text: The composition of the human body can be classified as follows:
  *Water
  *Proteins
  *Fats (or lipids)
  *Hydroxyapatite in bones
  *Carbohydrates such as glycogen and glucose
  *DNA and RNA
  *Inorganic ions such as sodium, potassium, chloride, bicarbonate, phosphate
  *Gases mainly being oxygen, carbon dioxide
  *Many cofactors.
  The estimated contents of a typical 20-micrometre human cell is as follows: