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Thread: Can individual genes mix

  1. #1 Can individual genes mix 
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    Can the same identical and individual genes that produce the same outcome combine to provide a mixed or composite result? Thanks


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  3. #2  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    The simple answer is sometimes yes.

    Gene products can be additive, but there are a lot of factors to consider, such as regulation at the pre and post transcriptional stage. There may be a system of negative feedback that would keep the levels relatively the same whether you had lots of copies of the gene or just a few. Then you have things like Lyonization, a shut off of one of the X-chromosomes in Female mammals that prevents these problems.

    Another interesting example of how this can work is in sex determination in Drosophila (flies), the ratio of sex chromosomes to the autosomes determines the sex of the fly, because genes on the autosomes are involved in determining male sex, and genes on the sex X of the sex chromosomes are involved in determining female. Which one wins out depends on how many sets of the gene/chromosomes you have.

    The ratios:
    http://www.ncbi.nlm.nih.gov/books/NB...ort=objectonly
    Detailed explanation of sex determination in flies:
    http://www.ncbi.nlm.nih.gov/books/NBK10025/


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  4. #3  
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    Thanks for the reply and valued advice.

    Can I please further clarify. I noticed you appeared to refer to perhaps 'gene sets', or what combinations of genes can produce. (lingo may be wrong)

    Can I clarify whether the same individual genes can combine. This would be 2 identical genes from the 2 direct parents only.

    Please excuse my lack of knowledge.
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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    If you mean like if Gene A had the sequence ABBA (those letters don't actually refer to anything) and encodes a protein that leads to something like let's say a love for Swedish disco music. And then you had two copies of Gene A combined in a single sequence, like ABBAABBA, would it change the result?

    Well yes it would, but the probability of this happening in an actual genome seems highly improbably, and would likely produce a nonfunctional protein, or it could produce a functional protein that would be different from before. Hypothetically, I suppose it could produce a sorta two-lobed protein, depending on what kind of sequence you have, or if this new bulkier protein could be handled properly by chaperone proteins or how this effects any other of the post-translational modifications.

    Also, in reality a single gene contains regulatory elements and a start and end of the protein coding region. So, genes can't really combine like in the example above.

    Edit: Generally speaking though, any major change to a gene sequence in a protein coding region will change the gene product.
    "I almost went to bed
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    the four white violets
    I put in the button-hole
    of your green sweater

    and how i kissed you then
    and you kissed me
    shy as though I'd
    never been your lover "
    - Leonard Cohen
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    Would you agree this paragraph is correct.? Or should a word or two be changed to clarify.
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    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Quote Originally Posted by speedspeed
    Would you agree this paragraph is correct.? Or should a word or two be changed to clarify.

    An example of this is the extreme matching of a pair of 12hh and 17hh horses over consecutive years. Although breeding from the two identical parents through a number of foals, the height variations can be expected to vary significantly between each foal, as despite individual genes generally only being capable of reproducing themselves, and not of combining with an identical gene for a compromise result, it’s the large pool of genes of the combined parents that each foal draws its individual genes from, which ultimately provides each unique ‘gene set’ and overall variations.

    Thanks for all your help.
    Not really. (It's not necessary to mention how genes are transcribed during DNA replication, or if genes can be combined)

    The height variation you would expect from this pairing would be the result of meiotic recombination and pleiotropy.

    Height is determined by many different genes working in concert (which is called pleiotropy), so many possible assortments of genes are possible.

    Then you have meiotic recombination, which makes sure that every gamete (sperm and egg) from the parents has a different combination of genes from the parent. So each foal will be the result of different genes from the father and different genes from the mother. A variety of possible outcomes will be expected because the height is determined by a large amount of genes. So there simply is a large number of possibilities. There is also the fact that height has a big environmental component, nutrition will effect the height as well, which provides even more chances for diversity.
    "I almost went to bed
    without remembering
    the four white violets
    I put in the button-hole
    of your green sweater

    and how i kissed you then
    and you kissed me
    shy as though I'd
    never been your lover "
    - Leonard Cohen
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  8. #7  
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    i_feel_tiredsleepy

    That is clear now. Thanks for the time taken to answer my queries.
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