Origin of cells

• 1.3.1 Pasteur’s soup: A prior belief was that cells could spontaneously arise from the assembly of inorganic matter. However, Louis Pasteur disputed the belief of spontaneous formation of life in the 19th century.
• In Pasteur's simple experiment, he filled two flasks with nourishing soup, a medium highly nutritious for microorganisms to thrive, and then sterilized them. One flask had a straight open neck, while the other had a curved opened neck. Within a week, the straight-necked soup was spoiled and the curved-necked soup was as good as it was on the first day.
• The germs found in the spoiled soup, could be found at the entrance of the curved necked, where they got stuck. Therefore, the mould, fungi and bacteria were able to enter the soup from the environment, but were not able to assemble from thin air in the sealed container.
• Forming cells


  Form complex molecules
• Miller-Urey experiment


  Showed that water vapour, ammonia and methane, all found in the early atmosphere, could have spontaneously assembled into amino acids and carbon compounds, in the presence of electricity (lightning)
• Phospholipids formed at that time on earth

  • They would have naturally assembled into bilayers, forming early membranes
• Formation of nucleic acids such as RNA


  1. Gave rise to early enzymatic activities

  2. Protein assembly

  3. First genetic information
• Endosymbiotic theory: this theory assumes that more complex eukaryotic cells have evolved from the prokaryotic cells through a symbiotic process.
• • Symbiosis is a mutually favourable coexistence of two organisms
• The theory suggests that a larger anaerobic prokaryotic cell could have engulfed a smaller aerobic cell, and started coexisting with it.
• • The large cell was supplying the smaller one with food, while the smaller cell was converting the food into energy for the larger cell → symbiosis.This would have given rise to mitochondria and chloroplasts.