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In: Facts In the Cell
What is DNA?
DNA or deoxyribonucleic acid is a long molecule that contains our unique genetic code. Like a recipe book it holds the instructions for making all the proteins in our bodies.
Your genome is made of a chemical called deoxyribonucleic acid, or DNA for short.
DNA contains four basic building blocks or 'bases': adenine (A), cytosine (C), guanine (G) and thymine (T).
The order, or sequence, of these bases form the instructions in the genome.
DNA is a two-stranded molecule.
DNA has a unique 'double helix' shape, like a twisted ladder.
An illustration to show the double helix structure of DNA.
Image credit: Genome Research Limited
Each strand is composed of long sequences of the four bases, A, C, G and T.
The bases on one strand of the DNA molecule pair together with complementary bases on the opposite strand of DNA to form the 'rungs' of the DNA 'ladder'.
The bases always pair together in the same way, A with T, C with G.
Each base pair is joined together by hydrogen bonds.
Each strand of DNA has a beginning and an end, called 5' (five prime) and 3' (three prime) respectively.
The two strands run in the opposite direction (antiparallel) to each other so that one runs 5' to 3' and one runs 3' to 5', they are called the sense strand and the antisense strand, respectively.
The strands are separated during DNA replication.
This double helix structure was first discovered by Francis Crick and James Watson with the help of Rosalind Franklin and Maurice Wilkins.
The human genome is made of 3.2 billion bases of DNA but other organisms have different genome sizes.
This page was last updated on 2016-01-25
What is a genome?
A genome is an organism's complete set of genetic instructions. Each genome contains all of the information needed to build that organism and allow it to grow and develop.
What is DNA replication?
DNA replication is the process by which DNA makes a copy of itself during cell division.
What does DNA do?
The DNA code contains instructions needed to make the proteins and molecules essential for our growth, development and health.
Giants in genomics: Francis Crick
Francis Crick and his American colleague, James Watson, discovered the double helix structure of DNA. For this fundamental finding Francis, James and Maurice Wilkins were awarded the Nobel Prize for Physiology or Medicine in 1962.
Giants in genomics: James Watson
James Watson and his British colleague Francis Crick discovered the double helix structure of DNA. For this fundamental finding James, Francis and Maurice Wilkins were awarded the Nobel Prize for Physiology or Medicine in 1962.
Giants in genomics: Rosalind Franklin
Rosalind Elsie Franklin was a British biophysicist and X-ray crystallographer whose fundamental research was critical to Watson and Crick's discovery of the structure of DNA.
The discovery of DNA
How was DNA first discovered and who discovered it? Read on to find out...
Revealing DNA as the molecule of life
How was DNA discovered to be the carrier of genetic information? Read on to find out...
Unravelling the double helix
The discovery of the structure of DNA by James Watson and Francis Crick in 1953 is one of the most famous scientific discoveries of all time.
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