Theory of Chemical/Biochemical evolution/Modern theory of the origin of life/Operin-Haldane theory of the origin of life/ Materialistic Theory or Physico-chemical (Part -1)
Theory of Chemical/Biochemical evolution/Modern theory of origin of life/Operin-Haldane theory of origin of life/ Materialistic Theory or Physico-chemical Theory:
Gradual transformation (transmutation) of inorganic compounds to organic compounds and organic compounds to protocell (life) is called the Biochemical origin of life. Modern biologists agree that the origin of life was a continuous steady process. Life did not come into existence suddenly but was a result of a long series of physicochemical changes. These changes brought about a gradual evolution of the first inorganic and then organic compounds in accordance with the ever-changing environmental conditions. The concept of a biochemical origin of life was first proposed by Russian biochemist A.I. Oparin in 1923 and later supported by English scientist J.B.s Haldane in 1928. Thus, this theory is also called Oparin and Haldane theory.
Later, in the year 1936, Oparin published his views in his book, The Origin of Life. The whole series of events, as envisaged by Oparin and Haldane, can be divided into the following eight steps.
A) Origin of earth and its primitive atmosphere: When the earth was broken from the sun, it was a glowing fire and a rotating cloud of hot gasses, vapors of various elements, pieces of rocks, and metals called nebulously. As the earth was moving away from the sun, the temperature slowly decreased. This led to the condensation of gases. The lightest elements (He, H, O, N, C) occupied the atmosphere of the eart
B) Formation of ammonia, water, and methane: The earth was very hot (5000-6000 °C) initially and so the atoms could not combine with each other easily. It contains H, O, N, and C. Hydrogen was very reactive it combined with nitrogen to form ammonia, with oxygen to form water, with carbon to form methane.
N2+ 3H2→ 2NH2 (gas)
C +2H2→ CH4 (gas)
2H2+ O2→ 2H2O (steam)
As the temperature is high ammonia and methane remained as gas and water as steam. As temperature decreases steam condensed to water which results in rain and the earth become cold. Water gradually accumulated and this led to the formation of rivers, sea lakes, etc. Thus the first chemicals formed on the earth were water, ammonia, methane, etc.
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