Subscribe free to our newsletters via your
. 24/7 Space News .




EXO LIFE
Did Metabolism Come First In Evolution
by Staff Writers
Barcelona, Spain (SPX) Jan 11, 2010


In the first half of the 20th century, Alexander Oparin established the "Metabolism First" hypothesis to explain the origin of life, thus strengthening the primary role of cells as small drops of coacervates (evolutionary precursors of the first prokaryote cells). Dr Oparin did not refer to RNA or DNA molecules since at that time it was not clear just how important the role of these molecules was in living organisms. However he did form a solid base for the idea of self-replication as a collective property of molecular compounds.

A research published in Proceedings of National Academy of Sciences rejects the theory that the origin of life stems from a system of self-catalytic molecules capable of experiencing Darwinian evolution without the need of RNA or DNA and their replication.

The research, which was carried out with the participation of Mauro Santos, researcher of the Department of Genetics and Microbiology at Universitat Autonoma de Barcelona (UAB), has demonstrated that, through the analysis of what some researchers name "compound genomes", these chemical networks cannot be considered evolutionary units because they lose properties which are essential for evolution when they reach a critical size and greater level of complexity.

The US space agency NASA defines life as a "self-sustaining chemical system capable of Darwinian evolution". The scientific theories on the origin of life revolve around two main ideas: one focuses on genetics - with RNA or DNA replication as an essential condition for Darwinian evolution to take place - and the other focuses on metabolism.

It is clear that both situations must have begun with simple organic molecules formed by prebiotic processes, as was demonstrated by the Miller-Urey experiment (in which organic molecules were created from inorganic substances). The point in which these two theories differ is that the replication of RNA or DNA molecules is a far too complex process which requires a correct combination of monomers within the polymers to produce a molecular chain resulting from the replication.

Until now no plausible chemical explanation exists for how these processes occured. In addition, defenders of the second theory argue that the processes needed for evolution to take place depend on primordial metabolism.

This metabolism is believed to be a type of chemical network entailing a high degree of mutual catalysis between its components which, in turn, eventually allows for adaptation and evolution without any molecular replication.

In the first half of the 20th century, Alexander Oparin established the "Metabolism First" hypothesis to explain the origin of life, thus strengthening the primary role of cells as small drops of coacervates (evolutionary precursors of the first prokaryote cells).

Dr Oparin did not refer to RNA or DNA molecules since at that time it was not clear just how important the role of these molecules was in living organisms. However he did form a solid base for the idea of self-replication as a collective property of molecular compounds.

Science more recently demonstrated that sets of chemical components store information about their composition which can be duplicated and transmitted to their descendents.

This has led to their being named "compound genomes" or composomes. In other words, heredity does not require information in order to be stored in RNA or DNA molecules. These "compound genomes" apparently fulfil the conditions required to be considered evolutionary units, which suggests a pathway from pre-Darwinian dynamics to a minimum protocell.

Researchers in this study nevertheless reveal that these systems are incapable of undergoing a Darwinian evolution. For the first time a rigorous analysis was carried out to study the supposed evolution of these molecular networks using a combination of numerical and analytical simulations and network analysis approximations.

Their research demonstrated that the dynamics of molecular compound populations which divide after having reached a critical size do not evolve, since during this process the compounds lose properties which are essential for Darwinian evolution.

Researchers concluded that this fundamental limitation of "compound genomes" should lead to caution towards theories that set metabolism first as the origin as life, even though former metabolic systems could have offered a stable habitat in which primitive polymers such as RNA could have evolved.

Researchers state that different prebiotic Earth scenarios can be considered. However, the basic property of life as a system capable of undergoing Darwinian evolution began when genetic information was finally stored and transmitted such as occurs in nucleotide polymers (RNA and DNA).

.


Related Links
Universitat Autonoma de Barcelona
Life Beyond Earth
Lands Beyond Beyond - extra solar planets - news and science






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EXO LIFE
Lifeless Prions Capable Of Evolutionary Change And Adaptation
Jupiter FL (SPX) Jan 04, 2010
Scientists from The Scripps Research Institute have determined for the first time that prions, bits of infectious protein devoid of DNA or RNA that can cause fatal neurodegenerative disease, are capable of Darwinian evolution. The study from Scripps Florida in Jupiter shows that prions can develop large numbers of mutations at the protein level and, through natural selection, these mutatio ... read more


EXO LIFE
Planning Our Phases On The Moon

Space Systems Loral To Supply Lunar Mission Propulsion System

Lava tube could house moon colony

Moon Mission In Running For Next Big Space Venture

EXO LIFE
Spirit Tries A Toe-In Maneuver

Opportunity Examinines 'Marquette Island's' Interior

Minimal Progress In Recent Extraction Drives

Goddard Scientist Breakthrough Given Ticket To Mars

EXO LIFE
Spectacular Years Ahead In Space

Galactic GPS Possible With Pulsars And Gravity Waves

US still has space ambitions: NASA chief

Chairman Gordon Comments On President's Budget Request

EXO LIFE
China Building Large Radio Telescope For Space Observation

China To Launch Civil HD Survey Satellite In 2011

China Launches First Public-Welfare Mini Satellite

Chang'e-1 Has Blazed A New Trail In China's Deep Space Exploration

EXO LIFE
How To Live Long And Prosper In Space

Russia Set To Launch Another Space Truck To ISS

Obama budget extends US commitment to space station

Mini-Research Module MRM1 At Cape For Shuttle Processing

EXO LIFE
USAF Awards ULA WGS-4 Satellite Launch

ISRO Plans Special Launch Pad At Sriharikotta

Arianespace Poised For 2010 Boost

Booz Allen Hamilton To Transform LA Spacelift Range

EXO LIFE
Second Smallest Exoplanet Found To Date Discovered At Keck

Massive Stars Easy Targets For Planet Hunters

Most Earth-Like Exoplanet Started Out As A Gas Giant

Sun Glints Seen From Space Signal Oceans And Lakes

EXO LIFE
New sunglasses can also be used for 3-D viewing

Plastic Logic aims QUE e-reader at business crowd

XMM-Newton Sensors Celebrate A Decade Of Discovery

3-D TV a rage at Consumer Electronics Show




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement