Cetus paid its chemist $10,000 for PCR, then sold the patent for $300 million

Kary Mullis was a chemist at Cetus, a pioneering Bay Area biotechnology company, making oligonucleotides in the spring of 1983 when, as he drove through the California mountains one night, the polymerase chain reaction came to him. Instead of copying DNA once, the reaction would copy it repeatedly: two primers bracket the target, a polymerase extends between them, heating separates the strands, and each cycle doubles the haul. The Nobel committee later described the procedure as very simple — in theory needing only a test tube and some heat.

Presented in 1985, PCR spread with astonishing speed; by 1993 the Nobel committee could already call it one of the most widespread methods of DNA analysis. It let laboratories diagnose viral and bacterial infections without the slow culture of microorganisms — HIV detection was an early application — localize the genetic alterations behind hereditary disease, extract decisive evidence from a single drop of blood at a crime scene, and read DNA from extinct insects in amber. The committee's verdict on the Human Genome Project was blunt: without PCR it would hardly have been realistic.

The business coda is as famous as the chemistry. Cetus awarded Mullis a $10,000 bonus for the idea, and he left the company in 1986. When Cetus's own drug bets later collapsed, its patent estate on the PCR process — not any single medicine — proved the firm's most valuable asset: Britannica records the rights as later sold for $300 million, in a 1992 sale to Switzerland's Hoffmann-La Roche, while Mullis went on to share the 1993 Nobel Prize in chemistry.

Copy DNA by cycling it; copies double forever

Exponential doubling hid in a trivial loop — every existing technique amplified DNA at best linearly, so the cycle itself was the breakthrough.

The recipe needed only primers, a polymerase and heat, so adoption required no capital equipment worth mentioning.

The patents covered a process, not a product, meaning every diagnostic and research lab that ran PCR owed the estate a toll.

When Cetus's drug pipeline failed, the process patents turned out to be the company's most liquid asset.

A method can outvalue a product: process patents tax every downstream use, and that value surfaces when product bets fail. The patent estate is what survives a company's strategy.

Hoffmann-La Roche built PCR into a mainstay of molecular diagnostics, and the method became standard in infection monitoring, forensics and the sequencing era the Nobel committee had pronounced impossible without it. Mullis collected his half of the 1993 chemistry Nobel; the foundational PCR patents eventually expired, leaving the method itself free to everyone.