Genetics and Health

Key to “life” before its origin on earth

by Elaine on March 2nd, 2008

All amino acids are “left handed” (Image courtesy of www.answersingenesis.com) 

Scientists have long known that most compounds in living things exist in mirror-image forms. The two forms are like hands; one is a mirror reflection of the other. They are different, cannot be superimposed, yet identical in their parts.

When scientists synthesize these molecules in the laboratory, half of a sample turns out to be “left-handed” and the other half “right-handed.” But amino acids, which are the building blocks of terrestrial proteins, are all “left-handed,” while the sugars of DNA and RNA are “right-handed”.

Years ago Arizona State University’s Sandra Pizzarello and professor emeritus John Cronin analyzed amino acids from the Murchison meteorite (which landed in Australia in 1969) that were unknown on Earth, hence solving the problem of any contamination. They discovered a preponderance of “left-handed” amino acids over their “right-handed” form.

Murchison meteorite

Pizzarello then worked in studying the organic materials of a special group of meteorites that contain among a variety of compounds, amino acids that have identical counterparts in terrestrial biomolecules. These meteorites are fragments of asteroids that are about the same age as the solar system (roughly 4.5 billion years.) one of which was found in Antarctica and an exceptionally pristine meteorite. Antarctic ices are good “curators” of meteorites. After a meteorite falls - and meteorites have been falling throughout the history of Earth - it is quickly covered by snow and buried in the ice. Because these ices are in constant motion, when they come to a mountain, they will flow over the hill and bring meteorites to the surface.

Thanks to the pristine nature of this meteorite, Pizzarello and the team were able to demonstrate that some of the possible abiotic precursors to the origin of life on Earth have been shown to carry “handedness” in a larger number than previously thought.

Elaine Warburton  www.geneticsandhealth.com

Share This

Related Stories

Ethics of Genetics Conference in Calgary, Canada
Earth Day - Mother Nature is waiting ….
Titan - Earth’s twin is of interest to new life-hunters
Celebrate 150 years of Charles Darwin’s evolutionary theory
‘Junk DNA’ may hold key to the evolution of complex organisms

POSTED IN: Amino acids, Evolution, General Genetics and Health, Origin of life