Origins of Life and Evolution of Biospheres

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IS EXTRATERRESTRIAL ORGANIC MATTER RELEVANT TO THE ORIGIN OF LIFE ON EARTH?

D. C. B. Whittet

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 249-262

I review the relative importance of internal and external sources of prebiotic molecules on Earth at the time of life's origin μ3.7Gyr ago. The efficiency ofsynthesis in the Earth's atmosphere was critically dependent on its oxidation state. If the early atmosphere was non-reducing and CO2-dominated, external delivery might havebeen the dominant source. Interplanetary dust grains and micrometeorites...

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DETECTION OF ORGANIC MATTER IN INTERSTELLAR GRAINS

Yvonne J. Pendleton

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 53-78

Star formation and the subsequent evolution of planetary systems occurs in dense molecular clouds, which are comprised, in part, of interstellar dust grains gathered from the diffuse interstellar medium (DISM). Radio observations of the interstellar medium reveal the presence of organic molecules in the gas phase and infrared observational studies provide details concerning the solid-state features...

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INTERSTELLAR ICES STUDIED WITH THE INFRARED SPACE OBSERVATORY

D. C. B. Whittet

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 101-113

The Infrared Space Observatory (ISO) was launched by the European Space Agency on 17 November 1995. The availability of spectra from the Short Wavelength Spectrometer (SWS) on ISO is a landmark in the study of interstellar ices and organics; they provide a wealth of data in the 2–20µ region of the spectrum covering the principal solid state resonances of condensed matter in interstellar clouds. We...

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THE EARLY SOLAR SYSTEM

Michael J. Gaffey

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 185-203

Life arose on an early Earth which was the product of the conditions present, and processes operating, during formation of the solar system. The formation and early state of the solar system are reviewed in order to better understand the nature of the early Earth, and to constrain the conditions present during the origin and early evolution of life on this planet.

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ANALOGS OF THE EARLY SOLAR SYSTEM

David W. Koerner

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 157-184

Within the last few decades, the existence of protoplanetary disks has been inferred on the basis of emission from T Tauri stars that does not arise from a stellar photosphere. More recently, high-resolution interferometric techniques have resolved the dust continuum emission, and millimeter arrays have imaged circumstellar molecular gas. These measurements corroborate the disk interpretation; many...

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THE NATURE AND EVOLUTION OF INTERSTELLAR ICES

Jean E. Chiar

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 79-100

The evolution of icy grain mantles is governed by the environment in which they exist. This review presents an overview of the study of the molecules that make up the mantles and discusses their relevance to the origin of life. Models predict two phases of mantle growth during cloud collapse: simple polar and nonpolar molecules dominate the mantle layers at early and late times, respectively (Section...

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CHEMICAL EVOLUTION ON TITAN: COMPARISONS TO THE PREBIOTIC EARTH

David W. Clarke, James P. Ferris

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 225-248

Models for the origin of Titan's atmosphere, the processing of the atmosphere and surface and its exobiological role are reviewed. Titan has gained widespread acceptance in the origin of life field as a model for the types of evolutionary processes that could have occurred on prebiotic Earth. Both Titan and Earth possess significant atmospheres (≥ 1 atm) composed mainly of molecular nitrogen with...

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PHYSICS AND CHEMISTRY OF THE SOLAR NEBULA

Jonathan I. Lunine

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 205-224

The solar system is thought to have begun in a flattened disk of gas and dust referred to traditionally as the solar nebula. Such a construct seems to be a natural product of the collapse of dense parts of giant molecular clouds, the vast star-forming regions that pepper the Milky Way and other galaxies. Gravitational, magnetic and thermal forces within the solar nebula forced a gradual evolution...

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ORIGIN OF THE BIOLOGICALLY IMPORTANT ELEMENTS

Virginia Trimble

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 3-21

The chemical elements most widely distributed in terrestrial living creatures are the ones (apart from inert helium and neon) that are commonest in the Universe — hydrogen, oxygen, carbon, and nitrogen. A chemically different Universe would clearly have different biology, if any. We explore here the nuclear processes in stars, the early Universe, and elsewhere that have produced these common elements,...

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THE SEARCH FOR INTERSTELLAR GLYCINE

Lewis E. Snyder

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 115-133

Millimeter arrays can be used to identify hot young molecular cores which contain large, highly saturated interstellar molecules, including biomolecules. These cores are prime locations for searching for interstellar glycine. The current status of the interstellar glycine search is discussed.

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THE SEARCH FOR LIFE ON MARS

Christopher P. Mckay

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 263-289

Mars appears to have no life on its surface today. However, the presence of fluvial features provides evidence that liquid water was once present on the martian surface. By analogy with Earth, life may have originated on Mars early in its history, possibly during the end of the late heavy bombardment. Analysis of the one meteorite from Mars which dates to this early time appears to contain evidence...

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HABITABLE ZONES AROUND LOW MASS STARS AND THE SEARCH FOR EXTRATERRESTRIAL LIFE

James F. Kasting

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 291-307

Habitable planets are likely to exist around stars nottoo different from the Sun if current theories about terrestrialclimate evolution are correct. Some of these planets may have evolved life, and some of the inhabited planets may have evolved O₂-rich atmospheres. Such atmospheres could be detectedspectroscopically on planets around nearby stars using a space-based interferometer to search for the...

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CIRCUMSTELLAR AND INTERSTELLAR SYNTHESIS OF ORGANIC MOLECULES

A. G. G. M. Tielens, S. B. Charnley

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 23-51

We review the formation and evolution of complex circumstellar and interstellar molecules. A number of promising chemical routes are discussed which may lead to the formation of polycyclic aromatic hydrocarbon molecules, fullerenes, and unsaturated hydrocarbon chains in the outflows from stars. Some of the problems with these chemical schemes are pointed out as well. We also review the role of grains...

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THE ORIGIN OF LOW MASS STARS

B. A. Wilking

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 135-156

Recent evidence indicates that most low mass stars in the Galaxy (<5 Msolar) form alongside massive stars in clusters embedded in giant molecular clouds. Once their parental gas is removed, the fate of these clusters is to disperse and blend into the field population of the galactic disk. The distribution of stellar masses in the solar neighborhood, called the Initial Mass Function, is discussed...

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COMMENTARY

D.C.B. Whittet

Origins of Life and Evolution of Biospheres > 1997 > 27 > 1-3 > 1-1

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VESTIGES OF EARLY MOLECULAR PROCESSES LEADING TO THE GENETIC CODE

Ricardo Ferreira, André Ricardo De O. Cavalcanti

Origins of Life and Evolution of Biospheres > 1997 > 27 > 4 > 397-403

We compare predictions from a proposed model for the origin of the genetic code (J. Theor. Biol (1993) 164, 291–305) with existing information on the base content of codons and abundance of amino acid in different organisms. A comparison is also made between the three groups of amino acids suggested by the model and the two classes of aminoacetyl-tRNA synthetases. The observed agreements tend to suppot...

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FORMALDEHYDE IN HOT SPRINGS

D. E. Ingmanson

Origins of Life and Evolution of Biospheres > 1997 > 27 > 4 > 313-317

Low concentrations (μM) of formaldehyde have been found in four hot springs, two in Iceland, one in Mexico and one in Southern California. A polarographic method for analyzing natural solution for formaldehyde and acetaldehyde is described. A review of other occurrences of formaldehyde in natural solutions is also included.

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EMERGENCE OF TEMPLATE-AND-SEQUENCE-DIRECTED (TSD) SYNTHESES: I. A BIO-GEOCHEMICAL MODEL

Noam Lahav, Shlomo Nir

Origins of Life and Evolution of Biospheres > 1997 > 27 > 4 > 377-395

A biogeochemical model for the evolution of template-and-sequence-directed (TSD) syntheses of biological templates (proto-RNAs) and catalysts (peptides) is described. A fluctuating environment characterized by hydrating (cool) and dehydrating (warm) phases with cycles of consecutive organic reactions, as well as a constant supply of the polymeric building blocks is assumed. The scenario starts with...

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prebiotic transamination

J. Collins Bishop, Stacy D. Cross, Thomas G. Waddell

Origins of Life and Evolution of Biospheres > 1997 > 27 > 4 > 319-324

Biological amino acids and alpha keto acids directly condense with decarboxylation and transamination to yield product amino acids. This process is closely related to unusual amino acid decarboxylase enzymes in certain microorganisms and may represent a primordial mode of amino acid metabolism.

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Modelling of the prebiotic synthesis of oligopeptides: silicate catalysts help to overcome the critical stage

Kirill I. Zamaraev, Vyacheslav N. Romannikov, Rudolph I. Salganik, Wjatschesslaw A. Wlassoff, more

Origins of Life and Evolution of Biospheres > 1997 > 27 > 4 > 325-337

On the basis of experimental studies of the initial stages of glycine oligomerization in aqueous suspension of zeolite and kaolinite catalysts, a model is suggested for the prebiotic synthesis of oligopeptides from α-amino acids. The formation of linear dipeptides by hydrolysis of one amide bond in the cyclic piperazinedione intermediate (formed from glycine spontaneously) is found to be the critical...

INFONA - science communication portal

Origins of Life and Evolution of Biospheres

IS EXTRATERRESTRIAL ORGANIC MATTER RELEVANT TO THE ORIGIN OF LIFE ON EARTH?

DETECTION OF ORGANIC MATTER IN INTERSTELLAR GRAINS

INTERSTELLAR ICES STUDIED WITH THE INFRARED SPACE OBSERVATORY

THE EARLY SOLAR SYSTEM

ANALOGS OF THE EARLY SOLAR SYSTEM

THE NATURE AND EVOLUTION OF INTERSTELLAR ICES

CHEMICAL EVOLUTION ON TITAN: COMPARISONS TO THE PREBIOTIC EARTH

PHYSICS AND CHEMISTRY OF THE SOLAR NEBULA

ORIGIN OF THE BIOLOGICALLY IMPORTANT ELEMENTS

THE SEARCH FOR INTERSTELLAR GLYCINE

THE SEARCH FOR LIFE ON MARS

HABITABLE ZONES AROUND LOW MASS STARS AND THE SEARCH FOR EXTRATERRESTRIAL LIFE

CIRCUMSTELLAR AND INTERSTELLAR SYNTHESIS OF ORGANIC MOLECULES

THE ORIGIN OF LOW MASS STARS

COMMENTARY

VESTIGES OF EARLY MOLECULAR PROCESSES LEADING TO THE GENETIC CODE

FORMALDEHYDE IN HOT SPRINGS

EMERGENCE OF TEMPLATE-AND-SEQUENCE-DIRECTED (TSD) SYNTHESES: I. A BIO-GEOCHEMICAL MODEL

prebiotic transamination

Modelling of the prebiotic synthesis of oligopeptides: silicate catalysts help to overcome the critical stage

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