THE BLUEPRINT OF LIFE


DNA

How does life reproduce itself? What causes a new individual of a species to resemble the old?

These are questions that biologists James D. Watson of the United States and Francis C. Crick of Great Britain were trying to answer.
In 1953, in the journal Nature, James Watson and Francis Crick announced their discovery of the double-helix structure of the DNA (deoxyribonucleic acid) molecule, found in all living cells. They showed it to be the mechanism by which life starts and is passed on from generation to generation.
The story was astonishing: In the two spirals of DNA lay the very secret of life, a grand staircase of genetic instructions. The strands of every DNA molecule consist of four bases-adenine, thymine, guanine and cytosine-whose sequence dictates what specific genetic information that particular molecule encodes. All inherited traits are encoded this way, permitting the reproduction of any living thing, be it a bacterium or an astronaut.

THE BASICS YOU NEED TO KNOW

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