2.2 Endosymbiotic TheoryOnline version Steps to Endosymbiotic Theory by Jorge Arizpe 1 Primitive anaerobic prokaryotic cell (without nucleus, does not use oxygen in its respiration and does not perform photosynthesis). 2 Cell where part of its membrane has invaginated forming a nucleus (primitive Eukaryote) 3 Eukaryotic cell incorporates (phagocytic) aerobic bacteria (they use oxygen in their respiration) 4 Phagocytized aerobic bacteria become mitochondria. 5 Cell with nucleus and mitochondria, consumes (phagocyte) photosynthetic prokaryotic. 6 Photosynthetic prokaryotes become chloroplasts. 7 Eukaryotic, aerobic and photosynthetic cell (with a nucleus, it uses oxygen to oxidize its food in mitochondria and carries out photosynthesis in chloroplasts). 8 Aerobic eukaryotic cell (with nucleus and mitochondria that uses oxygen in its respiration)