This document provides an overview of a slide presentation about the endosymbiotic origins of mitochondria and chloroplasts. The presentation aims to teach students that mitochondria and chloroplasts evolved through endosymbiosis, which helps explain their unique cellular features, such as double membranes, circular DNA, ribosomes, and binary fission reproduction. The slides show how mitochondria likely originated from alpha-proteobacteria and chloroplasts from cyanobacteria, through these ancient endosymbiotic events. References are also provided for further reading on endosymbiotic theory.

1. Evolution connection: Mitochondria and Plastids
Learning goals:
Students will understand that 1) mitochondria and plastids evolved through
endosymbiosis, and 2) this evolutionary history helps us make sense of the
characteristics of these organelles.
For the instructor:
This short slide set explains endosymbiosis. To integrate it best, use these slides
immediately after you’ve discussed plant and animal cellular organelles. Slides 7 and
14 could be cut to save time.
Each of the following slides comes with a sample script for the instructor. To review
this script, download the PowerPoint file and view the Notes associated with each slide.

2. What is unique about the structure of mitochondria and
chloroplasts?
Evolution connection: Mitochondria and Plastids
• double membrane

3. What is unique about the structure of mitochondria and
chloroplasts?
Evolution connection: Mitochondria and Plastids
• double membrane
• their own DNA
Photo from Christian Kukat, Christian A. Wurm, Henrik Spåhr, Maria Falkenberg, Nils-Göran Larsson,
and Stefan Jakobs. Super-resolution microscopy reveals that mammalian mitochondrial nucleoids
have a uniform size and frequently contain a single copy of mtDNA. PNAS 2011 108 (33) 13534-
13539

4. What is unique about the structure of mitochondria and
chloroplasts?
Evolution connection: Mitochondria and Plastids
• double membrane
• their own CIRCULAR DNA
circular
chloroplast
chromosome
linear
mammalian
chromosome

5. What is unique about the structure of mitochondria and
chloroplasts?
Evolution connection: Mitochondria and Plastids
• double membrane
• their own circular DNA
• their own ribosomes
Image from Sukhjit Kaur, Reynald Gillet, Wen Li, Richard Gursky, and Joachim Frank. Cryo-EM
visualization of transfer messenger RNA with two SmpBs in a stalled ribosome PNAS 2006 103 (44)
16484-16489.

6. What is unique about the structure of mitochondria and
chloroplasts?
Evolution connection: Mitochondria and Plastids
• double membrane
• their own circular DNA
• their own ribosomes
• multiply by binary fission
Mitochondria image © Rockefeller University Press, 1970; originally published in the Journal of Cell
Biology 47:373-383. Chloroplast image from Shin-ya Miyagishima. Mechanism of Plastid Division:
From a Bacterium to an Organelle. Plant Physiol. 2011 155: 1533-1544.

7. What is unique about the structure of mitochondria and
chloroplasts?
Evolution connection: Mitochondria and Plastids
• double membrane
• their own circular DNA
• their own ribosomes
• multiply by binary fission

8. Why are mitochondria and chloroplasts so weird?
Evolution connection: Mitochondria and Plastids
• double membrane
• their own circular DNA
• their own ribosomes
• multiply by binary fission

9. Why are mitochondria and chloroplasts so weird?
Evolution connection: Mitochondria and Plastids
Because of their evolutionary history! Both evolved via
endosymbiosis.

10. Endosymbiosis in a series
1.
Evolution connection: Mitochondria and Plastids

11. Endosymbiosis in a series
1.
Evolution connection: Mitochondria and Plastids

12. Endosymbiosis in a series
2.
Evolution connection: Mitochondria and Plastids

13. Endosymbiosis in a series
2.
Evolution connection: Mitochondria and Plastids

14. Endosymbiosis in a series
3.
Evolution connection: Mitochondria and Plastids
dinoflagellate
euglenoid
Dinoflagellate photo by Minami Himemiya. Euglenoid photo by Rogelio Moreno.

15. References:
Bhattacharya, D., Yoon, H. S., and Hackett, J. D. (2004).
Photosynthetic eukaryotes unite: endosymbiosis connects the dots.
Bioessays. 26: 50-60.
Chat J., Chalak L., and Petit R. J. (1999). Strict paternal inheritance
of chloroplast DNA and maternal inheritance of mitochondrial DNA
in intraspecific crosses of kiwifruit. Theoretical & Applied Genetics.
99: 314-322.
Emelyanov, V. V. (2001). Rickettsiaceae, Rickettsia-like
endosymbionts, and the origin of mitochondria. Bioscience
Reports. 21: 1-17.
McFadden, G. I. (2001). Primary and secondary endosymbiosis and
the origin of plastids. Journal of Phycology. 37: 951-959.
Yoon, H. S., Hackett, J. D., Ciniglia, C., Pinto, G., and Bhattacharya,
D. (2004). A molecular timeline for the origin of photosynthetic
eukaryotes. Molecular Biology and Evolution. 21: 809-818