Question

List out possible steps by which simple inorganic substances gave rise to complex organic molecules which eventually gave rise to first cell.

Answer 1

1. Simple gases and inorganic substances were present in the primitive atmosphere, which lacked free oxygen.
2. Energy from lightning, ultraviolet radiation, radioactive rocks and volcanoes drove the formation of small organic molecules, including sugars, amino acids and nitrogenous bases.
3. Rain carried these molecules into the oceans, where they accumulated in the primordial soup.
4. Small molecules combined to form polymers such as proteins, polysaccharides and nucleic acids.
5. Organic molecules gathered into aggregates such as coacervates or other protobiont-like structures; these were not themselves living cells.
6. The earliest cells are thought to have been simple anaerobic heterotrophs using organic molecules already present in their environment. 

The proposed sequence proceeds from simple chemistry to organic molecules, polymers, cell-like systems and finally primitive cells.