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    just a bit confuse with transcription factors, can anyone help?

    from my understanding: peptide hormones attach to a receptor on a cell surface membrane (can't enter as they're polarized), and this activates a secondary messenger which causes a cascade of chemical events which result in transcription factors forming an transpiration initiation complex.

    Steroid hormones enter the cell through the membrane and these attach to inactive transcrition factors which attach to the promotor regions of genes.

    All the transcription factors must be attached with RNA polymerase to the promotor region on the gene in order for it to be expressed and a protein created. This is known as the transcription imitation complex.

    Do Repressor T. factors slow down or stop the transcription? and do these still for the transcription initiation complex?

    Also do we need to know about adenylate cyclase converting ATP into CAMP? and how does this fit in? i know cAMP is a tanscription factor, so is the adenylate cyclase the secondary messenger?
    Please could you correct me if any of this is incorrect i think my knowledge is a bit iffy.
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    There are 3 core practicals for unit 5 right? Respirometer, effect of exercise on tidal volume and breathing rate and habituation.
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    (Original post by amnah_70)
    use this for the article and ull be fine

    Attachment 106734
    you are a god
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    (Original post by Meesta)
    just a bit confuse with transcription factors, can anyone help?

    from my understanding: peptide hormones attach to a receptor on a cell surface membrane (can't enter as they're polarized), and this activates a secondary messenger which causes a cascade of chemical events which result in transcription factors forming an transpiration initiation complex.

    Steroid hormones enter the cell through the membrane and these attach to inactive transcrition factors which attach to the promotor regions of genes.

    All the transcription factors must be attached with RNA polymerase to the promotor region on the gene in order for it to be expressed and a protein created. This is known as the transcription imitation complex.

    Do Repressor T. factors slow down or stop the transcription? and do these still for the transcription initiation complex?

    Also do we need to know about adenylate cyclase converting ATP into CAMP? and how does this fit in? i know cAMP is a tanscription factor, so is the adenylate cyclase the secondary messenger?
    Please could you correct me if any of this is incorrect i think my knowledge is a bit iffy.
    Repressor molecules stop transcription since the transcription initiation complex can't be formed, or it can't bind to the promoter region (depends on the action of the repressor molecule) hence the gene can't be switched on.

    I don't think we need to know about that, I can't even find it in the orange text book and that usually goes beyond what we need to know anyway.
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    I've been using that article, its pretty decent apart from question 24!
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    (Original post by Jammers123)
    Urgghhh...the article (n)
    u mite find this helpful
    54265374-Questions-and-Answers-for-Scientific-Article-June-2011.pdf
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    (Original post by gildartz)
    Repressor molecules stop transcription since the transcription initiation complex can't be formed, or it can't bind to the promoter region (depends on the action of the repressor molecule) hence the gene can't be switched on.

    I don't think we need to know about that, I can't even find it in the orange text book and that usually goes beyond what we need to know anyway.
    ahh okay thanks yeah i saw a few people mention it in this thread so i thought it may come up
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    Hi. :grin:
    Question 3(b)(ii) in the June 2010 paper.
    It asks why when in the respirometer, when all oxygen has been removed and replaced instead with nitrogen.. why there is no movement of the coloured liquid..
    The markscheme says:
    1. no oxygen available/no oxygen uptake ;
    2. reference to anaerobic respiration ;
    3. carbon dioxide produced is absorbed / eq ;
    4. no (net) change of {volume / pressure} of gas ;

    Okay, so I get points 1,2 and 4. But surely if it is anaerobic respiration, no carbon dioxide would be produced anyway? Because in anaerobic, glucose is converted into pyruvate, then lactate. Right? And carbon dioxide is only mentioned as a product from the link reaction onwards, which requires oxygen.
    I just don't get the 3rd marking point.. or is my thinking wrong?
    Thanks to anyone that can clear this up!
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    (Original post by brendan.)
    x
    in anaerobic respiration the glucose molecules are only partly broken so only a part of energy is released and instead of CO2 and H2O, the by-products are either CO2 and ethanol or lactic acid. The equation for this is:
    Glucose -> ethanol + carbon dioxide + energy ( in alcohol fermentation like with yeast?)
    Glucose -> lactic acid + energy ( in mammalian cells)
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    Already got it Thanks anyway
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    Hey quick Q

    hyperpolarisation... inside of the membrane becomes too negative.

    why is this? Too many K+ ions leave the membrane down their concentration gradient?
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    amnah_70 i cant open your link, anyway you could send it to me?
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    (Original post by High As A Kite)
    Hey quick Q

    hyperpolarisation... inside of the membrane becomes too negative.

    why is this? Too many K+ ions leave the membrane down their concentration gradient?
    http://www.interactive-biology.com/1...al-episode-11/

    Try this, the man gets increasingly annoying but his explanation ain't too bad
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    Anyone have any notes on the respiration and spirometer practicals? I don't even remember doing them
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    (Original post by High As A Kite)
    Hey quick Q

    hyperpolarisation... inside of the membrane becomes too negative.

    why is this? Too many K+ ions leave the membrane down their concentration gradient?
    Yes too much K+ has left down their concentration gradient. Also the membrane becomes less permeable to Na+; the sodium channels are closed. The sodium pump continues to pump sodium out. This is what makes it hyper polarised
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    How is the normal resting potential restored after hyper polarisation?
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    June 2010 question paper?
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    (Original post by tkoki1993)
    Yes too much K+ has left down their concentration gradient. Also the membrane becomes less permeable to Na+; the sodium channels are closed. The sodium pump continues to pump sodium out. This is what makes it hyper polarised
    so K+ ions just diffuse back in through K channels down their conc. and electrochemical gradient once more, right?

    thanks btw
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    (Original post by tkoki1993)
    How is the normal resting potential restored after hyper polarisation?
    Through the action of Na/K pumps
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    (Original post by Parthenon93)
    June 2010 question paper?
    It was posted a few pages back
 
 
 

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