oparin theory on origin of life
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1. The Atomic Phase:
Early earth had innumerable atoms of all those elements (e.g., hydrogen, oxygen, carbon, nitrogen, sulphur, phosphorus, etc.) which are essential for the formation of protoplasm. Atoms were segregated in three concentric masses according to their weights, (a) The heaviest atoms of iron, nickel, copper, etc. were found in the centre of the earth, (b) Medium weight atoms of sodium, potassium, silicon, magnesium, aluminium, phosphorus, chlorine, fluorine, sulphur, etc. were collected in the core of the earth, (c) The lightest atoms of nitrogen, hydrogen, oxygen, carbon etc. formed the primitive atmosphere.
2. Formation of Inorganic Molecules:
ADVERTISEMENTS:
Free atoms combined to form inorganic molecules such as H2 (Hydrogen), N2 (Nitrogen), H20 (Water vapour), CH4 (Methane), NH3 (Ammonia), C02 (Carbon dioxide). Hydrogen atoms were most numerous and most reactive in primitive atmosphere.
First hydrogen atoms combined with all oxygen atoms to form water and leaving no free oxygen. Thus primitive atmosphere was reducing atmosphere (without free oxygen) unlike the present oxidising atmosphere (with free oxygen).
Hydrogen atoms also combined with nitrogen, forming ammonia (NH3). So water and ammonia were probably the first molecules of primitive earth.
3. Formation of Simple Organic Molecules (Monomers):
The early inorganic molecules interacted and produced simple organic molecules such as simple sugars (e.g., ribose, deoxyribose, glucose, etc.), nitrogenous bases (e.g., purines, pyrimidines), amino acids, glycerol, fatty acids, etc.
Torrential rains must have fallen. As the water rushed down, it must have dissolved away and carried with it salts and minerals, and ultimately accumulated in the form of oceans. Thus ancient oceanic water contained large amounts of dissolved NH3, CH4, HCN, nitrides, carbides, various gases and elements.
CH4 + C02 + H20 —> Sugars + Glycerol + Fatty Acids
CH4 + HCN + NH3 + H20 —> Purines + Pyrimidines
ADVERTISEMENTS:
CH4 + NH3 + C02 + H20 —> Amino Acids
Some external sources must have been acting on the mixture for reactions. These external sources might be (i) solar radiations such as ultra-violet light, X-rays, etc., (ii) energy from electrical discharges like lightning, (iii) high energy radiations are other sources of energies (probably unstable isotopes on the primitive earth). There was no ozone layer in the atmosphere.
A soup-like broth of chemicals formed in oceans of the early earth from which living cells are believed to have appeared, was termed by J.B. Haldane (1920) as ‘prebiotic soup’ (also called ‘hot dilute soup’). Thus the stage was set for combination of various chemical elements. Once formed, the organic molecules accumulated in water because their degradation was extremely slow in the absence of any life or enzyme catalysts.
Experimental Evidence for Abiogenic Molecular Evolution of Life:
Stanley Miller in 1953, who was then a graduate student of Harold Urey (1893-1981) at the University of Chicago, demonstrated it clearly that ultra-violet radiation or electrical discharges or heat or a combination of these can produce complex organic compounds from a mixture of methane, ammonia, water (stream of water), and hydrogen. The ratio of methane, ammonia and hydrogen in Miller’s experiment was 2:1:2.
Miller circulated four gases— methane, ammonia, hydrogen and water vapour in an air tight apparatus and passed electrical discharges from electrodes at 800°C. He passed the mixture through a condenser.
He circulated the gases continuously in this way for one week and then analysed the chemical composition of the liquid inside the apparatus. He found a large number of simple organic compounds including some amino acids such as alanine, glycine and aspartic acid. Miller conducted the experiment to test the idea that organic molecules could be synthesized in a reducing environment.
Other substances, such as urea, hydrogen cyanide, lactic acid and ace
Early earth had innumerable atoms of all those elements (e.g., hydrogen, oxygen, carbon, nitrogen, sulphur, phosphorus, etc.) which are essential for the formation of protoplasm. Atoms were segregated in three concentric masses according to their weights, (a) The heaviest atoms of iron, nickel, copper, etc. were found in the centre of the earth, (b) Medium weight atoms of sodium, potassium, silicon, magnesium, aluminium, phosphorus, chlorine, fluorine, sulphur, etc. were collected in the core of the earth, (c) The lightest atoms of nitrogen, hydrogen, oxygen, carbon etc. formed the primitive atmosphere.
2. Formation of Inorganic Molecules:
ADVERTISEMENTS:
Free atoms combined to form inorganic molecules such as H2 (Hydrogen), N2 (Nitrogen), H20 (Water vapour), CH4 (Methane), NH3 (Ammonia), C02 (Carbon dioxide). Hydrogen atoms were most numerous and most reactive in primitive atmosphere.
First hydrogen atoms combined with all oxygen atoms to form water and leaving no free oxygen. Thus primitive atmosphere was reducing atmosphere (without free oxygen) unlike the present oxidising atmosphere (with free oxygen).
Hydrogen atoms also combined with nitrogen, forming ammonia (NH3). So water and ammonia were probably the first molecules of primitive earth.
3. Formation of Simple Organic Molecules (Monomers):
The early inorganic molecules interacted and produced simple organic molecules such as simple sugars (e.g., ribose, deoxyribose, glucose, etc.), nitrogenous bases (e.g., purines, pyrimidines), amino acids, glycerol, fatty acids, etc.
Torrential rains must have fallen. As the water rushed down, it must have dissolved away and carried with it salts and minerals, and ultimately accumulated in the form of oceans. Thus ancient oceanic water contained large amounts of dissolved NH3, CH4, HCN, nitrides, carbides, various gases and elements.
CH4 + C02 + H20 —> Sugars + Glycerol + Fatty Acids
CH4 + HCN + NH3 + H20 —> Purines + Pyrimidines
ADVERTISEMENTS:
CH4 + NH3 + C02 + H20 —> Amino Acids
Some external sources must have been acting on the mixture for reactions. These external sources might be (i) solar radiations such as ultra-violet light, X-rays, etc., (ii) energy from electrical discharges like lightning, (iii) high energy radiations are other sources of energies (probably unstable isotopes on the primitive earth). There was no ozone layer in the atmosphere.
A soup-like broth of chemicals formed in oceans of the early earth from which living cells are believed to have appeared, was termed by J.B. Haldane (1920) as ‘prebiotic soup’ (also called ‘hot dilute soup’). Thus the stage was set for combination of various chemical elements. Once formed, the organic molecules accumulated in water because their degradation was extremely slow in the absence of any life or enzyme catalysts.
Experimental Evidence for Abiogenic Molecular Evolution of Life:
Stanley Miller in 1953, who was then a graduate student of Harold Urey (1893-1981) at the University of Chicago, demonstrated it clearly that ultra-violet radiation or electrical discharges or heat or a combination of these can produce complex organic compounds from a mixture of methane, ammonia, water (stream of water), and hydrogen. The ratio of methane, ammonia and hydrogen in Miller’s experiment was 2:1:2.
Miller circulated four gases— methane, ammonia, hydrogen and water vapour in an air tight apparatus and passed electrical discharges from electrodes at 800°C. He passed the mixture through a condenser.
He circulated the gases continuously in this way for one week and then analysed the chemical composition of the liquid inside the apparatus. He found a large number of simple organic compounds including some amino acids such as alanine, glycine and aspartic acid. Miller conducted the experiment to test the idea that organic molecules could be synthesized in a reducing environment.
Other substances, such as urea, hydrogen cyanide, lactic acid and ace
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Answer:
✔Theory of special creation:
It states that God created life by his divine act of creation.
✔Theory of Panspermia/Cosmozoic:
It stated that the spores or panspermia cane from outer space and developed into living forms.
✔Theory of spontaneous generation:
It stated that life originated from decaying and rotting matter like straw, mud, etc.
✔Theory of chemical evolution or Oparin-Haldane theory:
Life originated from pre-existing non-living organic molecules and that formation of life was preceded by chemical evolution.
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