A-LEVEL AQA BIOLOGY NOTES
carbohydrates
Carbohydrates
- Monosaccharides are the simplest carbohydrates, consisting of only one sugar molecule (e.g. Glucose, Fructose & Galactose).
- Glucose is a hexose sugar with 2 isomers
- Disaccharides are sugars that are composed of two monosaccharides joined together in a condensation reaction, forming a glycosidic bond.
Amylose |
Value |
Maltose |
2 × α-glucose |
Sucrose |
α-glucose and fructose |
Lactose |
β-glucose and galactose |
- Polysaccharides are formed by many monosaccharides joined together.
- Amylose, amylopectin (starch) is the main polysaccharide energy store in plants, is composed of α-glucose.
- In animals, the polysaccharide energy store is called glycogen, composed of α-glucose.
- Cellulose is a structural component of plant cell walls, composed of long unbranched chains of b-glucose.