The theory is also
called as chemosynthetic theory.
The theory regarding abiogenic origin of life
was proposed independently by
- Alexander Ivanovich Oparin; Russian Biochemist 1923
- J.B.S Haldene; British Biologist 1929
According to this theory; the conditions of
primitive atmosphere
- No free Oxygen or Ozone
- High Temperature; therefore everything in Gaseous state
- H2, H2O (water vapor) NH3, CO2 and CH4, H2S, HCN were present
Gradual Cooling of earth
Water vapor condensed followed by torrential
rain forming ocean
All these chemicals in Ocean H2, H2O (water
vapour) NH3, CO2 and CH4, H2S, HCN (hot dilute organic soup)
Energy source for reactions were from lightning,
UV rays, ionizing radiations, volcanic activities.
Let us divide the theory into different stages
for better understanding
You can watch this video for better understanding
Stage 1
Abiogenic Formation of organic compounds from inorganic
compounds
- Free Atoms like C, H, O and N combined to form simple inorganic compounds
- Abiotic synthesis of Monomers from simple inorganic compounds such as H2, H2O, CH4 and NH3
- Simple organic compounds or monomers such as amino acids (protein), purines, pyramidines (nucleotides), monosaccharide (carbohydrates), fatty acids, glycerol (lipids) were formed from H2, H2O, CH4 and NH3 in ocean.
Stage 2: Formation of Haldenes pre biotic soup
or Hot dilute soup
- Haldene called this chemical cocktail in ocean as hot dilute soup.
- These monomers combined to form polymers like Proteins, Nucleic acids, fats and polysaccharides.
Stage 3: Coacervate formation (Oparin’s
coacervates) after formation of a colloid system
- Coacervates are small liquid droplets or group of organic molecules covered by water membrane.
- It is capable of division and exchange substances with the environment.
- The complexity of coacervates gradually increased by accommodating many organic polymers inside the membrane
Stage 4: Complex Coacervate finally formed proto
cells or first living unit.
- Protocells are lipid membrane bound structures with nucleic acid regulation and enzyme controlled metabolism; just like a primitive cell.
- These protocells could grow, divide and exchange materials with the surroundings. Protocells with successful adaptations are selected to divide and gradually evolved to form the most primitive cell. It later evolved into heterotrophic cell. Later chlorophyll molecules were formed forming autotrophs.
Now many theories were proposed explaining the
origin if life. But this theory paved way to a new research area focusing on
biomolecules and its association with regard to the origin of life.