Building Blocks of Life Found in Two Meteorites

Bijal P. Trivedi
National Geographic Today
December 19, 2001

During a recent analysis of two meteorites scientists got a sweet surprise; they detected the presence of a sugar and many sugar-related compounds.

The sugar and sugar-like molecules, collectively called polyols, were found in the Murchison meteorite that fell in Murchison, Australia, in 1969 and the Murray meteor that fell in Kentucky in 1950—two meteorites that are rich in carbon.

Sugars play an essential role in living organisms. They are a component of both types of genetic material—RNA and DNA—they provide a source of energy, and they form an essential structural component of the membrane that surrounds every cell.

Previous studies have revealed that the meteorites also contain amino acids, which are the building blocks of proteins, and present in all life forms.

Some scientists have speculated that material from meteors may have provided some starting material for early life forms, possibly even jump-starting the origin of life itself.

The research is published in the December 20 issue of the journal Nature.

"We may never know what particular compounds were important for the very start of life, we weren't there to observe," says George Cooper, of NASA Ames Research Center in Mofett Field, California, who led the research.

The finding is important because it proves that two classes of biologically important compounds—sugars and amino acids—may have had extraterrestrial origins. These meteors were thought to be formed about 4.5 billion years ago—fairly early in the life of the solar system.

A commentary that accompanies Cooper's report suggests that starlight may have acted upon icy mixtures of water, ammonia, and carbon monoxide to form simple sugars such as those found on the Murchison meteorite.

Issues of contamination have muddied investigations to detect these substances from previous meteorite samples.

To address concerns that the polyols were not contaminants from Earth, Cooper and colleagues measured the quantities of these compounds and their atomic makeup.

The researchers found that the sugar-related compounds contain more heavy isotopes of both hydrogen and carbon than would be found if the compounds were formed on Earth through biological processes.

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