Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Life in the universe takes orders from space

20.02.2004


A century ago, when biologists used to talk about the primordial soup from which all life on Earth came, they probably never imagined from how far away the ingredients may have come. Recent findings have the origins of life reaching far out from what was once considered "the home planet." Evolution on the early Earth may have been influenced by some pretty far-out stuff.



In a paper published this week in the journal Science, Arizona State University Chemistry Professor Sandra Pizzarello claims that materials from as far away as the interstellar media could possibly have played an active role in establishing the chemistry involved in the origin of life on this planet.

In the paper, Pizarello and her co-author Arthur L. Weber of the SETI Institute show that the exclusive chirality of the proteins and sugars of life on Earth - their tendency to be left- or right-handed, could in fact be due to the chemical contribution of the countless meteorites that struck the planet during its early history. This paper provides a plausible explanation for how, with a little help from outside, the chemistry of non-life - characterized by randomness and complexity - becomes the ordered and specific chemistry of life.


Pizzarello studies meteorites and the chemicals housed within them. A particular type of meteorite - carbonaceous chondrites - holds particular interest. Carbonaceous chondrites are very primitive, stony meteorites that contain organic carbon. These meteorites are rare, but also very exciting for chemists interested in the origins of life on Earth and in the solar system. They contain amino acids - the molecules that make up proteins, and an essential part of the chemistry of life.

According to Pizzarello, it has been known for the last century that there are large amounts of carbon, hydrogen and nitrogen - the so-called biogenic elements - in the cosmos. And that it is reasonable to assume that these elements might have undergone some amount of chemical evolution before life even began.

According to Pizzarello, who studies meteorites from the collection at ASU (which has the largest university-owned collection in the world) the meteorites are the only evidence of chemical evolution scientists have in hand today. New techniques of meteorite analysis are leading to great breakthroughs in understanding where these meteorites came from and how they were formed. Even more exciting, work Pizzarello and her colleagues have recently published in Science explores what sort of contribution the chemical evolution represented by meteorites might have had on the early Earth.

The paper addresses what has been a basic difficulty in relating the chemical evolution represented by meteorites and the origin of terrestrial life on Earth. According to Pizzarello, this problem is that chemical evolution - what we see in meteorites - is characterized by randomness, while terrestrial life relies on specificity and selection. For example, the meteorites contain over 70 amino acids. A mere 20 amino acids make up life’s proteins. "There is a fundamental difficulty in trying to figure out how you go from confusion and randomness to functionality and specificity," said Pizzarello.

So far, only one trait has been found to be similar, to some extent, between amino acids in meteorites and biopolymers, that of L-"handedness" (chirality). Because organic molecules can be asymmetric if they have different groups attached to a carbon atom, they can arrange spatially in two ways, like the two hands, and be either left or right handed. All proteins involved in life on Earth are made up of L-amino acids, while sugars involved in life have a D structure. Scientists call this "homochirality."

An overabundance (excess) of the L-form (the chemical name is enantiomer), has also been found in some amino acids in meteorites. Pizzarello and Weber devised an experiment to find whether or not the amino acids found with L-enantiomeric excess in meteorites could have transferred their asymmetry during organic syntheses on the early Earth . If so, the meteorites could have provided a constant influx of materials with this excess - especially during a period early in the solar system’s history in which the Earth and other planets were pummeled heavily by meteorites.

Pizzarello and Weber report in Science that in fact their experiment succeeded in proving this possibility. In the laboratory, when performing sugar syntheses in water, using reactions that modeled what may have existed on the early Earth, the asymmetry in the amino acids led to a similar asymmetry in the sugars. Pizzarello and Weber thus were able to conclude that the delivery of material from outer space via meteorites - despite the seeming randomness and complexity of these materials - could in fact have "pushed" chemical evolution on Earth toward homochirality.

Pizzarello points out that these findings do not imply that life did not evolve on Earth, or that the meteorites were the only early source of enantiomeric excess - only that the steady contribution of these meteorites might have provided a nudge in the "right" (or, more accurately, "left") direction.

James Hathaway | EurekAlert!
Further information:
http://www.asu.edu/asunews/

More articles from Life Sciences:

nachricht The birth of a new protein
20.10.2017 | University of Arizona

nachricht Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>