Freeman Bio Chapter 5 Outline

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Chapter 5
An Introduction to Carbohydrates

Carbohydrate – sugars, encompasses the monomers, called monosaccharides, small polymers called oligosaccharides, and large polymers called polysaccharides

5.1 Sugars as Monomers

1. How Monomers Differ
a. Monosaccharide – simple sugar, monomer
i. Carbonyl group serves as a distinguishing feature 1. At end of molecule, forms an aldehyde sugar (aldose) 2. In middle of molecule, forms a ketone sugar (ketose) ii. Presence of a carbonyl group along with multiple hydroxyl groups provides an array of functional groups in sugars iii. Number of carbons also varies in monosaccharides 3. Trioses (3), pentoses (5), hexose (6)

iv. Differences of structure is responsible for differences in function v. Rare to see sugars exist in linear forms
4. Tend to form rings in aqueous solution

5.2 Structure of Polysaccharides

1. Polysaccharides
a. Polysaccharides – polymers formed when monosaccharides are linked together i. Disaccharide - simplest polysaccharide of two sugars b. Simple sugars polymerized through condensation reactions between two hydroxyl groups, forming a glycosidic linkage through a covalent bond c. Since glycosidic linkages form between hydroxyl groups and every monosaccharide contains at least two hydroxyl groups, location and geometry of glycosidic linkages varies widely between polysaccharides d. α- linkages are easy for enzymes to break while β-linkages are difficult to break 2. Starch: A Storage Polysaccharide in Plants

e. Starch is made up of α-glucose monomers joined by glycosidic linkages ii. Mixture of unbranched amylose and branched amylopectin 3. Glycogen: A Highly Branched Storage Polysaccharide in Animals f. Glycogen performs the same storage role in animals that starch does in plants iii. Polymer of α-glucose

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