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.

What is unique about the structure of mitochondria and

chloroplasts?

Evolution connection: Mitochondria and Plastids

• double membrane

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

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

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.

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.

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

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

Why are mitochondria and chloroplasts so weird?

Evolution connection: Mitochondria and Plastids

Because of their evolutionary history! Both evolved via

endosymbiosis.

Endosymbiosis in a series

1.

Evolution connection: Mitochondria and Plastids

Endosymbiosis in a series

1.

Evolution connection: Mitochondria and Plastids

Endosymbiosis in a series

2.

Evolution connection: Mitochondria and Plastids

Endosymbiosis in a series

2.

Evolution connection: Mitochondria and Plastids

Endosymbiosis in a series

3.

Evolution connection: Mitochondria and Plastids

dinoflagellate

euglenoid

Dinoflagellate photo by Minami Himemiya. Euglenoid photo by Rogelio Moreno.

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