Chapter 3 Carbohydrates, Lipids, & Proteins Carbohydrates Mono/Disaccharides, Reactions, & Polysaccharides Sugars (2 types) 1. Monosaccharides 2. Disaccharides • Three common disaccharides: Two important reactions in making and breaking down molecules 1. Dehydration reaction (IB calls condensation reactions) 2. Hydrolysis http://www.tvdsb.on.ca/westmin/scien ce/sbioac/biochem/condense.htm Polysaccharides (3 types) 3 Types of Polysaccharides 1. Starches • polymers of glucose • the storage polysaccharide for plants • rice, wheat, potato, and corn are major sources of starch in the human diet. • starches are insoluble in water and thus can serve as storage depots of glucose 2. Glycogen • a short-term storage polysaccharide for animals • highly branched glucose units put together that are broken down to meet energy demands of the body 3. Cellulose • most abundant polysaccharide on earth • the major structural material of which plants are made (wood and plant fibers) • insoluble and has great tensile strength because the hydroxyls (-OH) are reversed on the carbon compared to other polysaccharides • the polymers can be drawn together into dense, cable-like strands called microfibrils that can then be organized into fibrils • most organisms can’t break cellulose down into simple sugars because they don’t have the enzyme cellulase which is necessary to hydrolyze the glycosidic linkages. • as a result, plant cell walls are among the strongest of biological structures.