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View Poll Results: Where did the mitochondria and chloroplasts come from?

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  • Prokaryotic organisms creating symbiotic relationship with eukaryotic organsims.

    13 86.67%
  • Eukaryotes built these organelles from scratch.

    2 13.33%
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Thread: Origin of mitochondria/chloroplasts

  1. #1 Origin of mitochondria/chloroplasts 
    墨子 DaBOB's Avatar
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    There are two hypothesis as to where these two oranelles (mitochondria and chloroplast) came from.

    1. They were originally prokaryotes that were engolfed by a eukaryote. Or, they were parasitic prokaryotes that developed a symbiotic relasionship with a eukaryotes. Either way they were prokaryotic organisms that joined eukaryotic ones.

    2. The organelles were developed inside the eukaryote as a part of evolution.

    Personally I see very little evidence for answer 2. I hope that you all explain your answers. If you pick number 1 but, have ideas as to why people believe 2 to be correct than please explain those too. That is the main reason I ask.


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  3. #2  
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    Interestingly, a fellow named Walter Gehring recently proposed something similar for the evolution of eyes. Have a look for his papers and anything to do with the "Russian Doll Model" of eye evolution. He has also done some work with the Pax6 gene. If you remember in the news a while ago, some scientists produced fruit flies with eyes over their body... that's mainly the responsibility of the Pax6 gene.


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  4. #3  
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    Let's not forget mitochondria and chloroplasts both have their own separate DNA and they are capable of replicating on their own.
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  5. #4  
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    creating something from scratch isnt evolutions way, it only modify what it already have
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  6. #5  
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    I believe that they may have been built from scratch. Maybe life arose on the planet more than once and mitochondria and chloroplasts may be the living proof of that.
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  7. #6  
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    I believe that they may have been built from scratch. Maybe life arose on the planet more than once and mitochondria and chloroplasts may be the living proof of that. .
    thats just silly, once life arose on a planet the chance for such things to happen again is infinitly small. Chroloplasts and mithocondria is the proof of symbios theory
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

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  8. #7  
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    We were just talking about this a while ago in my Bio class. The professor explained to us the early prokaryote theory which I found was very interesting. I didn't know there was an opposing view of that. So if they were created by eukaryotes what is the story. How were these eukaryotes powered before the mitochondria evolved. Also zelos made a good point, from what did they evolve. Why do only those particular organelles have their own DNA, ribosomes, and ability to replicate. I would be interested to hear the other story. Until then the evidence I have seen leads me to the prokaryote theory.
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  9. #8  
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    Eukaryotes exsited for a while before gaining any mitochondria or chloroplasts. Using endocytosis and things like that. Obviously it would be advantageous to be able to harness sunlight or Oxygen to prouce energy. This would be why the eukaryote might creat such an organelle. It has been suggested that a cell membrane engulfed a plasmid (small bit of DNA) and that is why they have there own DNA.

    This is all I know about that theory and it has so many holes. The mitochondria and plastids are the wrong size to have been plasmids. There are bacteria that are very similar to the mitochondria and plastids. I could go on. I posted this in hopes that someone could give more evidence for answer 2. Because, like the rest of you seem to agree on, it just doesn't seem to make sense.
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  10. #9  
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    Quote Originally Posted by VMStudent
    I believe that they may have been built from scratch. Maybe life arose on the planet more than once and mitochondria and chloroplasts may be the living proof of that.
    Have you heard of Ocklam's razor (The Law of Parsimony): "A rule in science and philosophy stating that entities should not be multiplied needlessly. This rule is interpreted to mean that the simplest of two or more competing theories is preferable and that an explanation for unknown phenomena should first be attempted in terms of what is already known".

    http://www.thefreedictionary.com/Ockham%27s%20razor

    I'm not one to just shoot down a theory and say there is no possible way but, I must agree that it is much less likely to have evolved on it's own.
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  11. #10  
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    1. They were originally prokaryotes that were engolfed by a eukaryote. Or, they were parasitic prokaryotes that developed a symbiotic relasionship with a eukaryotes. Either way they were prokaryotic organisms that joined eukaryotic ones.

    2. The organelles were developed inside the eukaryote as a part of evolution.
    Neither?

    It is very clear, with the results of genomic studies, that the current mitochondria has evolved from an ancient alpha-proteobacteria. Among the scientific community that isn't really debated. Like ... at all. For the last 9 years or so.

    Also there is really no evidence to show that a true eukaryote exists or ever existed without a mitochondria.

    The best hypothesis is that the host was an Archaebacteria that was strictly dependent on H2 as an energy source and CO2 as a carbon source and that the symbiont was a facultative anaerobic alpha-proteobacteria. This supports a syntrophic mechanism for the driving forces behind the selection for mitochondria.

    For me, what complicates the matter is that there is no existing bacteria that exports ATP through its cell membrane (which is something mitochondria do). I suppose that might be evidence for the mitochondria evolving from the cell on its own .... but not really.
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  12. #11  
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    Quote Originally Posted by Zelos
    I believe that they may have been built from scratch. Maybe life arose on the planet more than once and mitochondria and chloroplasts may be the living proof of that. .
    thats just silly, once life arose on a planet the chance for such things to happen again is infinitly small. Chroloplasts and mithocondria is the proof of symbios theory
    Yes, I know I've always been a good biology student. But I tend to try to excape everyone's way of thinking and explore new prespectives.

    I'm completely aware of the symbios theory (:
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  13. #12  
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    ???

    So, can we define single cells from a multicellular organism as an organism themselves then?

    or is a cell still a part from a whole...
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  14. #13  
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    Quote Originally Posted by Zwolver
    ???

    So, can we define single cells from a multicellular organism as an organism themselves then?

    or is a cell still a part from a whole...
    My answer would be that everything is a part and the whole at the same time. The yin yang principle. There cannot be one without the other.
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  15. #14  
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    My answer would be that everything is a part and the whole at the same time. The
    hippie?

    you/it are either a part of something greater or you/it are the greater.
    You cant be the whole and a part it doesnt make sense but you can have smaller parts but you arent then the complete whole
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

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  16. #15  
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    Although it will always remain a hypothesis (like everything in science) there is currently no doubt among biologists in that both organelles have endosymbiotic origin from bacteria. Evidence is overwhelming and the alternative hypothesis does not resist the simplest trial. The endosymbiotic origin can (in practice) be considered as a fact.

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  17. #16  
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    Prokaryotic organisms creating symbiotic relationship with eukaryotic organsims thats RIGHT


    We know that the eukayots are created from prokaryots there are two opinions
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  18. #17  
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    In NASA's Astrobiology Magazine there is a series of interviews with Lynn Margulis who wrote a fine book "Microcosmos: Four Billion Years of Microbial Evolution". She would like to include one more symbiont to the mix: Spirochetes, which she theorizes evolved into cilia. In any event, here is the part of the interview that has the most bearing on the subject at hand.

    http://tinyurl.com/eglok
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