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AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011 watch

  • View Poll Results: Are you resitting this unit?
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    (Original post by rrelish)
    Transforming a bacteria is basically inserting a new gene into it, usually via a plasmid.
    To get the desired gene into the plasmid in the first place, both are cut using the same restriction endonuclease enzymes. This means they will both have complementary "sticky ends" and so can be joined exactly by DNA ligase.
    The plasmid then has to be put into the bacteria:
    It is warmed and in the presence of Ca2+ ions the permeability of the cell membrane of the bacteria increase so the plasmid is taken up
    BUT:
    - Only as few as 1% of bacteria take up the plasmid and
    - even if they do take it up, the plasmid may not have incorporated the desired gene in the first place, it may have closed up.

    1) Use antibiotic to find out which ones took up the plasmid (with and without the new gene)
    Say Plasmid has 2 anti biotic resistance genes a and b, and we put the new gene we want in place of b.
    - Grow all the bacteria on a medium of antibiotic A, to find out which bacteria took up the plasmid. The ones that survive have got the plasmid :clap2:

    (We dont use antibiotic B becuase the transformed bacteria would die also, and we wouldnt know which one it was)

    Antibiotic resistance markers:
    - So now you've got the bacteria with the plasmids, how to tell if the plasmids have the new gene or not?
    - Grow on a agar plate, to develop into separate colonies
    - transfer each colony onto a 2nd (replica plate) in the exact same position as they were on the 1st. This plate has the antibiotic B on it.
    - The bacteria that that die on this will have the NEW gene, on the plasmid in them. (because this gene was replaced in the first place, and so bacteria is not resistant against it anymore)

    Finally, match the place the bacteria is missing from the 1st plate, and those are your transformed bacteria You can they grow them on a large scale.
    E.g insulin

    There are enzyme and fluorescent marker too

    I got carried away there but hope that helps!
    Thank you This is amazing
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    has anyone got any examples of synoptic essays/ synoptic essay plans they could pretty please post?
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    Do we have to know about the CFTR and cystic fibrosis in gene therapy? Its not in the spec but theres a whole chapter on it in the book...? i dont wanna be learning something we dont have to know!! thanks
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    Why rods have low visual acuity:
    -Many rod cells share a single bipolar neurone. When the combined generator potentials is sufficient to exceed threshold value, only a single impulse is sent no matter how many rods are stimulated.

    Am I correct

    In the book though, it says 'only single impulse sent no matter how many neurones are stimulated
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    im not looking forward for the essay q.
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    What do we need to know about Phosphocreatine ?
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    (Original post by Mazii)
    What do we need to know about Phosphocreatine ?
    I think just that it allows muscles to regenerate ATP without respiring? Not too sure on that one though, so sorry if I'm wrong!
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    (Original post by Flux_Pav)
    yeah!
    lets hope they don't ask us what happens when pH rises ..
    Yeah, fingers crossed! I don't think they should unless they give us a massive chunk of reading beforehand from which we get the answer because it's not covered in the specification. But then again this is AQA, and we know how well they follow the spec -___-
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    (Original post by Libertiney)
    I think just that it allows muscles to regenerate ATP without respiring? Not too sure on that one though, so sorry if I'm wrong!
    I think that's proberly it then; cus I couldn't find much in the textbook about it either
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    (Original post by Mazii)
    What do we need to know about Phosphocreatine ?
    During muscle contraction you need lots of ATP right? for energy.
    ATP can come from respiration but this requires o2 and its used up quickly when you're exercising.
    ATP is need in muscle contraction - for the active transport of Ca2+ back into sarcoplasmic reticulum and also the movement of the myosin head.

    Phosphocreatine is used to generate ATP anaerobically
    - its a reserve supply of Pi and so is available immediately to combine with
    Pi+ ADP ---> ATP
    The Pi is then replenished using Pi from ATP when the muscle is relaxed.

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    A synoptic essay title from June 05 was 'Bacteria affect the lives of humans and organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of humans and other organisms'

    Can anybody think of any ideas for this? I can only think of genetic variation causing antibiotic resistance.
    Thanks!
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    (Original post by Nat1986)
    A synoptic essay title from June 05 was 'Bacteria affect the lives of humans and organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of humans and other organisms'

    Can anybody think of any ideas for this? I can only think of genetic variation causing antibiotic resistance.
    Thanks!
    Nitrogen and carbon cycle
    DNA technology - e.g making insulin
    Cheese flavour?
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    (Original post by rrelish)
    Nitrogen and carbon cycle
    DNA technology - e.g making insulin
    Cheese flavour?
    Thank you...I did think after about the sabrobiotic microoganisms. I think thats a hard essay title!
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    i wish that the essay question is an easy one
    something like
    how do organisms increase chances of survival
    if theres 2 essyas on genetics il probs start crying
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    (Original post by hahaff)
    i wish that the essay question is an easy one
    something like
    how do organisms increase chances of survival
    if theres 2 essyas on genetics il probs start crying
    AGREED! I hate genetics, bleh. Really really hope that they don't give us one that's basically just AS biology like last year's disease essay! I would absolutely love an enzymes essay!
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    (Original post by Jing_jing)
    AGREED! I hate genetics, bleh. Really really hope that they don't give us one that's basically just AS biology like last year's disease essay! I would absolutely love an enzymes essay!


    yes an enzyme essay wud be brilliant
    i cant wait for this exam to be over tbh need to revise for my chem5 exam 2 days later

    why does aqa always put the bio exams 2 days before the chemistry exams
    hoping that the bio5 is like the bio4 exam hardly any hsw
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    (Original post by vickidougal)
    ohmygolly, that panicked me for a minute. i cant believe they would do that! was just about to rewrite all my notes on nerve impulses so thanks for telling me haha
    loool i knowww i did too
    i know its a probably been said..but stupid aqa
    btw how are you revising for the essay?
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    (Original post by hahaff)
    [/B]

    yes an enzyme essay wud be brilliant
    i cant wait for this exam to be over tbh need to revise for my chem5 exam 2 days later

    why does aqa always put the bio exams 2 days before the chemistry exams
    hoping that the bio5 is like the bio4 exam hardly any hsw
    Yeah, I can't wait till this one is over either, I have M2 on the same day, and M3 an STEP on Monday, and then STEP after the biology exam.

    Because AQA are sadists, discontent with merely setting hard questions, they've made it their mission to mess up people's revision timetables too
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    does anyone knows where i can find the specimen question paper for this unit, excluding the aqa website? everytime i try to download it or even just open the pdf file it gives me error :/ thanks!
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    (Original post by Nat1986)
    A synoptic essay title from June 05 was 'Bacteria affect the lives of humans and organisms in many ways. Apart from causing disease, describe how bacteria may affect the lives of humans and other organisms'

    Can anybody think of any ideas for this? I can only think of genetic variation causing antibiotic resistance.
    Thanks!
    like...dna technology, bacteria involved in nitrogen and carbon cycle, producing antibiotics, enzymes and hormones.
 
 
 
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