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Biology/Endosymbiont Model: mitochondria and chloroplast DNA

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Expert: - 10/24/2010


Question
I understand that mitochondria and chloraplasts both provide energy- I dont undeerstand why they each have their own seperate DNA and are double membraned.Is this because they are the only ones that produce their specific instructions for the cell?  

Answer
Dear Devin,

Mitochondria and chloroplasts are believed to be descended from ancient bacteria that took up residence inside other, larger bacteria.  This is known as the Endsymbiont Model of eukaryotic cell evolution, and you can watch a neat video about it here:

http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter4/animatio...

This is why these organelles have DNA that is circular and similar to bacterial DNA:  they are descended from symbiotic bacteria.

Hope that helps.


Dana

Biology

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Dana Krempels, Ph.D.

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I can answer biology-related questions in the areas of evolution, zoology, botany, genetics, and ecology. But I don't answer homework questions or provide ideas for your science fair projects. So students please do your learning the right way by reading your text assignments and studying!

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At the University of Miami, I teach Evolution and Biodiversity, Botany, Zoology, Genetics, Ecology, and a variety of seminars (e.g., the Biology and Evolution of Human Gender Roles).

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I have a B.S. in Biology and an A.B. in English from the University of Southern California (1980). I earned my Ph.D. in Biology in the area of evolutionary biology/visual physiology from the University of Miami in 1989.

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I am currently an "expert" in both the "Rabbits" and "Wild Animals" categories.

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