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| DNA Helix |
Every living thing on Earth, every plant and animal, shares the most fundamental structure of life. We call it deoxyribonucleic acid (say "dee-ox-ee-rye-boh-new-CLAY-ic A-sid"), or DNA.
Scientists have known about DNA since 1871. But an unassuming scientific paper published by James Watson and Francis Crick in 1953 revolutionized the notion of life itself by unveiling the DNA molecule's form: the double helix. "This structure has novel features which are of considerable biological interest," they wrote. Together with Maurice Wilkins, Watson and Crick went on to win the Nobel Prize in 1962 for their discovery.
This is DNA
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| Vial of DNA |
The stringy substance in this vial may not look important, but we wouldn't exist without it. It's human DNA.
This DNA came from several anonymous donors, and it was processed in the laboratory in order to create a sample visible to the naked eye. Teams of scientists studied similar specimens to decipher the human genome—the complete set of chemical instructions needed to create a person.
The Immense Human CodeIn all, the human genome contains 3.2 billion units of DNA code, arranged in a fixed sequence that defines the human species.
Four chemical components—adenine, thymine, guanine and cytosine, commonly abbreviated as A, T, G, and C—make up the bases of the genetic code, the rungs of the double-helix ladder. If the A's, T's, G's, and C's along one side of the DNA double helix replaced all of the letters and numbers in the Manhattan telephone book, they would fill the 140 volumes. Believe it or not, your genetic information—the human genome—is packed into the nucleus of virtually every cell in your body.
Colors of Code
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| DNA Sequencing Array |
This rainbow array graphically represents the enormous volume of information in the human genome. Each color stands for one of the four chemical components, or bases, of DNA—adenine, thymine, guanine, and cytosine, commonly abbreviated as A, T, G and C.
A laser scans DNA samples tagged with four colors: A=green, T=red, G=yellow and C=blue. A computer translates each color into the appropriate letter. Scientists then interpret and store the sequence in a computerized database.
At this speed, scrolling through all 3.2 billion units of the human genome would take about 11 months.
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