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promoter and operon???

Discussion in 'DAT Discussions' started by theedaddy77, May 29, 2008.

  1. theedaddy77

    2+ Year Member

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    HEY SDN!!!
    Im really confused with the difference between operon and promoter and enhancer.. i tired differance sources wiki kaplan.... but im just really confused. My bio teacher sucked so i learned it wrong and badly so if someone could explain the difference ina simple yet detialed way that would be AWESOME!!


    p.s SDN is nice
     
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  3. TeamGuo

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    an operon is a unit of gene expressions that contains one or more related genes which also contains operator and promotor genes.

    So you can think of an operon a chuck of genetic expression.

    So the promotor sequences within an operon is an on/off switch.

    So when you have the promoter region free to do transcription, it's turned on. But if you have a repressor bound to the promoter region, then transcription will not take place, hence off.

    I think enhancer here means region of DNA that can bind activator protein, I am not 100% sure so correct me if I am wrong.

    If activator protein binds to the enhancer sequence and like the word it will enhance/activate transcription to take place. This is a positive regulation.

    Opposite would be using a repressor, negative regulation.

    I would suggest read over the kaplan book again since the gene regulation section can be a little confusing at first.

    Good luck! hope that helped a little. :thumbup:
     
  4. Zerconia2921

    Zerconia2921 Bring your A-game!
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    To add to the post:

    Two systems inducible and repressible.
    Inducible system requires an inducer to allow for transcription. This occurs when the inducer binds to active site on the repressor thereby inducing transcription. If the inducer wasnt present the repressor would bind to the operator and stop transcription.

    Repressible system is different in that you need a co-repressor to stop transcription because without it the lac operon is in a constant state of transcription.

    Oh LAKERS KICK CHITTAR !!!!
     
  5. DRHOYA

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    As said above.......I'll diagram it out for ya.

    Basic strand looks like this (not really, but just imagine)
    This is inducible

    REGULATOR - PROMOTER - OPERATOR - STRUCTURAL GENE
    Repressor RNA polymerase > Repressor X F'ed:thumbdown:
    V ^
    ----->--------->---------->----->----^

    However if an inducer binds to the repressor then you have this (see below)

    REGULATOR - PROMOTER - OPERATOR - STRUCTURAL GENE
    Repressor RNA polymerase > > > > > > >> > > :thumbup:
    V
    Repressor + Inducer = cannot bind to operator.


    Now for the Repressible System
    Normal (see below)

    REGULATOR - PROMOTER - OPERATOR - STRUCTURAL GENE
    Repressor RNA polymerase > > > > > > > > > > > :thumbup:

    Now for the Repressible System
    When it is repressed (see below)

    REGULATOR - PROMOTER - OPERATOR - STRUCTUAL GENE
    Repressor RNA polymerase X F'ed :thumbdown:
    V ^
    Repressor + Corepressor = > > > > > > >

    The repressor + corepressor bind to the operator hindering RNA pol.



    Hope this helps man!

    And yes Zeronica.........MJ is the man, the dunk-contests from his era were amazing. :laugh:
     
  6. theedaddy77

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    u guys were soo helpful. does the enhancer or repressor hit up the promoter or does it hit up the operator. If not then what role does the operator play if the promoter is the on and off switch?

    (btw that dunk was ridiculous!!!!
     
  7. userah

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    operator is what the repressor binds to. in an inducible system, normally the repressor is bound to the operator inhibiting transcription, but if an inducer is present, it will bind to the repressor making it unavailable to bind to the operator. Thus, transcription continues.

    In a repressible system however, transcription is always occurring. The repressor needs a co-repressor (usually the end product of transcription) to become a fully functional repressor molecule. Only then can it bind to the operator and inhibit transcription.

    To put it simply
    Regulator contains the genes for the repressor molecule
    Promoter is where DNA polymerase binds to
    Operator is where the repressor is bound to
    Structural is the actual DNA you're trying to transcribe. It's got all the goodies
     
  8. joonkimdds

    joonkimdds Senior Member
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    operator and promotor overlap each other. But it's better to think that promotor is inside and operator is outside. Depends on what happens to operator, promotor will either do something or nothing.
     

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