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    (Original post by Waqar Y)
    Allrighty, let's start with the first bit then:

    First, you've gotta get the section of the genome you want - that is the gene you want from which part of the chromosome.
    To do this you can, extract the part of the genome you want by breaking it off the chromosome, this is known as a shotgun approach.

    Then, you've got a lot of genome present, so you put it into BAC (bacterial artificial chromosome) and you insert that BAC into E.coli

    E.coli then reproduces, and you end up with loads of copies of the genome.

    You then use restriction enzymes to cut it into fragments, this gives overlapping fragments because you've got loads of sections of the genome which have been cut at different places.

    You then mix the fragment types with DNA polymerase and free DNA nucleotides and primers(which are short strands of DNA that bind to the 3' end of DNA)
    AND ALSO Terminator bases, which have one of four colours (As there's only 4 possible bases A T C G)

    The primer binds/anneals to the 3' End of DNA - this allows DNA polymerase to get working and adds the free nucleotides to the fragment.

    So, when the terminator base is added and binds to the DNA fragment, it throws off the enzyme DNA polymerase, so DNA replication is stopped.

    Therefore, different fragments will be thrown off at different points, and will have one of four colors ( A could be red, T could be green, C could be yellow and G could be black) - These are fluorescent labeled and you'll see why they're useful later on.

    - So now you've got different fragment lengths of your genome, that has been stopped at different points for each fragment.

    you then separate using electrophoresis, it involved cutting a well on a slab of agar, electric current is passed through the DNA fragments that you place in the well.
    DNA is negatively charged cus of the phosphoryl groups, so it'll move to the positive end.

    Shorter DNA fragments will pass through quicker through the gel, so you'll end up with fragments on this gel that are separated by size.

    They'll pass through an automated sequencer at the end of the gel, and the flourcent label will be used by this automated sequencer to give the colour of that fragment, therefore the bases to.
    Thanks a lot, that makes things a lot clearer. It's annoying how in the ocr spec, this is the first bullet point but in order to really understand it, you need to understand the rest of the topic first.
    Thank you for taking the time to break it down for me
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    anyone got the january f215 paper and mark scheme?
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    I actually dont get anything neither can I build up the courage to remember anything! can someone please make sense of Meiosis 1 and meiosis 2 pleeeeease
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    can someone explain a part of the polymerase chain reaction to me please?

    in the book it says that the double stranded section of DNA only grows from the 3' end
    What does 3' and 5' end mean?
    please quote, thanks
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    (Original post by wilsea05)
    can someone explain a part of the polymerase chain reaction to me please?

    in the book it says that the double stranded section of DNA only grows from the 3' end
    What does 3' and 5' end mean?
    please quote, thanks
    PCR is a way of amplify DNA (increase the sample size)


    1. Heat DNA to 95oC to separate strands as the hydrogen bonds break between the complementary bases
    2. Add primers (short bits of DNA for DNA polymerase to bind to)
    3. Reduce temp to 55oC; primers anneal (bind to complementary bases)
    4. Raise temp to 72oC and add DNA polymerase
    5. DNA polymerase binds and makes new complementary DNA using free nucleotides
    6. Repeat the process to increase DNA exponentially

    Hope this helps! Do you remember from AS that the bases bond with condensation reactions with each other? 3' means that the bond is on carbon 3 of a single base molecule, and 5' at on carbon 5
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    People have been revising since march!?!? I thought I was being well prepared by starting in easter!
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    Ha, revision this early, never mind in march!!!!

    Im pretty sure i can fail this exam (can get 32%) to get a B, which is all i need. So sorry to say guys, but revision can wait for a few weeks ...

    Also, just a tip, while reading through the material, its easy to connect the stuff to things we have covered in other modules, try and do this as it is a synoptic paper, and you could start to think of questions that involve both synoptic and normal material
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    (Original post by Falcon91)
    Hai Iby! hows it goin (if you remember me :P)

    Also for you guys...

    Module 4 Notes that I made last year (hopefully not much/nothings changed in that content).

    http://www.mediafire.com/file/qit5iz...io%20notes.doc

    good luck, hope you nail these exams
    hay your notes really helped, can u please upload notes for the other modules.
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    (Original post by Waqar Y)
    Allrighty, let's start with the first bit then:

    First, you've gotta get the section of the genome you want - that is the gene you want from which part of the chromosome.
    To do this you can, extract the part of the genome you want by breaking it off the chromosome, this is known as a shotgun approach.

    Then, you've got a lot of genome present, so you put it into BAC (bacterial artificial chromosome) and you insert that BAC into E.coli

    E.coli then reproduces, and you end up with loads of copies of the genome.

    You then use restriction enzymes to cut it into fragments, this gives overlapping fragments because you've got loads of sections of the genome which have been cut at different places.

    You then mix the fragment types with DNA polymerase and free DNA nucleotides and primers(which are short strands of DNA that bind to the 3' end of DNA)
    AND ALSO Terminator bases, which have one of four colours (As there's only 4 possible bases A T C G)

    The primer binds/anneals to the 3' End of DNA - this allows DNA polymerase to get working and adds the free nucleotides to the fragment.

    So, when the terminator base is added and binds to the DNA fragment, it throws off the enzyme DNA polymerase, so DNA replication is stopped.

    Therefore, different fragments will be thrown off at different points, and will have one of four colors ( A could be red, T could be green, C could be yellow and G could be black) - These are fluorescent labeled and you'll see why they're useful later on.

    - So now you've got different fragment lengths of your genome, that has been stopped at different points for each fragment.

    you then separate using electrophoresis, it involved cutting a well on a slab of agar, electric current is passed through the DNA fragments that you place in the well.
    DNA is negatively charged cus of the phosphoryl groups, so it'll move to the positive end.

    Shorter DNA fragments will pass through quicker through the gel, so you'll end up with fragments on this gel that are separated by size.

    They'll pass through an automated sequencer at the end of the gel, and the flourcent label will be used by this automated sequencer to give the colour of that fragment, therefore the bases to.
    Hay, whats with the overlapping bit in genome sequencing, that really confuses me????????
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    (Original post by sportycricketer)
    PCR is a way of amplify DNA (increase the sample size)


    1. Heat DNA to 95oC to separate strands as the hydrogen bonds break between the complementary bases
    2. Add primers (short bits of DNA for DNA polymerase to bind to)
    3. Reduce temp to 55oC; primers anneal (bind to complementary bases)
    4. Raise temp to 72oC and add DNA polymerase
    5. DNA polymerase binds and makes new complementary DNA using free nucleotides
    6. Repeat the process to increase DNA exponentially

    Hope this helps! Do you remember from AS that the bases bond with condensation reactions with each other? 3' means that the bond is on carbon 3 of a single base molecule, and 5' at on carbon 5
    thanks, only the last bit of that was really necessary though lol
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    (Original post by nif1boy)
    Hay, whats with the overlapping bit in genome sequencing, that really confuses me????????
    because you've got more then one copy of the genome, when you use restriction enzymes to cut the fragments up - you'll end up with overlapping fragment sizes.
    using electrophoresis> you'd be able to seperate these fragments in order of size and place them in an automated sequencer, where they can be read and used to determine the base sequence. the computer program will automatically know if there are overlapping fragments, and it will only be scanned in once.
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    How far are you guys into revision?
    I am moving onto Ecosystems, and should go straight to module 4 in the next 1-2 weeks...
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    has anyone finished revising this unit yet?
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    (Original post by J DOT A)
    How far are you guys into revision?
    I am moving onto Ecosystems, and should go straight to module 4 in the next 1-2 weeks...
    :ditto:

    try and do eco systems within a week
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    (Original post by Deyn_08)
    :ditto:

    try and do eco systems within a week
    What so your on Ecoysystems also?
    I need to do that/ finish module 4, and then revrevise everything:/ Hopefully there is enough time.
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    (Original post by J DOT A)
    What so your on Ecoysystems also?
    I need to do that/ finish module 4, and then revrevise everything:/ Hopefully there is enough time.
    there will be, i'm re revising stuff now

    did lac operon today
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    (Original post by J DOT A)
    What so your on Ecoysystems also?
    I need to do that/ finish module 4, and then revrevise everything:/ Hopefully there is enough time.
    lol mate vast majority of people haven't started revising at all. and there's still 5 weeks until the exam...
    what grade are you aiming for/predicted?
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    Help anyone got any revision notes they want to share? xxxx
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    (Original post by flowermaster91)
    That was so cool.


    In another news DOES ANYONE HAVE THE JANUARY 2011 EXAM? I NEED MORE PRACTICE!!!

    Scratch that I found it! WOOOOOOW!
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    Finished the whole thing yesterday, back to going over it slowly slowly..
 
 
 
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