We explain what is Oparin's Theory about the origin of life and his criticisms about it. Also, how is the scheme of this theory.
What is Oparin's Theory?
The Oparin Theory is known as the explanation proposed by the Soviet biochemist Aleksandr Ivanovich Oparin (1894-1980) to answer the question about the origin of the life, once completely rejected the Theory of spontaneous generation.
Oparin proposed that life would have appeared gradually from the emergence of substances complex in the Earth primitive, from inanimate matter (abiogenesis).
This theory was presented in 1922 to the Moscow botanical society, and although it initially received strong criticism and discredit, it was later experimentally corroborated. As a result, in 1970 Oparin was elected president of the International Society for the Study of the Origins of Life.
Oparin's Theory took advantage of the scientist's knowledge in astronomy, from which he knew that the atmospheres of other planets and astros there are 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 would have served as raw material for life.
This, according to Oparin, would have happened thanks to the heat of the primitive Earth and to ultraviolet radiation or the electrical discharges of the atmosphere, which provided the energy needed to set in motion the molecular reactions that would lead to amino acids, peptide bonds, and eventually proteins, suspended in colloids on the planet's surface. There thecoacervates, called laterprobionts.
From the coacervate to the cell
Continuing with Oparin's Theory, the coacervates would have been stable globules of protein 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 promoting) the synthesis of new macromolecules of nucleoproteins, precursors of the genetic material that we know today.
The coacervates, then, would have enveloped said nucleoproteins and would have formed structures around them, until eventually certain lipids they formed small lipoprotein membranes. Thus would have been born the first protocell, the first and most rudimentary forms of life on the planet.
Among these primitive cells, competition and natural selection, pushing them towards an evolutionary race that would engender all forms of life 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:
- Abiogenic synthesis. Formation of the first organic compounds from the inorganic material.
- Polymerization. Formation of long chains of macromolecules complexes under the action of various sources of Energy, thus achieving complex and essential compounds for life: proteins, polysaccharides and nucleic acids.
- Coacervation. Formation of coacervates, that is, of microscopic aggregates of proteins and polymers separated from the environment by a protomembrane. Are not living beings, but they are the step immediately before.
- Origin of the primitive cell. The incorporation of nucleic acids into the coacervates allowed inheritance and therefore natural selection, properly giving rise to life in the form of the first autotrophic cells.