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    ballllllllllllllllllllllllllllll lllllllllllllls
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    OMG..just completely had a mental breakdown tears and everything!!..SOO scared for this exam after the disaster that was jan 2011..seriosuly hope theres more immunity stuff...ive literally just memorised everything i think its probably the only way to do biology, it worked the last two times as i got A's for units 1 and 2 soooo pray it works this time!..
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    half freaking out half not
    i have retaken units 1 and 2
    got B and A
    hopefully my d goes up to at least a high b
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    i dont understand what is meant by short tandem repeats in the introns? anyone help pleaaaaaaaaaaaaase :confused:
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    (Original post by pearlover)
    i dont understand what is meant by short tandem repeats in the introns? anyone help pleaaaaaaaaaaaaase :confused:
    Introns - regions of a gene that do not code for a protein

    Within these introns there are sequences of bases that are repeated several times. These are STRs. The length of the sequences and the times they are repeated vary depending on the individual.

    It is these sequences that are used in DNA profiling

    (from my memory so if I am wrong, feel free to correct me anyone)
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    I just don't understand the immune system part - it's so compliacted. Any adivce on what we exactly need to know?

    Do we need to know the structures of B-cells and T-cells and where they are produced?
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    (Original post by Schoolio93)
    I just don't understand the immune system part - it's so compliacted. Any adivce on what we exactly need to know?

    Do we need to know the structures of B-cells and T-cells and where they are produced?
    It is VERY VERY complex. Since you're a future medic, I've heard immune system is arguably the hardest thing you learn in med school.

    We just need to non-specific responses (inflammation etc etc.) and specific responses (T-cells, B-cells) and role of antigens and antibodies.

    Doubt you need to know structure.
    B-cells basically have antibodies and receptors on their surfaces. T cell have receptors.

    Doubt you need to know this but:
    B-cell produced in bone marrow

    T-cell - produced in bone marrow, but mature in thymus.
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    (Original post by InItToWinItGetIt?)
    Introns - regions of a gene that do not code for a protein

    Within these introns there are sequences of bases that are repeated several times. These are STRs. The length of the sequences and the times they are repeated vary depending on the individual.

    It is these sequences that are used in DNA profiling

    (from my memory so if I am wrong, feel free to correct me anyone)
    thank you so much!
    another question though, is it just the introns then that are used in DNA profiling? what about the exons?
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    (Original post by pearlover)
    thank you so much!
    another question though, is it just the introns then that are used in DNA profiling? what about the exons?
    Exons would be cut out by restriction enzymes. Only introns are used in DNA profiling as the amount of variation of STR's between people is phenomenal.
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    (Original post by pearlover)
    thank you so much!
    another question though, is it just the introns then that are used in DNA profiling? what about the exons?
    I'd be inclined to say no but I'm not sure.

    The reason I would side towards no, is that exons code for proteins and we as humans have largely similar (if not the same) proteins in our bodies, so there wouldn't be much point in looking for similarities as most (if not all) will be similar.
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    (Original post by Schoolio93)
    I just don't understand the immune system part - it's so compliacted. Any adivce on what we exactly need to know?

    Do we need to know the structures of B-cells and T-cells and where they are produced?
    This might help:

    http://www.deberker.com/deberker/Bio...les/Immune.pdf
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    That is a VERY nice way of summarising things. Thanks

    *goes to print it*
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    (Original post by InItToWinItGetIt?)
    I'd be inclined to say no but I'm not sure.

    The reason I would side towards no, is that exons code for proteins and we as humans have largely similar (if not the same) proteins in our bodies, so there wouldn't be much point in looking for similarities as most (if not all) will be similar.

    okai i get it thank you sooo much! u've been helping like everyone on this thread... wish you best of luck and hope u do really well.. m sure u will
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    (Original post by mobius323)
    Exons would be cut out by restriction enzymes. Only introns are used in DNA profiling as the amount of variation of STR's between people is phenomenal.
    thanks soo much! that makes so much sense now! good luck for ur exam
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    (Original post by InItToWinItGetIt?)
    I'd be inclined to say no but I'm not sure.

    The reason I would side towards no, is that exons code for proteins and we as humans have largely similar (if not the same) proteins in our bodies, so there wouldn't be much point in looking for similarities as most (if not all) will be similar.
    They use the introns only, they analyse short tandem repeats which are in the Introns.
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    hey, i just did a past paper and it asked for two examples of plant fibres! and i could have sworn that was unit 2, does that mean we can get asked questions on any unit?
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    (Original post by Telford)
    hey, i just did a past paper and it asked for two examples of plant fibres! and i could have sworn that was unit 2, does that mean we can get asked questions on any unit?
    xylem and schlerenchyma or cellulose - yes we do need to know some stuff from unit 2, but only like 5 marks. So it's all about luck whether you get a q. you know or not.
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    thank you so much!! But isn't the info too simple? What about MHC APC complexes, C4 receptors ???
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    (Original post by pearlover)
    okai i get it thank you sooo much! u've been helping like everyone on this thread... wish you best of luck and hope u do really well.. m sure u will
    Hope so, thanks and same to you

    (Original post by jam277)
    They use the introns only, they analyse short tandem repeats which are in the Introns.
    Cheers

    (Original post by Schoolio93)
    xylem and schlerenchyma or cellulose - yes we do need to know some stuff from unit 2, but only like 5 marks. So it's all about luck whether you get a q. you know or not.
    Do you reckon they could also ask stuff from unit 1?
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    (Original post by Schoolio93)
    thank you so much!! But isn't the info too simple? What about MHC APC complexes, C4 receptors ???
    I have no idea.

    The spec is pretty vague and it just says:

    Non-specific responses of the body to infection
    12 Describe the non-specific responses of the body to infection, including inflammation, lysozyme action, interferon, and phagocytosis.

    The specific immune response
    13 Explain the roles of antigens and antibodies in the body’s immune response including the involvement of plasma cells, macrophages and antigen-presenting cells.

    14 Distinguish between the roles of B cells (including B memory and B effector cells) and T cells (T helper, T killer and T memory cells) in the body’s immune response.
 
 
 
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