The Origin of Cells

The Origin of Cells

1. Cell division and the origin of cells

   • can only form by division of pre-existing cells
   • all cells in our body came from a zygote
     • the zygote formed through the fusion a sperm and egg cell
       • our parents can be traced back to their zygotes
         • this traces back millions of years and shows our origins
   • cell artificially developed in 2010
   • original theory was spontaneous generation
     • disproved by Louis Pasteur

2. Origin of the first cells

   • must have arisen from non-living material
   • theories
     • production of carbon compounds
     • assembly of carbon compounds into polymers
     • Development of a mechanism for inheritance
     • Membrane formation

3. Endosymbiosis and eukaryotic cells

   • creation of eukaryotic cells explained by endosymbiotic theory
     • mitochodria - free living prokaryotic organisms
     • mit. developed aerobic processes
     • Larger anaerobic prokaryotes took them in by endocytosis
     • allowed them to live in cytoplasm
     • evolved to today's eukaryotic cells
     • prok. features of mit. and chloroplasts
       • circular molecule with genes
       • prok. like 70S ribosomes
       • transcribe own DNA
       • use mRNA to synthesize own proteins
       • only can be produced by division of pre-existing
   • two prokaryotes in symbiotic relationship
     • mutualistic
     • food for mit.
     • energy for large prok.
   • natural selection
   • also applies to chloroplasts