1. Endosymbiotic Theory

2. Endosymbiosis
Symbiosis, which means "living together" is an ecological interaction in which two or more species live in or on each other in close contact. Thus, endosymbiosis is when an organism actually lives within another organism.

3. The Endosymbiotic Theory
The endosymbiotic theory is the idea that a long time ago, prokaryotic cells engulfed other prokaryotic cells by endocytosis. This resulted in the first eukaryotic cells.
First proposed by Lynn Margulis
Explains the origin of eukaryotic cells
Explains the origin of certain membrane-bound organelles

4. What Exactly Happened? Ancient Prokaryotes
Chloroplast
Plants and plant-like protists
Ancient Prokaryotes
Heterotrophic bacteria
Nuclear envelope evolving
Photosynthetic bacteria
Mitochondrion
Primitive Autotrophic (Photosynthetic) Eukaryote
Animals, fungi, and animal-like protists
Ancient Heterotrophic Prokaryote
Primitive Heterotrophic Eukaryote

5. Evidence in support of the endosymbiotic theory:
Similarities between mitochondria, chloroplasts, & prokaryotes:
Circular DNA
Ribosomes
Binary fission

6. Questions Explain the Endosymbiotic Theory.
What does “symbiosis” mean?
Based on this theory, how did chloroplasts and mitochondria arise?