A carbohydrate is a polymer made from monosaccharides. They contain the elements carbon, hydrogen and oxygen. The basic building block is a monosaccharide, which is a simple sugar, for example:

  • Glucose
  • Fructose
  • Galactose

They all 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 long chains of monosaccharides.

As polysaccharides are insoluble, they are very useful as storage molecules. Some examples of them are:

  • Starch – Store of energy in plants
  • Glycogen – Store of energy in animals
  • Cellulose – Provides strength and support to the cell wall

Carbohydrase enzymes break down disaccharides and polysaccharides into monosaccharides.