Download Endosymbiosis - Summit Academy High School

Where did all the fancy organelles come from?
Figure 2.3
Figure 2.23
Figure bx 2.1
Figure bx 2.1
“On the Origin of
Mitosing Cells”
Lynn Margolis, 1967
The Endosymbiotic Theory
The Endosymbiotic Theory
A good theory makes predictions…
…so if endosymbiosis is a good theory, then what would we predict?
The Endosymbiotic Theory predicts that Mitochondria should show the following features:
1. Circular DNA as in bacteria
2. Similar genes to bacteria
3. Small ribosomes as in bacteria
4. Similar proteins to bacteria
5. Double membrane
• Inner membrane is like bacteria
• Outer membrane is like eukaryotic host
6. Similar lipids to bacteria
7. Replicate by binary fission like bacteria
8. The cell cannot make more mitochondria (mitochondria have to replicate themselves)
9. Similar in size to bacteria (sort of, but when you reach graduate school you’ll learn that
this isn’t really accurate)
Note: while it is true that “makes ATP” is a feature of mitochondria, it is not a feature
predicted by the Endosymbiotic Theory.