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Carbohydrates. What are Carbohydrates?. Put simply…hydrocarbons. Empirical Formula C n H 2n O n Divided into three groups Monosaccharides Disaccharides Polysaccharides. Monosaccharides. Monomers…single sugar molecules. Let’s build glucose and fructose. How are the molecules different?
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What are Carbohydrates? • Put simply…hydrocarbons. • Empirical Formula CnH2nOn • Divided into three groups • Monosaccharides • Disaccharides • Polysaccharides
Monosaccharides • Monomers…single sugar molecules. • Let’s build glucose and fructose. • How are the molecules different? • What functional groups are present?
Monomers in Use • Ribose and 2-deoxyribose are pentoses • Used in DNA and RNA • Glucose, Galactose, and Fructose are hexoses • Used in plants and animals for energy • Build into larger biological molecules like insulin.
Disaccharides • Two monosaccharides joined by a glycosidic bond. (ether) • A water molecule is generated in the process of bond formation. (condensation polymerization)
Disaccharides in Use • Sucrose • Table Sugar • Let’s build it! Join the glucose and fructose from earlier. • Lactose • Milk sugar: glucose and galactose • Lactose intolerant people lack the enzyme needed to break lactose’s glycosidic bond. • Invert Sugar • Bees use enzymes to break sucrose’s glycosidic bond to create invert sugar, which is the sweet flavor in honey.
Polysaccharides • Strings of more than 20 monosaccharides. • Starch • Major source of food calories consumed by people • Amylose (in rice!)= linear polysaccharide • Amylopectin = branched polysaccharide • Glycogen = highly branched, stored in muscles and liver until converted to fat for long term storage.
Alpha and Beta Linkages • Starch and Cellulose are made of glucose. • 2 isomer forms for linkages- alpha and beta. • Starch has alpha linkages. (cis) • Cellulose has beta linkages. (trans)
Food uses of Carbohydrates • Reducing sugars react with amino acids in the Maillard Reaction (causes browning) • Polysaccharides bind water to thicken liquids into gels. • Used to stabilize suspensions, emulsions.
Pectin • Pectin is a polysaccharide made of galacturonicacid (galactose) molecules with beta linkages. • Found in green apples, lime peel, lemon peel • When heated with sugar at low pH, branched polymerization occurs to create a thick gels.