DNA

Life on this planet is built up of proteins, encoded for by genetic material made of a substance called deoxyribonucleic acid (DNA).

DNA is shaped as a three-dimensional structure called a double helix, which is pictured opposite.

In eukaryotic organisms DNA is arranged in units called genes which lie within the nucleus of cells along strands known as chromosomes.

There is therefore a hierarchy of organization from chromosomes to genes to DNA to the fundamental nitrogenous bases and sugar and phosphate molecules.

An animation illustrates this hierarchy.