Carbohydrates Objectives Distinguish among proteins carbohydrates lipids and

Carbohydrates

Objectives • Distinguish among proteins, carbohydrates, lipids and nucleic acids. (SPI 3210. 1. 3) – Identify or describe the skeleton structure of carbohydrates. – Identify the most metabolically important carbohydrate. – Identify and describe the carbohydrate form used to store excess energy resources in plants, animals and fungi. – Identify the major carbohydrate polymers and their respective biological functions. – Explain the biochemical processes that form polymers of simple sugars. • Identify positive tests for carbohydrates, lipids and proteins (SPI 3210. 1. 4) – Describe the biochemical test to detect simple sugars and starch

CARBOHYDRATES Mono-, di-, and poly- saccharides (Sugars)

Carbohydrate Skeleton Structure Have the general formula: (CH 2 O)n “Carbonated Water”

Monosaccharides (Single Sugars) Simple sugars with a backbone of three to seven carbon atoms. Best known monosaccharides sugars have six carbons (hexoses). Glucose Fructose Galactose

Dissacharides (Double Sugars) Two monosaccharide (single sugars) joined by dehydration synthesis. -Lactose Galactose + Glucose Found in milk. -Maltose Glucose + Glucose Forms in human digestive tract during starch digestion. -Sucrose Glucose + Fructose Transported within plants.

Polysaccharides Chains of glucose molecules or modified glucose molecules.

Polysaccharides (carbohydrates) Used For Energy Storage Starch. Found in plants. Straight chain of glucose molecules Few side branches. Glycogen. Found in animals (called “animal starch”). Highly branched polymer of glucose Many side branches

Polysaccharides (carbohydrates) Structural Forms Cellulose - Primary constituent of plants cell walls; Not easily digested; . – Grazing animals can digest cellulose due to special stomachs and bacteria. – Cotton - nearly pure cellulose. Chitin - Found in exoskeleton of animals like lobsters and insects; Polymer of glucose with amino acid attached to each.

Chitin (carbohydrates) Structural Forms Modified form of cellulose

Test for Simple Sugars Benedict’s Reagent + Heat (boiling) Positive = Brick Red/Orange

Test for Starch Lugol’s Iodine

Review • Describe the skeleton structure of carbohydrates. • What is the most metabolically important carbohydrate? • Describe the carbohydrate form(s) used to store excess energy resources in plants, animals and fungi. • Identify the major carbohydrate polymers and their respective biological functions. • How are polymers made from simple sugars.