Discovery of the double
a double helix?
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.