On the origin of life event

On the assumption of a uniform sample space probability hypothesis it is estimated a maximum number of polypeptides (or other kind of polymers) that could be synthesized in the prebiotic Earth. Besides, on the basis of five premises that are postulated as indispensable requirements for the origin of a living system, under the constraints of a protein-nucleic acid chemistry, it is concluded categorically that the origin of life event could not be the result of unbiased polymerization phenomena. On the contrary, biased and specific patterns of polymerization had to be an essential component in this fundamental event.Finally, several theories on the origin of life and complementary concepts like hypercyclic organization and self-organization phenomena in dissipative structures are discussed in the light of the conclusions arrived at in this work.     

After the origin of life

Acta Biotheoretica - As to the primary morphogenesis which occurred after the origin of life, two conditions are considered. The above conditions are satisfied by the morphogenetic polarity....     

Macromolecules and the origin of life

From our knonwledge of present day organisms, it is hard to imagine a living assembly, even at its most primitive stage, without macromolecules.In order to look for the macromolecules which possibly participated in the assembly of the primitive organisms, the reaction and formation of polymers in HCN under irradiation of ultraviolet ray of 184.9 nm. was studied.As a example of a simple way of producing an assembly of macromolecules, the mechanism of coacervation was studied by using gelatin as the material.     

Self-organization at the origin of life

The concept of an (M,R) system with organizational invariance allows one to understand how a system may be able to maintain itself indefinitely if it is coupled to an external source of energy and materials. However, although this constitutes an important step towards understanding the difference between a living and a non-living system, it is not clear that an (M,R) system with organizational invariance is sufficient to define a living system. To take a further step towards defining what it means to be alive it is necessary to add to a simple (M,R) system some property that represents its identity, and which can be maintained and modified in subsequent generations.     

Chance and the origin of life

Random chemical reactions in the Earth's primitive hydrosphere could have generated no more than 200 bits of information, whereas the first Darwinian organism must have encoded about a million bits, and therefore could not have arisen by chance. This information gap is bridged by separating reproduction from organism, and postulating a reproductive chemical community that would generate information by proto-Darwinian evolution. The information content of the initial community could have been as low as 160 bits, and its evolution might have led to the first Darwinian cell.     

Symbiosis and the origin of life

The paper uses chemical kinetic arguments and illustrations by computer modelling to discuss the origin and evolution of life. Complex self-reproducing chemical systems cannot arise spontaneously, whereas simple auto-catalytic systems can, especially in an irradiated aqueous medium. Self-reproducing chemical particles of any complexity, in an appropriate environment, have a self-regulating property which permits long-term survival. However, loss of materials from the environment can lead to continuing decay which is circumvented by physical union between different kinds of self-reproducing particles. The increasing complexity produced by such unions (symbioses) is irreversible so that the chemical system evolves. It is suggested that evolution by successive symbioses brough about the change from simple, spontaneously arising, auto-catalytic particles to complex prokaryotic cells.     

Chance and the origin of life

Random chemical reactions in the Earth's primitive hydrosphere could have generated no more than 200 bits of information, whereas the first Darwinian organism must have encoded about a million bits, and therefore could not have arisen by chance. This information gap is bridged by separating reproduction from organism, and postulating a reproductive chemical community that would generate information by proto-Darwinian evolution. The information content of the initial comunity could have been as low as 160 bits, and its evolution might have led to the first Darwinian cell.     

Clay and the origin of life

Research concerning the possible role of clay in chemical evolution is reviewed. The probable importance of clays in the origin of life is assessed.     

Parasites at the origin of life

This paper is concerned with parasitic virus-like particles and their hosts. It is proposed that parasitism must have occurred at an early stage of evolution, soon after the first self-reproducing systems had formed. When chemical building blocks for self-reproducing systems became scarce, current theories envision that some self-reproducing systems evolved the capability to synthesize materials for self-replication from chemical precursors in the environment. It is proposed that at about the same time parasitic systems (phages) arose that replicated at the expense of host systems by diverting host materials to the replication of their own genomes. With the aid of a mathematical model we demonstrate that host and phages can coexist in a stable equilibrium, depending upon the carrying capacity of the environment. If the latter falls below a threshold, then the parasites die out. A parasite that has the capability to integrate into the host genome is replicated along with it and thus escapes extinction during periods of population bottlenecks of the host population. The presence of phages creates evolutionary pressures favoring host defenses against them. Thus, modern bacteria are able to degrade most invading DNA (through restriction enzymes). Defense capabilities require a share of the genome, thus adding to the genetic complexity of organisms.     

A theory of the origin of life

Life on Earth is essentially nucleic acids (NAs) influencing peptide synthesis such that NA replication is favored. It is proposed that the ability to synthesize polypeptides evolved gradually — one peptide bond at a time. The proposed evolution of the peptide synthesis apparatus begins with a transfer NA (tNA) which catalyzes the transfer of activated amino acids to accessible amino groups in its environment. The resulting capped molecules (with single amino acid caps) in turn favor NA replication. The proposed evolution of the peptide synthesis apparatus from the tNA onward is characterized by a progressive increase in the number of amino acids per cap: two tNAs jointly produce a dipeptide cap, three tNAs jointly produce a tripeptide cap, etc. Messenger NAs evolve because they can specify the composition and sequence order of the peptide caps. Lastly, ribosomal NAs evolve. The origin, expansion, and standardization of the genetic code are discussed. It is proposed that the present triplet code evolved by a process of codon length refinement, and that originally codons of varying lengths were allowable, as were unassigned bases between codons. An environmental supply of activated compounds for early evolving entities is proposed. An environmental NA replication process via single template-directed bond formation events is proposed. An environmental retention and redistribution process is proposed to have acted as a functional substitute for the cell wall and cell division of early evolving entities.     

Bootstrapping model of the origin of life

The origin of life is analyzed in terms of the self-facilitating aspect of evolution. According to the self-facilitation (or bootstrap) principle the structure of biological systems becomes increasingly suited to effective evolutionary search through the process of evolution. The principle may be extended to primitive collections of polymers with catalytic properties. The origin of the code may be based on a form of bootstrapping evolution. Once a primitive code appeared it could become more sophisticated through a multi-coding mechanism together with classical Darwinian mechanisms. The bootstrapping principle is also formulated in terms of the fluctuation-instability framework of Prigogine, Nicolis, and Babloyantz. Primitive collections of polymers accumulate evolution-enhancing redundancies which tend to reduce the extent to which they change when destabilized by fluctuation, but which increase the chances that these changes will lead to new predominant regimes. We show that the bootstrapping of evolutionary amenability is accompanied by the accumulation of a thermodynamic load, that is, a free energy cost which reduces the mechanistic efficiency. The bootstrapping effect suggests that the origin of life is most fruitfully approached as a long process during which the capacity to evolve facilitates itself in a step by step fashion rather than as a series of low probability events.