STOCKHOLM, Sweden — American Roger Kornberg, whose father won a Nobel Prize a half-century ago, was awarded the prize in chemistry today for his studies of how cells take information from genes to produce proteins.

The work is important for medicine, because disturbances in that process are involved in illnesses like cancer, heart disease and various kinds of inflammation. And learning more about the process is key to using stem cells to treat disease.

Kornberg, 59, a professor at the Stanford University School of Medicine, had just spent two days traveling from Europe to his home in California when he learned of the honor.

"When the telephone first rang I was completely bewildered," he said in a telephone interview with journalists in the Swedish capital. "I'm still shaking. I hope I will be able to calm down shortly."

Kornberg's father, Arthur, shared the 1959 Nobel medicine prize with Severo Ochoa for studies of how genetic information is transferred from one DNA molecule to another.

The younger Kornberg said he remembered traveling to Stockholm with his father for the Nobel Prize ceremonies.

"I have always been an admirer of his work and that of many others preceding me. I view them as truly giants of the last 50 years."

Since 2000, Kornberg has produced actual pictures of messenger RNA molecules being created, a process that resembles building a chain link by link.