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Organisms evolve through gene regulation: who/what is the regulator?

  1. May 13, 2007 #1
    Who or what regulates genes?
    And does this falsify the view that random mutation (and selection) evolves organisms?
     
  2. jcsd
  3. May 13, 2007 #2
    Genes regulate genes. No, this does not falsify arbitrary mutations and/or natural selection.
     
  4. May 13, 2007 #3
    Protein coding genes are often regulated by non-coding DNA sequences. These sequences are not transcribed. An example of a regulatory sequence would be a promoter, a site where proteins that aid in the transcription of a coding gene can bind prior to the actual act of transcription. Another regulatory sequence might sit between the promoter and the coding gene, to which a repressor protein might bind. The repressor protein gets in the way of transcription proteins bound to the promoter, so the coding gene can't be transcribed. These are simple examples; there are many types of regulatory sequences throughout the genome of an organism.
     
  5. May 14, 2007 #4
    So there are different regulatory sequences, which are affected by biological and environmental influences and cause evolution (?).

    Doesnt this directly contradict the view that: a random mutation occurs and (over time) causes evolution?
     
  6. May 14, 2007 #5
    Not at all. Random mutations can occur in the regulatory sequences too. I think the point here is that evolution of regulatory sequences can potentially have a greater effect than evolution of coding sequences, because many regulatory sequences work with multiple coding sequences. However, whichever type of sequence you have, the ultimate end product is eventually a protein (or lack thereof), upon which natural selection can act.
     
  7. May 14, 2007 #6
    They both occur and both effect evolution along with gene duplications, alternative splicing, etc. etc.
     
  8. May 17, 2007 #7
    The point is not that that could also happen and evolve organisms. The point is that that could also not happen, and still evolve organisms (through higher order gene regulation).

    Take these statements for example:

    Since epigenetics are "changes in gene function that occur without a change in the DNA sequence", the above link states, simply put, that there are mechanisms in those plants which are not controlled by gene mutations, yet do rearrange the genome. Basically, the plants detect environmental conditions that are unfavorable and then modify and reorganize specific parts of their genome in order to generate variations.
     
    Last edited: May 17, 2007
  9. May 17, 2007 #8
    Changes in gene function due to epigenetics are still "genetic" in origin. Usually people refer to epigenetic regulation as any of the various chromosomal modifications that occur and can make transcription of certain genes more or less likely. The factors that affect these chromosomal modifications are themselves proteins coded for by DNA. So epigenetic regulators are just as subject to mutation as any other genes.
     
  10. May 17, 2007 #9
    Perhaps even more so in many cases, as many essential genes to an organism's "fitness" become conserved and their exons are less subject to mutation than other regions of the genome.
     
  11. May 18, 2007 #10
    Also, rearrangement alone has the potential to powerfully effect transcription levels. Many regulators function via their position in relation to the genes they regulate. This is in addition to the fact that, as Cinncinnatus wonderfully put it, mutations can still be at the root of epigenetic regulator evolution.
     
  12. May 23, 2007 #11
    Just FYI, but this week's Nature has a whole section of articles covering the topic of epigenetics.....assuming one has access.

    Nature 24 May 2007 Volume 447 Number 7143

    Epigenetics p395
    Alex Eccleston et al.

    Perceptions of epigenetics p396
    Adrian Bird

    Transcription and RNA interference in the formation of heterochromatin p399
    Shiv I. S. Grewal and Sarah C. R. Elgin

    The complex language of chromatin regulation during transcription p407
    Shelley L. Berger

    Nuclear organization of the genome and the potential for gene regulation p413
    Peter Fraser and Wendy Bickmore

    Epigenetic inheritance in plants p418
    Ian R. Henderson and Steven E. Jacobsen

    Stability and flexibility of epigenetic gene regulation in mammalian development p425
    Wolf Reik

    Phenotypic plasticity and the epigenetics of human disease p433
    Andrew P. Feinberg
     
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