What is DNA?

The key structural components of DNA

DNA (deoxyribonucleic acid) is a long polymer made up of nucleotides, which are composed of a sugar-phosphate group and one of 4 bases: Adenine (A), Cytosine (C), Guanine (G) and Thymine (T). It is the sequence arrangement of these 4 bases (ACGT), which comprises the genetic code.  This code, with a few exceptions, is the same for all organisms so we can directly compare DNA sequences obtained from species ranging from amoebas to zebras.

In living organisms DNA is not a single molecule but rather a pair of molecules entwined in the shape of a double helix.

The main role of DNA is the long term storage of heritable information. It carries the instructions needed to make the structural components of living organisms e.g. proteins.

  • The DNA segments that code those instructions are called genes
  • Thousands of genes and millions of bases are organised into structures called chromosomes.
  • The set of chromosomes within a cell is called the genome

A simple way to think about genes and proteins is like building a house: genes act as the house’s architectural blueprint and the proteins as the bricks and mortar that are used to build it.

Queensland Museum's Find out about... is proudly supported by the Thyne Reid Foundation and the Tim Fairfax Family Foundation.