NEW YORK — Roger Y. Tsien, who won a Nobel Prize in chemistry for creating a rainbow of fluorescent proteins that could light up the dance of molecules within cells, died Aug. 24 in Eugene, Ore, according to the University of California San Diego, where he was a professor of chemistry and biochemistry. He was 64.

A university spokesman said he did not have information about the cause, but Mr. Tsien, who was visiting Eugene, had suffered a “medical event’’ while bicycling.

Although other scientists made the initial discoveries of a green fluorescent protein from jellyfish, Mr. Tsien transformed it into the ubiquitous tool used by biologists today.

After another scientist, Douglas C. Prasher, provided a copy of the gene that encodes the protein, Mr. Tsien set out to make a better version.

“Roger, in his brilliant ingenuity, figured it should be possible to play with it,’’ Charles S. Zuker, a former colleague who is now at Columbia, said in an interview. “He would do the simplest, most clever experiments to get at some of the most fundamental questions in contemporary biology.’’

The original protein glowed green when ultraviolet or blue light was shined on it. Mr. Tsien and the other members of his laboratory mutated the gene so that the proteins glowed brighter under blue light, which made them easier for biologists to use. (Ultraviolet light damages living cells.)

When biologists seek to track the comings and goings of a particular protein in a cell, they first identify the gene that produces it. Then they splice the genetic instructions for the green fluorescent protein into the gene. The result is that the protein they want to track is tagged with a fluorescent snippet, a beacon easily visible under a microscope.

Mr. Tsien’s laboratory then created a version that glowed blue instead of green. Other colors followed. That enabled the tracking of multiple molecules inside living cells.

“It created a new universe of biology,’’ Zuker said.

In 2008, Mr. Tsien shared the chemistry Nobel with Osamu Shimomura of the Marine Biological Laboratory in Woods Hole and Boston University School of Medicine, who discovered the jellyfish protein, and Martin Chalfie, a professor of biological sciences at Columbia, the first to insert the green fluorescent protein gene into another organism.

A native of New York City, Roger Yonchien Tsien recalled that his parents bought him a chemistry set when he was in elementary school, but he “didn’t find it very interesting because the experiments seemed so tame.’’

He entered Harvard at 16 and graduated with a degree in chemistry and physics in 1972. He earned a doctorate in physiology from the University of Cambridge in England in 1977.