1. Carbohydrates

2. What are Carbohydrates?  Put simply…hydrocarbons.  Empirical Formula C n H 2n O n  Divided into three groups  Monosaccharides  Disaccharides  Polysaccharides

3. Monosaccharides  Monomers…single sugar molecules.  Let’s build glucose and fructose.  How are the molecules different?  What functional groups are present?

4. 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.

5. Disaccharides  Two monosaccharides joined by a glycosidic bond. (ether)  A water molecule is generated in the process of bond formation. (condensation polymerization)

6. 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.

7. 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.

8. 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)

9. 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.

10. Pectin  Pectin is a polysaccharide made of galacturonic acid (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.