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    (Original post by Doughboy)
    I can't believe I skipped this objective!!!

    Explain how genes can be switched on and off by DNA transcription factors including hormones

    Can someone please explain the key points to me? CGP mentioned homeostasis and temperature regulation with genes and Edexcel SNAB Revision guide mentioned drugs and genes!? WTFFF
    I think the main bits are you mention that all the transcription factors must combine in order to form a TIN (Transcription Initation Complex)

    I think there's an example of Thyroxine or something which is involved in regulating temperature?
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    (Original post by koop)
    yh me two I talked about stretch receptors first...and just chemo was mentioned

    just always say x-receptors in the carotid body as they have every type lol
    ...and also always say medulla (both the ventilation centre and the cardiovascular control centre are there) and either sympathetic or parasympathetic nerve! Guarenteed 3 marks at least even if you say the wrong kind of receptor!
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    (Original post by sidrah)
    Just remember that hormones can cause increased production of proteins that can act as transcription factors. Transcription factors form a 'transcription initiation complex' which binds to the promoter region and allows the DNA to be transcribed. Without all the necessary factors, the DNA can't be transcribed. Obviously proteins can also act as repressor molecules, inhibiting transcription. And that's pretty much all you really have to know, there's that tiny bit in CGP about it, but there's no real detail anywhere..
    beat me to it!

    And also, do you have the mark scheme for the Jan 2010 paper
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    (Original post by sidrah)
    Ahem.. Female :p:
    Heroine?!? or superwoman?!? :p:
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    (Original post by thecdon)
    I think the main bits are you mention that all the transcription factors must combine in order to form a TIN (Transcription Initation Complex)

    I think there's an example of Thyroxine or something which is involved in regulating temperature?
    At low body temp:

    Thyroxine binds to thyroid hormone receptor. The thyroid hormone receptor binds to beginning of DNA on gene, and increase the transcription rate. So more protein is made which increases metabolism, therefore producing more heat.
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    (Original post by Doughboy)
    I can't believe I skipped this objective!!!

    Explain how genes can be switched on and off by DNA transcription factors including hormones

    Can someone please explain the key points to me? CGP mentioned homeostasis and temperature regulation with genes and Edexcel SNAB Revision guide mentioned drugs and genes!? WTFFF
    basically referring to how anabolic steroids and erythropoietin switch genes on and off.

    in the case of anabolic steroids, it passes through cell surface membrane, binds with a receptor molecule within the cell and this complex becomes the transcription factor, switches on particular genes that changes the RNA, affecting the types and numbers of proteins produced. somehow linked to the build up of a massively muscular and honed physique.

    erythropoietin, however, binds to receptor ON the cell surface membrane, activating a second messenger in the cytoplasm, triggering a protein kinase cascade (activation of several different proteins). its final product enters the nucleus and acts as a transcription factor, switches on genes linked to protein synthesis of enzymes needed for production of more RBC..

    hope this helped! correct me if i'm wrong, anyone..
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    (Original post by thecdon)
    beat me to it!

    And also, do you have the mark scheme for the Jan 2010 paper
    haha!
    And unfortunately, I was trying to look for one, but its only available online, and needs a teacher login..
    If anyone manages to find it/log in, please let me know..
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    (Original post by jimber)
    Heroine?!? or superwoman?!? :p:
    Either will do.. haha!
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    (Original post by orangeism)
    basically referring to how anabolic steroids and erythropoietin switch genes on and off.

    in the case of anabolic steroids, it passes through cell surface membrane, binds with a receptor molecule within the cell and this complex becomes the transcription factor, switches on particular genes that changes the RNA, affecting the types and numbers of proteins produced. somehow linked to the build up of a massively muscular and honed physique.

    erythropoietin, however, binds to receptor ON the cell surface membrane, activating a second messenger in the cytoplasm, triggering a protein kinase cascade (activation of several different proteins). its final product enters the nucleus and acts as a transcription factor, switches on genes linked to protein synthesis of enzymes needed for production of more RBC..

    hope this helped! correct me if i'm wrong, anyone..


    that just saved my life :yep:
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    I think for the EPO & anabolic steroids we need to know more of the functional effects like increased O2 transport, muscle mass etc.. rather then the mechanisms by which they work
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    Don't know if this has been asked before but do we need to know all the growth factors and what they do : giberellin,cytokinins,ethene and abscisic acid?
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    (Original post by fizzybubble)
    Don't know if this has been asked before but do we need to know all the growth factors and what they do : giberellin,cytokinins,ethene and abscisic acid?

    they're mentioned briefly, but i think we mainly need to know about auxin.
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    (Original post by sidrah)
    haha!
    And unfortunately, I was trying to look for one, but its only available online, and needs a teacher login..
    If anyone manages to find it/log in, please let me know..
    there you go, I think this is the mark scheme you want.
    Attached Images
  1. File Type: pdf 6135_01_msc_20100208.pdf (107.4 KB, 385 views)
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    I have the mark scheme; I'll attach it in a sec when my computer stops dying.

    Edit: never mind, beaten to the punch. For what it's worth, I thought a lot of the questions on that paper were poorly worded and the mark scheme was harsh.
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    (Original post by Doughboy)
    I can't believe I skipped this objective!!!

    Explain how genes can be switched on and off by DNA transcription factors including hormones

    Can someone please explain the key points to me? CGP mentioned homeostasis and temperature regulation with genes and Edexcel SNAB Revision guide mentioned drugs and genes!? WTFFF
    Hey, i was wondering if you could tell me where abouts you posted your summary for the first bit of the article because I can't seem to find it!
    thanks a lot x
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    (Original post by sidrah)
    Here's the Jan 2010 paper from the old spec. I removed my answers, which is why there are some blank spaces.
    Do you have the Mark Scheme for it ?
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    Well I think someone forgot to mention the following(out of the 900+ posts):
    1) Good Luck, try your best (110% is not physically possible :p: )
    2) Just keep thinking to yourself "I am never ever EVER going to look at this ever again" and think of the SNAB books burning

    This kind of helped me going for these past few months
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    (Original post by samydude)
    Do you have the Mark Scheme for it ?
    i just posted the markscheme
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    **** it. I really can't be bothered any more.
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    (Original post by craigp100)
    Well I think someone forgot to mention the following(out of the 900+ posts):
    1) Good Luck, try your best (110% is not physically possible :p: )
    2) Just keep thinking to yourself "I am never ever EVER going to look at this ever again" and think of the SNAB books burning

    This kind of helped me going for these past few months
    :woo:
 
 
 

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