A Scientist Recalls Cracking the Code : Biology: Francis H.C. Crick tells a CSUN audience how he and a fellow Nobel laureate discovered the molecular structure of DNA.

To the scriptwriter who heard and later dramatized Francis H.C. Crick’s story, it was a beautiful example of a classic pattern: boy meets girl, boy loses girl, boy gets girl.

With some slight modifications.

Just substitute Crick and fellow Nobel Laureate James D. Watson for the “boy,” and their landmark 1953 discovery of the molecular structure of DNA for the “girl,” and the result is a gripping tale of how two scientists in Cambridge, England, revolutionized the field of biology with their famous theory of the “double helix”--the entwined spirals found in each person’s genes that carry the building blocks of life.

To an enrapt audience on Thursday of more than 100 science teachers and students who packed the University Club at Cal State Northridge, Crick, now a white-haired fellow at the Salk Institute in La Jolla, described the tortuous route to the famous discovery. The address was part of a program sponsored by the National Science Foundation.

In well-modulated British tones, the 75-year-old scientist explained how the boy-meets-girl model later served as a paradigm for his and his colleagues’ work, later dramatized in the cable television movie “Race for the Double Helix.”

Although DNA was discovered in 1869 by German biochemist Friedrich Miescher, it’s molecular structure, a key to understanding how it functioned, remained an unsolved puzzle.

Enter Crick and Watson. They were certain that a helical structure somehow had to be involved in the makeup of DNA, or deoxyribonucleic acid. They got that much right.

But on the road to scientific epiphany, Crick said, they stumbled once with a misconceived theory that led nowhere and, at the same time, had to contend with another formidable would-be DNA suitor, two-time Nobel Prize-winner Linus Pauling.

In the end, the Cambridge team of Watson and Crick triumphed. Their double-helix model, which helped crack the genetic code, ranks among the greatest achievements in the history of science.

The discovery has had innumerable effects on daily life. The same day Crick spoke, a man charged with raping two college students was ordered released from County Jail after DNA tests showed that he was a victim of mistaken identity and could not have been the attacker.

And yet for all its import, the key to DNA turned out to be a disarmingly simple concept.

“It isn’t something deep and mathematical that’s the secret of life. It’s just a Tinker Toy,” Crick modestly told his listeners to a chorus of laughs.

Crick and the American-born Watson were engaged in amicable academic combat with Pauling, who at one point drove them to dejection when he hit upon a theory before they did.

But Pauling’s theory, Crick said, proved to be “a flop” because it mistakenly postulated a triple helix and incorporated a “really remarkable” error of chemistry that Pauling, a chemist by training, should have caught, Crick said.

“Of course, I’ve asked him in recent years, ‘Linus, how did you make such a mistake?’ ” Crick recounted. “He tells me he can’t remember--he doesn’t know. Looking back, it was unbelievable.”

But Crick also is not immune to memory lapses.

Crick admitted good-naturedly that when “Race for the Double Helix” was shot in 1987, he couldn’t recall the first DNA model--entirely erroneous--that he and Watson had fashioned. The filmmakers were forced to invent another wrong theory.

The movie contained other details that also deviated from the truth, but Crick, who has since channeled his interest toward study of the brain and of vision, said they were relatively minor points, such as where certain conversations took place or the portrayal of himself by actor Tim Pigott-Smith or Watson by Jeff Goldblum (“Far too manic--he was chewing gum all the time”).

The virtue of the critically acclaimed film, he said, instead was that audiences finally saw scientists portrayed not as white-coated, tunnel-visioned automatons but as humans with personal lives, who enjoy a rousing party with the best of ‘em.

To make his point, Crick showed a slide of an invitation to a costume party he and his wife threw many years ago at their Cambridge home. Coincidentally, the day of the “fancy dress” ball was Feb. 20--the exact same day as Thursday.

And the year?

“I can’t remember,” he said.