Americans Venkatraman Ramakrishnan and Thomas Steitz and Israeli Ada Yonath won the 2009 Nobel Prize in chemistry on Wednesday for mapping ribosomes, the protein-producing factories within cells, at the atomic level.

The Royal Swedish Academy of Sciences said their work has been fundamental to the scientific understanding of life and has helped researchers develop antibiotic cures for various diseases.

Yonath is the fourth woman to win the Nobel chemistry prize and the first since 1964, when Dorothy Crowfoot Hodgkin of Britain received the prize.

This year's three laureates all generated three-dimensional models that show how different antibiotics bind to ribosomes.

"These models are now used by scientists in order to develop new antibiotics, directly assisting the saving of lives and decreasing humanity's suffering," the academy said in its announcement.

"All three have used a method called X-ray crystallography to map the position for each and every one of the hundreds of thousands of atoms that make up the ribosome," the academy said.

Alfred Nobel, a Swedish industrialist who invented dynamite, established the Nobel Prizes in his will in 1895. The first awards were handed out six years later.

Each prize comes with a 10 million kronor ($1.4 million) purse, a diploma, a gold medal and an invitation to the prize ceremony in Stockholm on Dec. 10. The Peace Prize is handed out in Oslo.

On Monday, three American scientists shared the Nobel Prize in medicine for discovering a key mechanism in the genetic operations of cells, an insight that has inspired new lines of research into cancer.

The physics prize on Tuesday was split between a Hong Kong-based scientist who helped develop fiber-optic cable and two Canadian and American researchers who invented the "eye" in digital cameras — technology that has revolutionized communications and science.

The literature and peace prize winners will be announced later this week and the economics announcement is set for Monday.