James Watson shows Alan how he came to discover the double helix.

Analogies help clarify the difficult concepts in genetics. We compare base pairs, which make up genes, to "building blocks," and genes themselves, which tell cells what do to, to "blue prints." And the human genome, containing all the information needed to build and operate a human being, often gets compared to a book if not an entire library. All these metaphors make it easy to forget that genes are real things.

At the DNA Learning Center on Long Island, Alan Alda gets to meet his own genes face to face. First, he swishes some mouthwash around, sloughing off thousands of cheek cells, each of which contains all the information (three billion letter's worth!) needed to build an Alan Alda. Then, using enzymes and a centrifuge to break up and separate the cells, Alan is left with a vial of his own DNA, which looks clear and slightly gooey to the naked eye.

Alan's DNA

DNA's elegant double helix structure was first discovered by James Watson and Francis Crick in 1953. At Watson's office at Cold Spring Harbor Laboratory on Long Island, Alan talks with the Nobel Laureate about those heady days of discovery when it all fell into place, and the field of molecular biology took off. We've come a long way since, but not necessarily far enough for James Watson.

"I mean it's going good and it's great," Watson tells Alan. "But I'll only be truly happy if we stop cancer or stop schizophrenia."

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Profile: Eric Lander
Falling in Love with DNA