Prebiotic evolution Dotaz Zobrazit nápovědu
Synthesis of RNA nucleobases from formamide is one of the recurring topics of prebiotic chemistry research. Earlier reports suggest that thymine, the substitute for uracil in DNA, may also be synthesized from formamide in the presence of catalysts enabling conversion of formamide to formaldehyde. In the current paper, we show that to a lesser extent conversion of uracil to thymine may occur even in the absence of catalysts. This is enabled by the presence of formic acid in the reaction mixture that forms as the hydrolysis product of formamide. Under the reaction conditions of our study, the disproportionation of formic acid may produce formaldehyde that hydroxymethylates uracil in the first step of the conversion process. The experiments are supplemented by quantum chemical modeling of the reaction pathway, supporting the plausibility of the mechanism suggested by Saladino and coworkers.
This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).
PRINCIPLES OF MOLECULAR SELECTION AND EVOLUTION -- 4. Models of Prebiotic Translation -- 103 -- 104 -- 109 -- 118 -- 129 -- 130 -- 133 -- 135 -- 138 -- 149 The Evolution of Hypercycles 228 -- 11.1. Self-Organization of Catalytic Hypercycles 229 -- 11.2. Evolution in the Test-Tube 257 -- 13.1. The Qp Replicase System 258 -- 13.2. Experimental Perspectives: An Evolution Machine 272 -- 14.
ix, 321 s. : il., tab., grafy ; 26 cm
- MeSH
- chemické jevy MeSH
- molekulární evoluce MeSH
- Publikační typ
- monografie MeSH
In this work, we provide an answer to the question formulated by Albert Eschenmoser: "How would you envisage the bridge between potentially primordial geochemistry that had been disordered and one that gradually became self-organizing?" Analysis of the free-energy profiles of some of the key reactions leading to formation of nucleotides and their oligomers shows that, whereas the first part of the pathway, up to nucleotides, is energy-driven, in the second low-energy part entropic control in the form of structural compatibility becomes more important. We suggest that the birth of modern metabolism requires structural compatibility, which is enabled by the commensurability of the thermodynamics of the synthetic steps with the stabilizing effect of those intermolecular interactions that play a key role in dictating entropic control of these reactions.
Prebiotic nucleotide synthesis is crucial to understanding the origins of life on Earth. There are numerous candidates for life's first nucleic acid, however, currently no prebiotic method to selectively and concurrently synthesise the canonical Watson-Crick base-pairing pyrimidine (C, U) and purine (A, G) nucleosides exists for any genetic polymer. Here, we demonstrate the divergent prebiotic synthesis of arabinonucleic acid (ANA) nucleosides. The complete set of canonical nucleosides is delivered from one reaction sequence, with regiospecific glycosidation and complete furanosyl selectivity. We observe photochemical 8-mercaptopurine reduction is efficient for the canonical purines (A, G), but not the non-canonical purine inosine (I). Our results demonstrate that synthesis of ANA may have been facile under conditions that comply with plausible geochemical environments on early Earth and, given that ANA is capable of encoding RNA/DNA compatible information and evolving to yield catalytic ANA-zymes, ANA may have played a critical role during the origins of life.
The Structure of Adaptive Landscapes Underlying Protein Evolution, 121 -- Adaptive Maturation of the Immune Response, 122 Evolution of Novel Catalytic Functions, 142 -- Applied Molecular Evolution: Direct - PART III ORDER AND ONTOGENY, 407 -- 11 The Architecture of Genetic Regulatory Circuits and Its Evolution , 411 -- Independence of the Molecular Evolutionary Clock and Morphological Evolution, 412 -- CONTENTS
1st ed. 709 s. : il.
- Klíčová slova
- Biologie, Evoluce, Fylogeneze,
- MeSH
- biologická evoluce MeSH
- biologie MeSH
- fylogeneze MeSH
- molekulární evoluce MeSH
- původ života MeSH
The primordial origin of abiotic nitrogen fixation, which is not dependent on prokaryotes, reflects the importance of available nitrogenous compounds as an essential requirement for the emergence of life and evolutionary biodiversity. It has been hypothesized that synthesis of oxidized nitrogen in the form of nitrate (NO3-) and nitrite (NO2-), occurred in the prebiotic anoxic Hadean atmosphere. The sustained influx of atmospheric NO3- and NO2- into prebiotic Hadean oceans have been proposed to provide the essential substrates for abiotic synthesis of compounds such as ammonia (NH3) within oceanic alkaline hydrothermal vents in the seafloor. Because NH3 is an essential chemical precursor for nitrogen-containing molecular components of proteins and nucleic acids, abiotic production in high concentrations within Hadean oceanic alkaline hydrothermal vents is required for the emergence of diverse life forms. The chemical evolution of nitrogenous compounds includes the functional development of alkaloids. This commentary aims to critically discuss the possible origin of nitrogen-containing alkaloids and evolutionary processes in higher organisms, including the diverse biomedical mechanisms involved.
- MeSH
- alkaloidy * MeSH
- biodiverzita * MeSH
- biologická evoluce * MeSH
- hydrotermální průduchy * MeSH
- oceány a moře MeSH
- Publikační typ
- úvodníky MeSH
- Geografické názvy
- oceány a moře MeSH
There is a huge variety of RNA- and DNA-containing entities that multiply within and propagate between cells across all kingdoms of life, having no cells of their own. Apart from cellular organisms, these entities (viroids, plasmids, mobile elements and viruses among others) are the only ones with distinct genetic identities but which are not included in any traditional tree of life. We suggest to introduce or, rather, revive the distinct category of acellular organisms, Acytota, as an additional, undeservedly ignored full-fledged kingdom of life. Acytota are indispensable players in cellular life and its evolution. The six traditional kingdoms (Cytota) and Acytota together complete the classification of the biological world (Biota), leaving nothing beyond.
- MeSH
- biologická evoluce * MeSH
- původ života * MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
We outline novel findings on the non-enzymatic polymerization of nucleotides under plausible prebiotic conditions and on the spontaneous onset of informational complexity in the founding molecule, RNA. We argue that the unique ability of 3', 5' cyclic guanosine monophosphate to form stacked architectures and polymerize in a self-sustained manner suggests that this molecule may serve as the 'seed of life' from which all self-replicating oligonucleotides can be derived via a logically complete sequence of simple events. WIREs RNA 2017, 8:e1400. doi: 10.1002/wrna.1400 For further resources related to this article, please visit the WIREs website.
- MeSH
- lidé MeSH
- molekulární evoluce * MeSH
- oligonukleotidy metabolismus MeSH
- původ života * MeSH
- RNA metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
