General discussion after session V

1988 ◽  
Vol 325 (1587) ◽  
pp. 611-618 ◽  
Keyword(s):  
Origin Of Life ◽  
Time Perspective ◽  
Applied Mathematics ◽  
Building Blocks ◽  
Living Systems ◽  
Organic Chemical ◽  
General Terms ◽  
The Earth ◽  
The Origin Of Life ◽  
Emergence Of Life

N. C. Wickramasinghe ( Department of Applied Mathematics and Astronomy, University College, Cardiff, U. K. ). The question of the origin of life is, of course, one of the most important scientific questions and it is also one of the most difficult. One is inevitably faced here with a situation where there are very few empirical facts of direct relevance and perhaps no facts relating to the actual transition from organic material to material that can even remotely be described as living. The time perspective of events that relate to this problem has already been presented by Dr Chang. Uncertainty still persists as to the actual first moment of the origin or the emergence of life on the Earth. At some time between 3800 and 3300 Ma BP the first microscopic living systems seem to have emerged. There is a definite moment in time corresponding to a sudden appearance of cellular-type living systems. Now, traditionally the evolution of carbonaceous compounds which led to the emergence of life on Earth could be divided into three principal steps and I shall just remind you what those steps are. The first step is the production of chemical building blocks that lead to the origin of the organic molecules necessary as a prerequisite for the evolution of life. Step two can be described in general terms as prebiotic evolution, the arrangement of these chemical units into some kind of sequence of precursor systems that come almost up to life but not quite; and then stage three is the early biological evolution which actually effects the transition from proto-cellular organic-type forms into truly cellular living systems. The transition is from organic chemistry, prebiotic chemistry to biochemistry. Those are the three principal stages that have been defined by traditional workers in the field, the people who, as Dr Chang said, have had the courage to make these queries and attempt to answer them. Ever since the classic experiments where organic materials were synthesized in the laboratory a few decades back, it was thought that the first step, the production of organic chemical units, is important for the origin of life on the Earth, and that this had to take place in some location on the Earth itself.

scholarly journals Geochemistry and the Origin of Life: From Extraterrestrial Processes, Chemical Evolution on Earth, Fossilized Life’s Records, to Natures of the Extant Life

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 39 ◽  
Author(s):  
Satoru Nakashima ◽  
Yoko Kebukawa ◽  
Norio Kitadai ◽  
Motoko Igisu ◽  
Natsuki Matsuoka
Keyword(s):  
Origin Of Life ◽  
Chemical Evolution ◽  
Building Blocks ◽  
Spectroscopic Studies ◽  
Research Progress ◽  
Complex Nature ◽  
Water Molecules ◽  
Evolution Of Life ◽  
The Origin Of Life ◽  
Emergence Of Life

In 2001, the first author (S.N.) led the publication of a book entitled “Geochemistry and the origin of life” in collaboration with Dr. Andre Brack aiming to figure out geo- and astro-chemical processes essential for the emergence of life. Since then, a great number of research progress has been achieved in the relevant topics from our group and others, ranging from the extraterrestrial inputs of life’s building blocks, the chemical evolution on Earth with the aid of mineral catalysts, to the fossilized records of ancient microorganisms. Here, in addition to summarizing these findings for the origin and early evolution of life, we propose a new hypothesis for the generation and co-evolution of photosynthesis with the redox and photochemical conditions on the Earth’s surface. Besides these bottom-up approaches, we introduce an experimental study on the role of water molecules in the life’s function, focusing on the transition from live, dormant, and dead states through dehydration/hydration. Further spectroscopic studies on the hydrogen bonding behaviors of water molecules in living cells will provide important clues to solve the complex nature of life.

scholarly journals Astrobiology: Towards an Understanding of the Emergence of Life in the Universe

2004 ◽  
Vol 213 ◽  
pp. 245-254 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Evolutionary Biology ◽  
Living Systems ◽  
Spontaneous Generation ◽  
Terrestrial Environment ◽  
Random Events ◽  
The Origin Of Life ◽  
Emergence Of Life ◽  
Considerable Detail ◽  
The Universe

Long before the idea of spontaneous generation was incorporated by JeanBaptiste de Lamarck into evolutionary biology to explain the first emergence of life, the possibility that other planets were inhabited had been discussed, sometimes in considerable detail, by scientists and philosophers alike (Lazcano 2001). More often than not, these were speculations that rested on the idea of a uniform universe but with little or no empirical basis. Today our approaches to the issue of life in the Universe have changed dramatically; neither the formation of planets nor the origin of life are seen as the result of inscrutable random events, but rather as natural outcomes of evolutionary events. The interconnection between these two processes is evident: understanding the formation of planets has major implications for our understanding of the early terrestrial environment, and therefore for the origin of living systems.

scholarly journals The chemical origins of life and its early evolution: an introduction

2011 ◽  
Vol 366 (1580) ◽  
pp. 2853-2856 ◽  
Author(s):  
David M. J. Lilley ◽  
John Sutherland
Keyword(s):  
Nucleic Acids ◽  
Origin Of Life ◽  
Chemical Reactions ◽  
Rna World ◽  
Building Blocks ◽  
Transferase Activity ◽  
Peptidyl Transferase ◽  
Self Assembling ◽  
The Earth ◽  
The Origin Of Life

Can we look at contemporary biology and couple this with chemical insight to propose some plausible mechanisms for the origin of life on the planet? In what follows, we examine some promising chemical reactions by which the building blocks for nucleic acids might have been created about a billion years after the Earth formed. This could have led to self-assembling systems that were based on an all-RNA metabolism, where RNA is both catalytic and informational. We consider the breadth of RNA enzymes presently existing in biology, and to what extent these might have covered a wider range of chemistry in the RNA world. Ultimately, the RNA world would probably have given way to protein-based life quite quickly, and the origins of peptidyl transferase activity are discussed below.

Photochemical Evolution of Interstellar/Precometary Organic Material

1997 ◽  
Vol 161 ◽  
pp. 23-47 ◽  
Author(s):  
Louis J. Allamandola ◽  
Max P. Bernstein ◽  
Scott A. Sandford
Keyword(s):  
Origin Of Life ◽  
Building Blocks ◽  
Complex Species ◽  
Infrared Observations ◽  
Interstellar Ice ◽  
Polycyclic Aromatic ◽  
Ultraviolet Photolysis ◽  
The Origin Of Life ◽  
Simple Molecules ◽  
Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

How Did It All Begin?: The Self-Assembly of Organic Molecules and the Origin of Cellular Life

2002 ◽  
Vol 11 ◽  
pp. 179-194
Author(s):  
David W. Deamer
Keyword(s):  
Origin Of Life ◽  
20Th Century ◽  
Self Assembly ◽  
Organic Molecules ◽  
Western Culture ◽  
The Self ◽  
Late 20Th Century ◽  
Cellular Life ◽  
The Earth ◽  
The Origin Of Life

Movies are the myths of late-20th century western culture. Because of the power of films likeETto capture our imagination, we are more likely than past generations to accept the possibility that life exists elsewhere in our galaxy. Such a myth can be used to sketch the main themes of this chapter, which concern the origin of life on the Earth.

The sulfocyanic theory on the origin of life: towards a critical reappraisal of an autotrophic theory

2003 ◽  
Vol 2 (4) ◽  
pp. 301-306 ◽  
Author(s):  
L. Perezgasga ◽  
E. Silva ◽  
A. Lazcano ◽  
A. Negrón-Mendoza
Keyword(s):  
Amino Acids ◽  
Origin Of Life ◽  
Raw Materials ◽  
Total Yield ◽  
Historical Analysis ◽  
Preliminary Identification ◽  
Chemical Significance ◽  
The Origin Of Life ◽  
Materials Used ◽  
Emergence Of Life

In the early 1930s, Alfonso L. Herrera proposed his so-called sulfocyanic theory on the origin of life, an autotrophic proposal on the first living beings according to which NH4SCN and H2CO acted as raw materials for the synthesis of bio-organic compounds inside primordial photosynthetic protoplasmic structures. Although the work of Herrera is frequently cited in historical analysis of the development of the origin of life studies, very little attention has been given to the chemical significance of the reactions he published. In this paper we report the results of our search for amino acids obtained from a reactive mixture used by Herrera from 1933 onwards. Chromatograms using the high-pressure liquid chromatography (HPLC) technique suggest the presence of several amino acids, the total yield being 2% of the initial thiocyanate used. Preliminary identification based on HPLC retention times suggests the presence of glycine, alanine, cysteine and methionine. Alanine was the most abundant amino acid in all samples of fractionated material analysed. Although the starting materials used by Herrera were determined by his autotrophic hypothesis on the origin of cells, our results show that his experiments may provide insights into the abiotic synthesis of sulfur-containing amino acids within the framework of a heterotrophic emergence of life.

scholarly journals An optimal degree of physical and chemical heterogeneity for the origin of life?

2011 ◽  
Vol 366 (1580) ◽  
pp. 2894-2901 ◽  
Author(s):  
Jack W. Szostak
Keyword(s):  
Nucleic Acid ◽  
Origin Of Life ◽  
Self Assembly ◽  
Building Blocks ◽  
Reaction Products ◽  
Amphiphilic Molecules ◽  
Essential Components ◽  
The Origin Of Life ◽  
Chemical Inputs ◽  
Physical And Chemical

The accumulation of pure, concentrated chemical building blocks, from which the essential components of protocells could be assembled, has long been viewed as a necessary, but extremely difficult step on the pathway to the origin of life. However, recent experiments have shown that moderately increasing the complexity of a set of chemical inputs can in some cases lead to a dramatic simplification of the resulting reaction products. Similarly, model protocell membranes composed of certain mixtures of amphiphilic molecules have superior physical properties than membranes composed of single amphiphiles. Moreover, membrane self-assembly under simple and natural conditions gives rise to heterogeneous mixtures of large multi-lamellar vesicles, which are predisposed to a robust pathway of growth and division that simpler and more homogeneous small unilamellar vesicles cannot undergo. Might a similar relaxation of the constraints on building block purity and homogeneity actually facilitate the difficult process of nucleic acid replication? Several arguments suggest that mixtures of monomers and short oligonucleotides may enable the chemical copying of polynucleotides of sufficient length and sequence complexity to allow for the emergence of the first nucleic acid catalysts. The question of the origin of life may become less daunting once the constraints of overly well-defined laboratory experiments are appropriately relaxed.

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