What is 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.
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