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   What is DNA?
    DNA timeline
    Discovery of the double helix
    Why a double helix?

Explaining DNA

What is DNA?
Chemically, DNA is a long polymer made up of a linear series of subunits known as nucleotides. Each nucleotide comprises a deoxyribose sugar, a phosphate group and a small organic molecule known as a base. The nucleotides come in four types, known as G, T, C and A.

Structurally, DNA is usually found as a double helix, with two strands wrapped around one another. However, DNA can adopt other configurations and it can also exist in single-stranded forms.

Functionally, DNA carries the information needed to construct and operate an organism. The information is coded in DNA in the order of the chemical letters of which DNA is made. This code is based on the order of nucleotide triplets (CTT, ATT CTG etc.) in a gene, which specify the order of particular amino acids in a protein. Other sections of DNA are responsible for switching genes on and off and regulating how much of each type of protein is made.

Inheritance is based on the transfer of genes (i.e. DNA) between generations.