Carbohydrates are compounds that contain the elements carbon, hydrogen and oxygen. The basic building block of a carbohydrate is a monosaccharide, which is a simple sugar, for example:

  • Glucose
  • Fructose
  • Galactose

All three of these monosaccharides have the same chemical formula (C6H12O6)

Enzymes join two monosaccharides to form a disaccharide.

For example:

  • Glucose + Glucose = Maltose
  • Glucose + Galactose = Lactose
  • Glucose + Fructose = Sucrose

The general formula of disaccharides is C12H22O11

Polysaccharides are composed of long chains of monosaccharide units.

Many polysaccharides are insoluble, making them ideal for storage. Some examples of polysaccharides are:

  • Starch – An energy storage molecule in plants
  • Glycogen – An energy storage molecule in animals
  • Cellulose – Provides strength and support to plant cell walls

Carbohydrase enzymes break down disaccharides and polysaccharides into monosaccharides.