We explain to you what Oparin’s Theory is about the origin of life and its criticisms about it. Also, how is the scheme of this theory.
What is the Oparin Theory?
The theory of Oparin is known as the explanation proposed by the Soviet biochemist Aleksandr Ivánovich Oparin (1894-1980) to answer the question about the origin of life , once the theory of spontaneous generation is completely rejected .
Oparin proposed that life would have appeared gradually from the emergence of complex substances on the primitive Earth, from inanimate matter (abiogenesis).
This theory was presented in 1922 to the botanical society of Moscow, and although initially they received strong criticism and discredit, they were subsequently corroborated experimentally. Thanks to this, in 1970 Oparin was elected as president of the International Society for the Study of the Origins of Life.
The theory of Oparin took advantage of the knowledge of the scientist in astronomy , from which he knew that the atmospheres of other planets and stars exist substances such as ammonia, methane and hydrogen, which serve as a substrate to obtain nitrogen, carbon and hydrogen respectively: materials that together with the oxygen of the water and the atmosphere they would have served as raw material for life.
This, according to Oparin, would have happened thanks to the heat of the primitive Earth and ultraviolet radiation or electric discharges from the atmosphere , which provided the energy needed to start the molecular reactions that would lead to amino acids, peptide bonds and eventually to proteins, suspended in colloids on the planet’s surface. There would have arisen the coacervados , then called probiontes .
From coacervate to cell
Continuing with the Oparin Theory, the coacervates would have been stable protein globules held together by electrostatic forces, which tended to self-synthesize in a medium rich in proteins, sugars and nucleic acids.
Some of these proteins would have acted as enzymes , catalyzing (accelerating or propitiating) the synthesis of new nucleoprotein macromolecules, precursors of the genetic material that we know today.
The coacervates, then, would have enveloped said nucleoproteins and formed structures around them, until eventually certain lipids formed small lipoprotein membranes. Thus the first protocell was born, the first and most rudimentary forms of life on the planet.
Among these primitive cells, competition and natural selection would have begun to operate, pushing them towards an evolutionary career that would engender all life forms known to date, in a long and complex process of change and adaptation to environmental conditions.
Oparin’s theory can be summarized in the following scheme:
- Synthesis abiogenic . Formation of the first organic compounds from inorganic matter.
- Polymerization . Formation of long chains of complex macromolecules under the action of various energy sources, thus achieving complex and indispensable compounds for life: proteins, polysaccharides and nucleic acids.
- Coacervation . Formation of coacervates, that is, microscopic aggregates of proteins and polymers separated from the environment by a protomembrane. They are not living beings, but they are the immediately previous step.
- Origin of the primitive cell . The incorporation into the coacervates of nucleic acids allowed inheritance and therefore natural selection, giving rise to life itself in the form of the first autotrophic cells.