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Edexcel A2 Biology SNAB 6BI04 ~ 6BIO5 June 2016 Watch

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    Can anyone help me with the pre release? I dont know how to prepare for it
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    What are transcription factors and promoters and how do they work? Its mentioned a lot in the article. Also the article keeps mentioning genetic 'circuits', does anyone know what is meant by circuits?
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    (Original post by LyreBirds)
    Will we get copy of the prerelease again during the exam or do we need to memorise all the specific parts?
    Yes you get the article in the exam.
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    (Original post by moonandstars)
    Does anyone else feel like as long as you get the jist of the article it's best to just know the all the spec points really well and the article shouldn't really matter as long as you know all the key content ? I don't want to get bogged down these last 2 days reading the article aimlessly when I could be doing the actual content
    That's what i'm doing I think that's a good idea.
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    (Original post by HasanAlam)
    What are transcription factors and promoters and how do they work? Its mentioned a lot in the article. Also the article keeps mentioning genetic 'circuits', does anyone know what is meant by circuits?
    A promoter is a length of DNA required for RNA polymerase to begin transcription of a gene. Can be added when genetically modifying organisms to ensure that the gene that's been inserted is expressed.

    Transcription factors control the transcription of genes. They are proteins that bind to specific sequences of DNA near the starts of genes and increase or decrease the rate of transcription.
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    For the Spirometer practical, the mark scheme always says calibration for volume and calibration for time. What does it mean by that?
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    (Original post by LyreBirds)
    A promoter is a length of DNA required for RNA polymerase to begin transcription of a gene. Can be added when genetically modifying organisms to ensure that the gene that's been inserted is expressed.

    Transcription factors control the transcription of genes. They are proteins that bind to specific sequences of DNA near the starts of genes and increase or decrease the rate of transcription.
    So is it an activator (referred to in cgp) this is confusing me as I don't know if they are the same thing
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    (Original post by B50les)
    So is it an activator (referred to in cgp) this is confusing me as I don't know if they are the same thing
    No, an activator is a transcription factor (so a protein) but a promoter is a sequence on the DNA. Does that make sense?
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    Hey guys does anyone have a typed out document of the core practicals for unit 5 they could either post here or email to me? My notes are rubbish for practicals
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    Hey guys, can someone tell me everything I need to know about GMOs and transcription factors? Thanks
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    (Original post by Kat_b255)
    No, an activator is a transcription factor (so a protein) but a promoter is a sequence on the DNA. Does that make sense?
    Transcription factors can also me hormones! Don't forget the difference between how protein and hormone tfs work
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    Im really strugling to understand what the questions are asking me to do. I write one thing but the mark scheme says another and its really frustrating. Any advice?
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    On page 4 of the scientific article, it says "Protein domains are portions of a protein sequence that can act independently. The domains may influence a protein's functions and characteristics."

    How do they work independently?
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    (Original post by etherealinsanity)
    On page 4 of the scientific article, it says "Protein domains are portions of a protein sequence that can act independently. The domains may influence a protein's functions and characteristics."

    How do they work independently?
    They all have different functions, it's like having multiple different tissues that function together as an organ. For example, in an enzyme, you might have one domain acting as the active site for the substrate but another might be a binding site that induces some certain chemical change in the substrate.
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    (Original post by PhysicsIP2016)
    They all have different functions, it's like having multiple different tissues that function together as an organ. For example, in an enzyme, you might have one domain acting as the active site for the substrate but another might be a binding site that induces some certain chemical change in the substrate.
    Thank you! That really helped, especially with the enzyme example.
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    It's not in the specification, but I just wanted to check. Are we meant to know the detailed structure of the eye (like the choroid, fovea and everything else) are we? I know the structure of the rods we do have to know.
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    Also, I had a question about the rods and action potentials. I'm sorry about all these questions.

    In the green book, it says rods that are exposed to light have their rhodopsin broken down into opsin and retinal. This bleaching means that Na+ channels are closed, but Na+ is still actively pumped out causing the rod cell to enter a state of hyperpolarisation. This hyperpolarisation is a generator potential in the rod which, if large enough to reach the threshold, will allow neurotransmitter substance to enter into the synapse which will stimulate an action potential at the bipolar cell.

    The orange book, however, says that the state of hyperpolarisation in the rod cell means no neurotransmitter (glutamate) is released, and this leads to an action potential occuring in the rod cell.

    I'm confused about the role of the neurotransmitter. The orange book also says neurotransmitter is released when rods are exposed to darkness, which prevents an action potential occuring.
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    (Original post by kdizzle97)
    For the Spirometer practical, the mark scheme always says calibration for volume and calibration for time. What does it mean by that?
    Id like to know this too. Actually I'd like see a model answer to it!
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    (Original post by Browns10)
    That's what i'm doing I think that's a good idea.
    (Original post by moonandstars)
    Does anyone else feel like as long as you get the jist of the article it's best to just know the all the spec points really well and the article shouldn't really matter as long as you know all the key content ? I don't want to get bogged down these last 2 days reading the article aimlessly when I could be doing the actual content
    Are you not preparing for it at all?
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    (Original post by fpmaniac)
    Are you not preparing for it at all?
    prepare by learning the possible spec points you could be assessed on (across unit 1 to 5)
 
 
 
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