some questions about DNA

Discussion in 'Biology & Genetics' started by bardobeing, Nov 15, 2007.

  1. bardobeing Registered Member

    Messages:
    2
    1) Is the entire DNA in every cell necessary?
    2) What happens to DNA levels in organisms through evolution?
    3) Why do amphibians have the most DNA?

    thanks a lot!
     
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  3. pilpaX amateur-science.com Registered Senior Member

    Messages:
    239
    1. well, actually every cell has entire DNA but the DNA is expressed differently depending of tissue. So, basically the entire DNA is not necessary in every cell.

    2. DNA level has no effect on "advancedness" of a organism, most of the plants and corals have more DNA then humans... actually the more parasitic organim is the less DNA it needs to survive.

    3. I dont know
     
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  5. CharonZ Registered Senior Member

    Messages:
    786
    1) also there are specialized cells e.g. mammalian red blood cells that do not contain a nucleus.
    2) it varies according to selective pressures. It can increase as well as decrease
    3) they possibly don't. To my knowledge the largest eukaryotic genome to date is found in protists. Amoeba dubia has been estimated to possess a genome size of ~670 gigabases. However there was an issue that it may be overestimated due to extreme polyploidism.
    As comparison: humans got ~2.9 gigabases Xenopus tropicalis, one of the smaller amphibian genomes ~1.7 gigabases and the largest amphibian genome is that from Necturus lewisi with around 117 gigabases, which just short of the largest genome size within the chordata (130 gigabases) in the lungfish Protopterus aethiopicus.
     
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