It's life's instruction book, enlarged

WASHINGTON - The first exhibit visitors will see at a new Smithsonian show looks like a photo of a giant orange golf ball. The caption says: "This WAS you."

Smaller type identifies the ball as an enlarged human egg cell, the type of cell which eventually develops into a human embryo.

The resulting person, the exhibition explains, consists of trillions of cells. In these cells are copies of the show's theme: "Genome: The Secret of How Life Works."

The show celebrates the 50th anniversary of the discovery of DNA, which carries the genes that determine human traits. It opened to the public Saturday at the Arts and Industries Building and will be on view through Jan. 4 before starting a five-year tour of 15 U.S. cities.

The genome is a genetic map. The exhibit uses oversize displays and interactive activities to explain its complexities.

Visitors to the exhibit can, for instance, track the genes responsible for red hair or dimples or particular hereditary illnesses, said Anne Kinsey, project manager for Clear Channel Exhibitions, which put together the show.

Mother and father each contribute half a person's genes. Chance also plays a role. An interactive exhibit uses a slot machine to illustrate the myriad genetic possibilities. Each time the handle is pulled, the rolling wheels of pictures come up with a new combination.

Other traits that genes control will take years to explore. They often work in combinations and biologists aren't sure how many there are: most think about 20,000, others think the number will turn out to be twice as many or more.

DNA resembles a spiral staircase, a pair of twisted strings holding together "steps" - which are pairs of molecules called bases. The different combinations of the bases on the steps make up the genes.

The strings are coiled in the famous double helix, traced at Britain's Cambridge University in 1953. The discovery is sometimes called the greatest in 20th century biology. Two Britons, Francis H.C. Crick and Maurice H.F. Wilkins, and an American, James D. Watson, shared a Nobel prize for it.

Their work has turned research in new directions. Before it, the exhibit says, biologists had to examine tiny units of life individually, as if a forester were limited to examining tree after tree. Now they have a whole map of the woods.

© 2006 • All Rights Reserved • St. Petersburg Times
490 First Avenue South • St. Petersburg, FL 33701 • 727-893-8111

Contact the Times | Privacy Policy
Standard of Accuracy | Terms, Conditions & Copyright