6 5 6 Epimers differ in configuration around one carbon atom i.e. D- glucose and D-mannose but D-galactose and D-mannose are not epimers as they vary around two carbon atoms. Monosaccharides (D-aldoses) Epimers Not Epimers Carbohydrates are classified as to the nature of the carbonyl group : ketone = ketose
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Unformatted text preview: aldehyde = aldose Triose Tetrose 2 (n-3) stereoisomers of ketoses c.f. 2 (n-2) Pentose Hexose stereoisomers of aldoses 11/13/2009 2 Monosaccharides can form ring structures Note that unlike condensation reactions there is NO loss of a water molecule in these cyclization reactions. α-below plane β-above plane Glycosidic bonds are between two sugars They can either be in the α or β configuration and can be linked through the 1-2, 1-4 or 1-6 linkage Note loss of water from condensation reaction above. 11/13/2009 3 Sugar Polymers The Polysacchrides • Energy Storage – Starch α-amylose and amypectin Structura • Structural – Cellulose and Chitin • Glycosaminoglycans • Proteoglycans α-amylose (starch) / Cellulose (poly β-glucose) Glycosaminoglycans & Proteoglycans Bacteria Cell Walls Peptidoglycan Next Lecture Tuesday 11/03/09 Glycolysis Glycolysis I...
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This note was uploaded on 02/22/2011 for the course BCHS 3304 taught by Professor Johnson during the Spring '08 term at University of Houston.

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lecture_20legge - aldehyde = aldose Triose Tetrose 2(n-3...

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