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Thread: Polygenic Inheritance?

  1. #1 Polygenic Inheritance? 
    GDT
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    Hello folks,

    I'm having a tough time understanding the difference between incomplete dominance and polygenic inheritance. When I search on the internet, I keep getting answers like incomplete dominance is a blending of traits, like with a red rose and a white rose becoming a pink rose. Whereas polygenic inheritance is more blending genes like skin color.

    Now...to me these seem like the same things. You're blending genes together. From multiple things comes one thing that shares a blend of characteristics. What am I missing here?

    Thanks!
    GDT


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  3. #2 Re: Polygenic Inheritance? 
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    Quote Originally Posted by GDT
    Hello folks,

    I'm having a tough time understanding the difference between incomplete dominance and polygenic inheritance. When I search on the internet, I keep getting answers like incomplete dominance is a blending of traits, like with a red rose and a white rose becoming a pink rose. Whereas polygenic inheritance is more blending genes like skin color.

    Now...to me these seem like the same things. You're blending genes together. From multiple things comes one thing that shares a blend of characteristics. What am I missing here?

    Thanks!
    GDT
    What is the context?

    Are we assuming DNA cannot be functional in a deteoriated state.

    Polygenic inheritance - a ratio of gene expression, measured from a non-variant source. (measured against selective deteoriation, or gene expression (modification) through "EVOLUTION")


    Incomplete Dominance - does not include genetic deteoriation, or PER SPECIES POLYGENIC INHERITANCE (which include preferential gene expression) EVOLUTION.


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  4. #3  
    Forum Professor Zwirko's Avatar
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    A polygenic trait is one in which there are many genes involved in producing a particular phenotype. Examples would be human skin colour and eye colour. Environmental factors too can have an important influence on the outcome of a polygenic trait. Examples of polygenic phenotypes where the environment plays an important role would be in human intelligence, height and body mass and also in many diseases. Polygenic traits are usually very complicated and poorly understood - geneticists still don't fully understand eye colour yet, for example. Crudely, you can imagine polygenic inheritance as being the addition of many, many co-dominant traits together. Indeed, when researchers look at polygenic traits they often make things easier by narrowing their focus to look at smaller and smaller groups of genes and alleles that are inherited in a more simpler fashion (this why it can sometimes be said that individual "X" has a risk of develping disease "Z").

    Polgenic traits often exhibit a continuous distribution pattern (I think it's a Guassian distribution) like that shown below for height:



    Terms such as incomplete dominance are typically used when dealing with allelic variants of a gene responsible for a specific trait (that is, different variations within the same gene(s) in different individuals). With incomplete dominance there is no smooth blend of phenotypes that can fitted in to a graph like that shown above. In the case of your flowers you've got either red, pink or white - only three possibilities.

    The simple way to remember all this is that one deals with many genes (and the environment) and results in a smooth distribution of phenotypes while the other tends to involve alleles of one or a few genes and results in discrete phenotypes.

    ps

    Ignore what flyingmountains said - I think he/she is one or two sandwiches short of a picnic.
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  5. #4  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Ya, Zwirko is spot on, please ignore flyingmountains post.
    "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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  6. #5  
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    Quote Originally Posted by i_feel_tiredsleepy
    Ya, Zwirko is spot on, please ignore flyingmountains post.
    Ok i think i understand. HUMAN DNA, will become more flexible in the future, along with whatever life remains on this earth, at least for the next few 1000 years. Giving me the conclusion, that another superior DNA structure will eventually result for human dna or structures. Possibly beginning another evolutionarily phase marked by deteoriation and selective gene expression.

    Therefore I'd like to introduce 2 concepts.

    EVOLUTIONARY GENESIS
    EVOLUTIONARY DECLINE/HOMOSTASIS

    I'd like to point out that when genetic material is building and bonding, to accomodate its environment, its a GENESIS. This building and bonding of genetic material has not been observable in modern science, although it is a phase of EVOLUTION.

    Evolutionary DECLINE, is what modern science has been observing. Genetic material is not "building" or "bonding" to form more resistance structures. It is simply expressing different "POLYGENIC TRAITS", in response to environmental conditions or reaction. I think "incomplete dominance", may be an evolutionary response to genetic deteoriation. Ensuring different traits are expressed routinely limiting the eventual exclusion of traits. I think earthly genetic material has stablized itself, in absence of said variables which induce rapid genetic building and bonding. GENESIS.

    2 INEVITABLE TRUTHS

    1. Mankind all of mankind left alive, their genetic material will be bonded and build according to a set of instructions. (THIS IS NOT EVOLUTION - LOCUST). We can assume, that said radiation, will ensure for the next few generations that this genetic material continues to build and bond, although according to stimulus, EVOLUTION.

    2. We can assume, that at some point in time, the variable influencing EVOLUTION, by creating bonds, and building genetic structures, will either be unable to reach a more stable genetic HOMOSTASIS, or the variable will be removed all-together (most likely both situations). Will end. And the existing DNA, will gradually express more traits which are used more frequently, generationally. And less used traits will gradually become less dominant and deteorate.

    3. Mankind should at this point in time, be able to influend EVOLUTION by the addition of new genetic information directly. (or possibly succumb to a slow generational death)

    Since science has never observed the conditions necessary for new bonds and genetic information to adapt itself into DNA, through rapid success, and rapidly in a SPECIES. Its impossible for SCIENCE TO CONCLUDE that EVOLUTION is the BUILDING OF DNA, AND THE DETEORIATION OF DNA

    1. MODERN EVOLUTION - does not view deteoriation of DNA as EVOLUTION

    2. MODERN EVOLUTION - has not observed true adaptations in DNA resulting in new genetic formations, rather science has been observing dna in a state of HOMOSTASIS.


    THIS WILL ALL CHANGE - BUT I'VE BEEN EXCITED - EVER SINCE CHRISTS'S TOLD ME THOSE 3 ETHNIC GROUPS, WHICH HAVE MADE ME SUFFER GREATLY AND ALSO MANKIND - WILL BE PUT TO DEATH - AND THE REST OF THE TARGETS.

    OKAY OKAY, well I don't expect any of you to believe me, is science limited by OBSERVATION? Or because you had not observed these things, and have no evidence to rule them out, WHY PERVERT SCIENCE?
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  7. #6  
    Moderator Moderator TheBiologista's Avatar
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    flyingmountains- if you continue to use other peoples threads to push your ideas, your posting rights will be suspended.
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  8. #7  
    GDT
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    Zwirko thanks very much. I appreciate it getting cleared up.

    GDT
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  9. #8  
    New Member Dory's Avatar
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    Quote Originally Posted by Zwirko
    A polygenic trait is one in which there are many genes involved in producing a particular phenotype. Examples would be human skin colour and eye colour. Environmental factors too can have an important influence on the outcome of a polygenic trait. Examples of polygenic phenotypes where the environment plays an important role would be in human intelligence, height and body mass and also in many diseases. Polygenic traits are usually very complicated and poorly understood - geneticists still don't fully understand eye colour yet, for example. Crudely, you can imagine polygenic inheritance as being the addition of many, many co-dominant traits together. Indeed, when researchers look at polygenic traits they often make things easier by narrowing their focus to look at smaller and smaller groups of genes and alleles that are inherited in a more simpler fashion (this why it can sometimes be said that individual "X" has a risk of develping disease "Z").

    Polgenic traits often exhibit a continuous distribution pattern (I think it's a Guassian distribution) like that shown below for height:



    Terms such as incomplete dominance are typically used when dealing with allelic variants of a gene responsible for a specific trait (that is, different variations within the same gene(s) in different individuals). With incomplete dominance there is no smooth blend of phenotypes that can fitted in to a graph like that shown above. In the case of your flowers you've got either red, pink or white - only three possibilities.

    The simple way to remember all this is that one deals with many genes (and the environment) and results in a smooth distribution of phenotypes while the other tends to involve alleles of one or a few genes and results in discrete phenotypes.

    ps

    Ignore what flyingmountains said - I think he/she is one or two sandwiches short of a picnic.
    Beautiful explanation.
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