The DNA revolution may be just too big to take in: beyond words, even 50 years on. Think of four chemical bases coupled exclusively to each other, adenine with thymine, guanine with cytosine, in a double helix. Then think of this double helix having the power to unwind and duplicate, to make new helixes. So far, so simple. The structure spells out a gene that makes a protein, and makes more DNA.
But like the double helix itself, the challenges divide into questions of scale and complexity. In the nucleus of one cell of one human, tiny braids of DNA twist into two sets of 23 chromosomes. These add up to 3 billion bases, or 200 telephone books of information, or 750,000 pages of typescript, or a procession of nucleotides, which, if read aloud at the rate of one a second, would take almost 100 years to recite. The human ...
