1.5  The Origin of Cells

big ninja

Essential Idea:

There is an unbroken chain of life from the first cells

on Earth to all cells in organisms alive today


  • Cells can only be formed by division of pre-existing cells
  • The first cells must have arisen from non-living material
  • The origin of eukaryotic cells can be explained by the endosymbiotic theory


  • Evidence from Pasteur’s experiments that spontaneous generation of cells and organisms does not now occur on Earth