Scientists Reproduce a Building Block of Life in Laboratory

Nov 06, 2009
The molecular structures of pyrimidine and uracil.

(PhysOrg.com) -- NASA scientists studying the origin of life have reproduced uracil, a key component of our hereditary material, in the laboratory.

NASA scientists studying the have reproduced uracil, a key component of our hereditary material, in the laboratory. They discovered that an ice sample containing pyrimidine exposed to under space-like conditions produces this essential ingredient of life.

Pyrimidine is a ring-shaped molecule made up of carbon and nitrogen and is the basic structure for uracil, part of a genetic code found in (RNA). RNA is central to protein synthesis, but has many other roles.

"We have demonstrated for the first time that we can make uracil, a component of RNA, non-biologically in a laboratory under conditions found in space," said Michel Nuevo, research scientist at NASA's Ames Research Center, Moffett Field, Calif. "We are showing that these laboratory processes, which simulate occurrences in outer space, can make a fundamental building block used by on Earth."

Nuevo is the lead author of a research paper titled “Formation of Uracil from the Ultraviolet Photo-Irradiation of Pyrimidine in Pure Water Ices,” Astrobiology vol. 9 no. 7, published Oct. 1, 2009.

NASA Ames scientists have been simulating the environments found in and the outer for years. During this time, they have studied a class of carbon-rich compounds, called polycyclic (PAHs), which have been identified in meteorites, and are the most common carbon-rich compound observed in the universe. PAHs typically are six-carbon ringed structures that resemble fused hexagons, or a piece of chicken wire.

Pyrimidine also is found in meteorites, although scientists still do not know its origin. It may be similar to the carbon-rich PAHs, in that it may be produced in the final outbursts of dying, giant red stars, or formed in dense clouds of interstellar gas and dust.

“Molecules like pyrimidine have nitrogen atoms in their ring structures, which makes them somewhat whimpy. As a less stable molecule, it is more susceptible to destruction by radiation, compared to its counterparts that don’t have nitrogen,” said Scott Sandford, a space science researcher at Ames. “We wanted to test whether pyrimidine can survive in space, and whether it can undergo reactions that turn it into more complicated organic species, such as the nucleobase uracil.”

Stefanie Milam, Michel Nuevo and Scott Sandford. Photo credit: Dominic Hart/NASA

In theory, the researchers thought that if molecules of pyrimidine could survive long enough to migrate into interstellar dust clouds, they might be able to shield themselves from radiation destruction. Once in the clouds, most molecules freeze onto dust grains (much like moisture in your breath condenses on a cold window during winter).

These clouds are dense enough to screen out much of the surrounding outside radiation of space, thereby providing some protection to the molecules inside the clouds.

Scientists tested their hypotheses in the Ames Astrochemistry Laboratory. During their experiment, they exposed the ice sample containing pyrimidine to ultraviolet radiation under space-like conditions, including a very high vacuum, extremely low temperatures (approximately - 340 degrees Fahrenheit), and harsh radiation.

They found that when pyrimidine is frozen in water ice, it is much less vulnerable to destruction by radiation. Instead of being destroyed, many of the molecules took on new forms, such as the RNA component uracil, which is found in the genetic make-up of all living organisms on Earth.

“We are trying to address the mechanisms in space that are forming these molecules. Considering what we produced in the laboratory, the chemistry of ice exposed to ultraviolet radiation may be an important linking step between what goes on in space and what fell to Earth early in its development,” said Stefanie Milam, a researcher at NASA Ames and a co-author of the research paper.

“Nobody really understands how life got started on Earth. Our experiments demonstrate that once the Earth formed, many of the building blocks of life were likely present from the beginning. Since we are simulating universal astrophysical conditions, the same is likely wherever planets are formed,” explained Sandford.

Provided by JPL/NASA (news : web)

Explore further: Four billion-year-old chemistry in cells today

add to favorites email to friend print save as pdf

Related Stories

Life's Building Blocks Are Common In Space

Oct 11, 2005

A team of NASA exobiology researchers revealed today organic chemicals that play a crucial role in the chemistry of life are common in space. "Our work shows a class of compounds that is critical to biochemistry is ...

Researcher Presents Origin-Of-Life Theory for Young Earth

Aug 14, 2007

Some of the elements necessary to support life on Earth are widely known - oxygen, carbon and water, to name a few. Just as important in the existence of life as any other component is the presence of adenine, an essential ...

Building Life From Star-Stuff

Sep 08, 2005

Life on Earth was made possible by the death of stars. Atoms like carbon and oxygen were expelled in the last few dying gasps of stars after their final supplies of hydrogen fuel were used up.

Clues to our birth may be written in space

Jan 22, 2005

Extraterrestrial molecules found in meteorites may hold the key to the origin of life on Earth, according to chemistry research at the University of Leeds. Dr Terence Kee and a team from Leeds and Bradford universities are ...

Spitzer's Eyes Perfect for Spotting Diamonds in the Sky

Feb 26, 2008

Diamonds may be rare on Earth, but surprisingly common in space -- and the super-sensitive infrared eyes of NASA's Spitzer Space Telescope are perfect for scouting them, say scientists at the NASA Ames Research ...

Recommended for you

A new approach to creating organic zeolites

Jul 24, 2014

Yushan Yan, Distinguished Professor of Engineering at the University of Delaware, is known worldwide for using nanomaterials to solve problems in energy engineering, environmental sustainability and electronics.

User comments : 0