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[Free report] The origin of life on our Earth |
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by Diana Gamazova | 17-03-2021 14:28
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Hello! So today I want to introduce to one of the most controversial and interesting topics I have ever encountered - the Origin of life! Early ideas and hypotheses about the origin of life The problem of life and the living is the object of research in many natural disciplines, starting with biology and ending with philosophy, mathematics, which consider abstract models of the phenomenon of the living, as well as physics, which defines life from the standpoint of physical laws. All other more specific problems and questions are concentrated around this main problem, as well as philosophical generalizations and conclusions are built. In accordance with two worldview positions — materialistic and idealistic — even in ancient philosophy, opposite concepts of the origin of life were formed: creationism and the materialistic theory of the origin of organic nature from inorganic nature. Proponents of creationism claim that life arose as a result of an act of divine creation, as evidenced by the presence in living organisms of a special force that controls all biological processes. Proponents of the origin of life from inanimate nature claim that organic nature arose due to the action of natural laws. Later, this concept was concretized in the idea of self-generation of life. The concept of self-generation, despite its fallacy, has played a positive role; the experiments designed to confirm it have provided a rich empirical material for the developing biological science. The final rejection of the idea of self-generation occurred only in the XIX century. In the XIX century, the hypothesis of the eternal existence of life and its cosmic origin on Earth was also put forward. It has been suggested that life exists in space and is transported from one planet to another. At the beginning of the XX century, the idea of the cosmic origin of biological systems on Earth and the eternity of life in space was developed by the Russian scientist Academician V. I. Vernadsky. The hypothesis of Academician A. I. Oparin A fundamentally new hypothesis of the origin of life was presented by academician A. I. Oparin in the book "The Origin of Life", published in 1924. He argued that the Redi principle, which introduces the monopoly of biotic synthesis of organic substances, is valid only for the modern era of the existence of our planet. At the beginning of its existence, when the Earth was lifeless, abiotic syntheses of carbon compounds and their subsequent prebiological evolution took place on it. The essence of Oparin's hypothesis is as follows: the origin of life on Earth is a long evolutionary process of the formation of living matter in the depths of inanimate matter. This happened through chemical evolution, as a result of which the simplest organic substances were formed from inorganic ones under the influence of strong physical and chemical processes. He considered the emergence of life as a single natural process, which consisted of the initial chemical evolution that took place in the conditions of the early Earth, which gradually moved to a qualitatively new level — biochemical evolution. Considering the problem of the origin of life through biochemical evolution, Oparin identifies three stages of the transition from inanimate matter to living matter. The first stage is chemical evolution. When the Earth was still lifeless (about 4 billion years ago), abiotic synthesis of carbonaceous compounds and their subsequent prebiological evolution took place on it. This period of the Earth's evolution was characterized by numerous volcanic eruptions with the release of a huge amount of hot lava. As the planet cooled, the water vapors in the atmosphere condensed and rained down on the Earth in torrents, forming vast expanses of water (the primary ocean). These processes continued for many millions of years. Various inorganic salts were dissolved in the waters of the primary ocean. In addition, various organic compounds continuously formed in the atmosphere under the influence of ultraviolet radiation, high temperature and active volcanic activity also fell into the ocean. The concentration of organic compounds constantly increased, and, eventually, the ocean waters became a "broth" of protein-like substances-peptides. The second stage is the appearance of protein substances. As the conditions on Earth softened, under the influence of electrical discharges, thermal energy and ultraviolet rays on the chemical mixtures of the primary ocean, it became possible to form complex organic compounds-biopolymers and nucleotides, which, gradually combining and becoming more complex, turned into protobionts (precellular ancestors of living organisms). The result of the evolution of complex organic substances was the appearance of coacervates, or co-acervate drops. Coacervates are complexes of colloidal particles, the solution of which is divided into two layers: a layer rich in colloidal particles, and a liquid almost free of them. Coacervates had the ability to absorb various substances dissolved in the waters of the primary ocean. As a result, the internal structure of the coacervates changed in the direction of increasing their stability in constantly changing conditions. The theory of biochemical evolution considers coacervates as prebiological systems, which are groups of molecules surrounded by an aqueous shell. So, for example, coacervates are able to absorb substances from the environment, interact with each other, increase in size, etc. However, unlike living beings, co-acervate droplets are not capable of self-reproduction and self-regulation, so they can not be attributed to biological systems. The third stage is the formation of the ability to reproduce itself, the appearance of a living cell. During this period, natural selection began to operate, i.e., in the mass of coacervate droplets, the co - acsrvates that were most resistant to these environmental conditions were selected. The selection process has been going on for many millions of years. The preserved co-acervate droplets already possessed the ability to primary metabolism — the main property of life. At the same time, having reached a certain size, the mother drop disintegrated into daughter drops that retained the features of the mother structure. Thus, we can talk about the acquisition by coacervates of the property of self - production — one of the most important signs of life. In fact, at this stage, the coacervates turned into the simplest living organisms. Further evolution of these prebiological structures was possible only with the complication of metabolic processes within the cocervate. The internal environment of the coacervate needed protection from environmental influences. Therefore, around the coacervates rich in organic compounds, there were layers of lipids that separated the coacervate from the surrounding water environment. In the course of evolution, lipids were transformed into the outer membrane, which significantly increased the viability and stability of organisms. The appearance of the membrane determined the direction of further biological evolution along the path of increasingly perfect autoregulation, which ended with the formation of the primary cell-the archecell. The cell is an elementary biological unit, the structural and functional basis of all living things. Cells carry out an independent metabolism, are capable of division and self-regulation, i.e. they have all the properties of a living being. The formation of new cells from non-cellular material is impossible, cell reproduction occurs only through division. Organic development is considered as a universal process of cell formation. In the structure of the cell, there are: a membrane that separates the contents of the cell from the external environment; a cytoplasm, which is a saline solution with soluble and suspended enzymes and RNA molecules; a nucleus containing chromosomes consisting of DNA molecules and proteins attached to them. Therefore, the beginning of life should be considered the emergence of a stable self-reproducing organic system (cell) with a constant sequence of nucleotides. Only after the emergence of such systems can we talk about the beginning of biological evolution. The possibility of abiogenic synthesis of biopolymers was experimentally proved in the middle of the XX century. In 1953, the American scientist S. Miller modeled the primary atmosphere of the Earth and synthesized acetic and formic acids, urea and amino acids by passing electric charges through a mixture of inert gases. Thus, it was demonstrated how the synthesis of complex organic compounds is possible under the influence of abiogenic factors. Despite its theoretical and experimental validity, Oparin's concept has both strengths and weaknesses. The strong point of the concept is a fairly accurate experimental justification of chemical evolution, according to which the origin of life is a natural result of the prebiological evolution of matter. A convincing argument in favor of this concept is also the possibility of experimental verification of its main provisions. The weak side of the concept is the impossibility of explaining the very moment of the jump from complex organic compounds to living organisms. One of the versions of the transition from prebiological to biological evolution is proposed by the German scientist M. Eigen. According to his hypothesis, the origin of life is explained by the interaction of nucleic acids and proteins. Nucleic acids are carriers of genetic information, and proteins serve as catalysts for chemical reactions. Nucleic acids reproduce themselves and transmit information to proteins. There is a closed chain-a hypercycle, in which the processes of chemical reactions are self-accelerated due to the presence of catalysts and congestion. In hypercycles, the reaction product simultaneously acts as both a catalyst and a starting reagent. Such reactions are called autocatalytic. Another theory that can explain the transition from prebiological to biological evolution is synergetics. The patterns discovered by synergetics allow us to clarify the mechanism of the emergence of organic matter from inorganic matter in terms of self-organization through the spontaneous emergence of new structures during the interaction of the open system with the environment.
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3 Comments
Hi Diana
thanks for sharing this informative report on origin of life.
keep writing
Posted 01-04-2021 22:06
Hi Diana,
This is your mentor Debbie. :)
Wow! What a lengthy report! It took me a good while to finish reading, haha. Well, there are so many hypotheses. It??s hard to believe that to this day, with all the scientific and technological advances, we are still yet to find out the Origin of Life. This actually goes back to a philosophical issue as well. A very complex issue indeed.
Next time when you??re writing a report, it would be nice of you could include some picture or infographic references! It might make it a little easier to understand what you would like to convey to the readers.
Keep up with the work! :)

Green Cheers,
Debbie
Posted 20-03-2021 21:06
Hi Diana, this is your mentor Yuseon:D
Thank your for your interesting report of the Origin of Life.
Actually this might be a sensitive issue with the controversy of the religious point of view, and the scientific ones. You have mentioned both, but I believe you put more emphasis in the latter, explaining the hypothesis of Oparin.
Thanks for the detailed information, and full story of Oparin's progress in his theory. Caught some good information while reading it:)
Keep up the good work,
Yuseon
Posted 19-03-2021 16:04