1. Carbohydrates
Simple Sugars

2. Learning Objectives
. Distinguish between monosaccharides, disaccharides and polysaccharides
(glycogen and starch – amylose and amylopectin) and relate their structures to their roles in providing and storing energy (β-glucose and cellulose are not required in this topic).

3. Learning objectives
Describe how monosaccharides join to form disaccharides (sucrose, lactose and maltose) and polysaccharides (glycogen and amylose) through condensation reactions forming glycosidic bonds, and how these can be split through hydrolysis reactions.

4. Carbohydrates Functions: Energy source
Energy store e.g. starch or glycogen
Structural material e.g. cellulose
Elements made of:
Carbon, hydrogen, oxygen
General formula
Cn(H2O)n

5. CARBOHYDRATES Simple SUGARS POLYSACCHARIDES MONOSACCHARIDES
DISACCHARIDES
E.g.
Starch and
Glycogen
Cellulose
E.g. Glucose, Fructose,
Galactose
E.g. Sucrose,
Lactose and Maltose
ENERGY
SOURCE
ENERGY
STORAGE
STRUCTURAL
– component of
plant cell walls

6. Monosaccharides The simplest carbohydrates ‘single sugars’
Contain between 3 and 6 carbon atoms
3 C’s = Triose sugar e.g. glyceraldehyde
5 – pentose sugar e.g. ribose & deoxyribse
6 – hexose sugar e.g. glucose & fructose,
Properties
Water soluble
Sweet
Form crystals

7. α- Glucose

9. The glycosidic bond
Monosaccharides can be monomers for bigger molecules
When two monosaccharides join together a glycosidic bond is formed
Why is this called a condensation reaction?

10. Disaccharides Double sugars made from 2 monosaccharides
Formed by CONDENSATION reaction
Each mono joined by a GLYCOSIDIC bond
Examples
Maltose = 2 x α-glucose
Sucrose = glucose + fructose
Lactose = glucose + galactose

11. Hydrolysis reaction