How to build DNA

Peter Artymiuk, Wellcome Images

This twisting spiral shows the chemical structure of DNA.

For years scientists tried to find how information was passed down, or inherited, from parent to child.

John Sulston

DNA is a long molecule made up of four different nucleotides or bases, a ribose sugar and phosphate.

Sounds complicated, but for a molecule supposed to carry all the instructions for life it is a bit too simple for some. However experiments on bacteria showed that deoxyribonucleic acid was indeed responsible for passing instructions to the next generation.

Like a spiraling ladder, the double stranded DNA has ‘rungs’ formed by the nucleotides or base pairs. The chemical bases that form these pairs are very specific when building the molecule;
adenine (A) only bonds with thymine (T), while
cytosine (C) only links with guanine (G).

Encoded within the sequence of these bases are genetic instructions to produce the molecules that build your body and carry out the functions of the cell.

“It was so simple, so elegant, that it almost had to be right.”
James Watson

“How remarkable that an invisibly thin thread of DNA carries the information to make a human being. And how marvellous that we understand”
Sir John Sulston

For DNA to be inherited it must first be copied – see how this ingenious structure replicates itself.

Copyright 2003 Howard Hughes Medical Institute

Flash required to play video
Download captions

What is the link between chromosomes and DNA? It is all a matter of scale, watch as the chromosome unfolds.

Copyright 2003 Howard Hughes Medical Institute

Flash required to play video
Download captions

Indigo Instruments Inc.

Human genome project

Find out more about who was involved and how they decoded the sequence.

Read More

Genome explorer

Browse the human genome and meet some of the people researching it

Read More

DNA Function

How does a pattern of four bases produce all the instructions to create a human?

Read More

Latest Poll

Total number of responses 40
View this story

news and views

Have your say on DNA making the news