CarbohydratesObjectives: Ability to define the term ‘biological

chemicals’ Understand the structure & classification of

carbohydrates Knowledge of the functions of

carbohydrates within the body

Biological Chemicals

The chemical basis of living things Carbohydrates Lipids Proteins Water Nucleic acids Enzymes

CarbohydratesWhat are they? Sugars & starchesWhat are they made up from? Carbon, hydrogen & oxygenWhat proportions of each? 1: 2 : 1

Monosaccharides Simplest of carbohydrates Sweet-tasting Dissolves in water Straight chain or ring structure Example: Glucose

Structure of Monosaccharides Glucose – formula C(6)H(12)O(6) Can be represented by a

STRAIGHT CHAIN Or as a 6-sided structure called a

PYRANOSE RING Most molecules exist as rings

rather than single chains

Disaccharides Double-sugar Sweet, soluble & crystalline 2 monosaccarides combine together

This is called a glycosidic bond Examples:

Maltose = glucose + glucose

Sucrose = glucose + fructose

Lactose = glucose + galactose

Polysaccharides Many monosaccarides join together Chains may be folded & compact Ideal for storage Examples: starch & glycogen However, not all used for storage Example: cellulose – strengthens &

supports cell walls

Functions of carbohydrates

Principally a respiratory substrate

i.e. oxidized to release energyCell division

Muscle contraction

Sources of carbohydrates Starch, sugars & cellulose are the

main carbohydrates we eat Reserves stored as glycogen in

liver & skeletal muscles About 50% of the average diet More active = higher percentage Examples:Rice, potatoes, wheat, cereal grain