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    (Original post by sportycricketer)
    If you want me to work it out, PM me your module UMS and what you got in your practical /40 this year and I can tell you
    Can you convert raw marks from the practical into UMS? I thought they changed that every year :eek: Please could you tell me what 34/40 would be?
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    centrioles play a vital role in both mitosis and meiosis and for both processes have almost identical function. During Prophase 1, the centrioles begin to migrate to opposite poles and also begin to produce spindle fibres. During metaphase 1, the centrioles are at opposite poles and attach the spindle fibres to the centromeres of the chromosomes, this is where random assortment of chromosomes occurs. During anaphase 2, the spindle fibres shorten and the homologous pairs are pulled to opposite poles.

    for meiosis 2, the spindle fibres do exactly the same thing except for one crucial difference, the sister chromatids are pulled apart during anaphase 2 as opposed to anaphase 1 where entire chromosomes were pulled apart. Other than that the functions during the same stages are exactly the same. Hope this helps a little.
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    Can someone please help explain what exactly we need to know about artifical selection of wheat?
    Thanks
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    (Original post by heartskippedabeat)
    Can you convert raw marks from the practical into UMS? I thought they changed that every year :eek: Please could you tell me what 34/40 would be?
    34/40 is usually the mark for an A so 80% therefore 48/60 ums
    Hope i helped!
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    (Original post by merrmerr)
    34/40 is usually the mark for an A so 80% therefore 48/60 ums
    Hope i helped!
    yeah you're right
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    (Original post by fortunecookie)
    Ahh I see, that makes sense. I guess you'd have to do PCR a LOT in order to replicate it, so a lot of effort.

    Yeah, was just trying to get my head around it. Because in the 'outline DNA sequencing' it had the use of BAC's. So when is PCR used? Replicating DNA when searching for genetic diseases? I hate all this stuff!
    Lol i know wot u mean every1 has somehting they hate and cant get in unit 5 (for me its some of the genetics)

    PCR is basically the copying the DNA sample. Ill beak it down into points:
    1. DNA molecule is mixed with DNA polymerase (Taq polymerase), primers and free dna nucleotides.
    2. the mixture is heated (to 95degrees), breaking the hydrogen bonds between the DNA molecule, thus we are left with two DNA single strands.
    3. the heat is bought down to 60 degrees, enables primers to now bind (anneal) to its complementary sequence on a specific part of the strands. this forms double strands on part of the dna single-strand.
    4. the heat is bought upto 75degrees, now the Taq polymerase (special as it is able to work in high temps) can now bind to double strands on the DNA strand and use free dna nucleotides to continue the double strand.
    5. thus we are left with two DNA double strands which are identical to the original DNA molecule we started with.
    6. This process can be repeated with these two new DNA molecules, thus we get 4 DNA molecules after the 2nd cycle, repeat PCR for these 4 we get 8 etc.

    Thats PCR, now Genome Sequencing is:
    1. sample of dna is denatured to reveal two DNA single strands.
    2. these are then mixed with DNA polymerase, free NTPs (nuleoside triphosphate), ddNTP (dedioxynucleoside triphostphate) and primers.
    3. primers anneal to the dna strands via specific complementary binding.
    4. dna polymerase then binds to sites with primers (as thats wer the double strands are). dna polymerase builds the double strand by using the free NTPs and ddNTPs. (the ddNTPs lack a hydroxy group, thus if they bind to a chain, they stop that chain as the gydrocy group is required to make a bond with the next nucleoside).
    5. due to the ddNTP, different lengths of DNA fragments are produced in a mixture.
    This process (1 to 5) is genome sequencing, from step 5 we go onto electrophoresis.

    Where does BAC come into this? well the above genome sequencing is for small genomes only (100,000 bases). for the HUMAN GENOME (which has loads of bases) it undergoes another first step before the above. What happens is that the genome is treated with restriction enzymes, thus cutting down the genome into smaller fragments. the same restriction enzymes (used for each cut) are used on a 'Bacteria Artifical Chromosome' (aka, BAC) this is basically a man-made plasmid. The complementary sticky ends of the two (dna fragment and BAC) forms a recombinant DNA (rDNA). Now each rDNA contains a different part of the human genome. As you will notice we now have a smaller genome (around 100,000 bases) so we can carry out genome sequencing on each separately (so steps 1 to 5). After this is done, to recreate/recombine the human genome a very clever computer is used which does it.

    AND THAT IS IT! loool long i know, but ive summarised 3 processes. I would answer the exam questions with these personally as they cover what the book goes over and a bit more, thus covering all the marks for tht particular question.
    (btw i did this from memory without looking at books etc so if i have missed a step out let me knw!!)
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    How come everyone is getting different answers for sequencing of a genome? What's the answer?

    My teacher said we don't need to know about BAC's but everyones talking about them!
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    Anyone summarise Meiosis? Looking through past papers for topics applicable to F215...there could be an essay on Meiosis...
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    (Original post by Mobs25)
    Lol i know wot u mean every1 has somehting they hate and cant get in unit 5 (for me its some of the genetics)

    PCR is basically the copying the DNA sample. Ill beak it down into points:
    1. DNA molecule is mixed with DNA polymerase (Taq polymerase), primers and free dna nucleotides.
    2. the mixture is heated (to 95degrees), breaking the hydrogen bonds between the DNA molecule, thus we are left with two DNA single strands.
    3. the heat is bought down to 60 degrees, enables primers to now bind (anneal) to its complementary sequence on a specific part of the strands. this forms double strands on part of the dna single-strand.
    4. the heat is bought upto 75degrees, now the Taq polymerase (special as it is able to work in high temps) can now bind to double strands on the DNA strand and use free dna nucleotides to continue the double strand.
    5. thus we are left with two DNA double strands which are identical to the original DNA molecule we started with.
    6. This process can be repeated with these two new DNA molecules, thus we get 4 DNA molecules after the 2nd cycle, repeat PCR for these 4 we get 8 etc.

    Thats PCR, now Genome Sequencing is:
    1. sample of dna is denatured to reveal two DNA single strands.
    2. these are then mixed with DNA polymerase, free NTPs (nuleoside triphosphate), ddNTP (dedioxynucleoside triphostphate) and primers.
    3. primers anneal to the dna strands via specific complementary binding.
    4. dna polymerase then binds to sites with primers (as thats wer the double strands are). dna polymerase builds the double strand by using the free NTPs and ddNTPs. (the ddNTPs lack a hydroxy group, thus if they bind to a chain, they stop that chain as the gydrocy group is required to make a bond with the next nucleoside).
    5. due to the ddNTP, different lengths of DNA fragments are produced in a mixture.
    This process (1 to 5) is genome sequencing, from step 5 we go onto electrophoresis.

    Where does BAC come into this? well the above genome sequencing is for small genomes only (100,000 bases). for the HUMAN GENOME (which has loads of bases) it undergoes another first step before the above. What happens is that the genome is treated with restriction enzymes, thus cutting down the genome into smaller fragments. the same restriction enzymes (used for each cut) are used on a 'Bacteria Artifical Chromosome' (aka, BAC) this is basically a man-made plasmid. The complementary sticky ends of the two (dna fragment and BAC) forms a recombinant DNA (rDNA). Now each rDNA contains a different part of the human genome. As you will notice we now have a smaller genome (around 100,000 bases) so we can carry out genome sequencing on each separately (so steps 1 to 5). After this is done, to recreate/recombine the human genome a very clever computer is used which does it.

    AND THAT IS IT! loool long i know, but ive summarised 3 processes. I would answer the exam questions with these personally as they cover what the book goes over and a bit more, thus covering all the marks for tht particular question.
    (btw i did this from memory without looking at books etc so if i have missed a step out let me knw!!)
    so sequencing genome is same as sequencing and copying DNA.... coz i am a bit confused....:confused: bcoz when you talked about genome sequencing..you described DNA sequencing
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    (Original post by greenford)
    so sequencing genome is same as sequencing and copying DNA.... coz i am a bit confused....:confused: bcoz when you talked about genome sequencing..you described DNA sequencing
    (Original post by slacker07906)
    How come everyone is getting different answers for sequencing of a genome? What's the answer?

    My teacher said we don't need to know about BAC's but everyones talking about them!

    Genome is the sum of the genetic information in a organism, that genetic information is DNA. So yeh DNA sequencing is similar genome sequencing but at a smaller scale. It doesn't matter, we need to know the steps for it only.

    Quick DNA replication summary:
    1. DNA polymerase attaches onto DNA molecule
    2. DNA unwinds and unzips, breaking hydrogen bonds
    3. free dna nucleotides in the nucleus are joined together by complementary base paring
    4. the sugar-phosphate backbone joins with covalent bonds (phosodiester bonds)
    5. you are left with two new dna molecules identical to the original dna

    Difference is that in DNA replication we don't use NTPs, ddNTPs etc. We don't need to know about DNA replication for unit 5, we do need to know about protein synthesis. But, synoptic question on dna rep? maybe

    I hope that helps people who are confused with genome sequencing. From what i have seen my steps above and in my previous post are correct. Maybe the fact im using ddNTP and NTP is confusing, that part is basically the chain-terminator reaction. For ref, pages 166 to 167 (this talks about BAC). Pages 172 to 173 (genome sequencing).

    @slacker07906, i wouldn't imagine we need to know about BAC as that process is just telling us how the human genome project worked and how they did it all, its not on the spec to learn it. What is on the spec is the genome sequencing which is what ive summaried in my previous post.
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    (Original post by intellectual1)
    Anyone summarise Meiosis? Looking through past papers for topics applicable to F215...there could be an essay on Meiosis...
    There is a summary above from someone, and i agree i think meiosis is to be a big question as it is a big chunky part and is a nice tricky one as it includes crossing over and assortment of chromosomes and chromatides! (that reminds me need to go over that lol)
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    (Original post by merrmerr)
    34/40 is usually the mark for an A so 80% therefore 48/60 ums
    Hope i helped!

    (Original post by sportycricketer)
    yeah you're right
    Thank you
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    (Original post by heartskippedabeat)
    Thank you
    http://www.google.co.uk/url?sa=t&sou...A9Vy-w&cad=rja

    AS Bio ABCDE 34 31 28 25 22
    A2 Bio ABCDE 34 31 28 25 22

    The boundaries are higher than usual ie

    A 85%
    B 78%
    C 70%
    D 63%
    E 55%
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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
    Hey, thanks for the notes, they look really good. What grade did you get with them?
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    I was going through some past paper question and there couple of questions on Sterile Hybrid... just wondering do we need to know about that as the book does not talk about it anywhere
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    For those of you who are doing this exam, i suggest go and watch X-men the movie. Although not surprising, there was a lot of biology in the movie related to this unit. I went on saturday and it told a lot about mutations, apotosis and **** like that. I cant forget it now as it has re jogged my memory. If you do biology, you'll enjoy it
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    Hey guys!

    Need a little help with this please..

    Deleted


    Many thanks if you can help out! :rave:


    Just figured it out :facepalm: .. Thanks anyway
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    I was going through some past paper question and there couple of questions on Sterile Hybrid... just wondering do we need to know about that as the book does not talk about it anywhere
    Isn't that to do with the artificial selection to produce bread wheat?
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    (Original post by Mobs25)
    Lol i know wot u mean every1 has somehting they hate and cant get in unit 5 (for me its some of the genetics)

    PCR is basically the copying the DNA sample. Ill beak it down into points:
    1. DNA molecule is mixed with DNA polymerase (Taq polymerase), primers and free dna nucleotides.
    2. the mixture is heated (to 95degrees), breaking the hydrogen bonds between the DNA molecule, thus we are left with two DNA single strands.
    3. the heat is bought down to 60 degrees, enables primers to now bind (anneal) to its complementary sequence on a specific part of the strands. this forms double strands on part of the dna single-strand.
    4. the heat is bought upto 75degrees, now the Taq polymerase (special as it is able to work in high temps) can now bind to double strands on the DNA strand and use free dna nucleotides to continue the double strand.
    5. thus we are left with two DNA double strands which are identical to the original DNA molecule we started with.
    6. This process can be repeated with these two new DNA molecules, thus we get 4 DNA molecules after the 2nd cycle, repeat PCR for these 4 we get 8 etc.

    Thats PCR, now Genome Sequencing is:
    1. sample of dna is denatured to reveal two DNA single strands.
    2. these are then mixed with DNA polymerase, free NTPs (nuleoside triphosphate), ddNTP (dedioxynucleoside triphostphate) and primers.
    3. primers anneal to the dna strands via specific complementary binding.
    4. dna polymerase then binds to sites with primers (as thats wer the double strands are). dna polymerase builds the double strand by using the free NTPs and ddNTPs. (the ddNTPs lack a hydroxy group, thus if they bind to a chain, they stop that chain as the gydrocy group is required to make a bond with the next nucleoside).
    5. due to the ddNTP, different lengths of DNA fragments are produced in a mixture.
    This process (1 to 5) is genome sequencing, from step 5 we go onto electrophoresis.

    Where does BAC come into this? well the above genome sequencing is for small genomes only (100,000 bases). for the HUMAN GENOME (which has loads of bases) it undergoes another first step before the above. What happens is that the genome is treated with restriction enzymes, thus cutting down the genome into smaller fragments. the same restriction enzymes (used for each cut) are used on a 'Bacteria Artifical Chromosome' (aka, BAC) this is basically a man-made plasmid. The complementary sticky ends of the two (dna fragment and BAC) forms a recombinant DNA (rDNA). Now each rDNA contains a different part of the human genome. As you will notice we now have a smaller genome (around 100,000 bases) so we can carry out genome sequencing on each separately (so steps 1 to 5). After this is done, to recreate/recombine the human genome a very clever computer is used which does it.

    AND THAT IS IT! loool long i know, but ive summarised 3 processes. I would answer the exam questions with these personally as they cover what the book goes over and a bit more, thus covering all the marks for tht particular question.
    (btw i did this from memory without looking at books etc so if i have missed a step out let me knw!!)
    Thanks so much for that! I've been over it this morning and it's so much clearer in my head. Love it when something clicks I hope this comes up now!
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    (Original post by greenford)
    I was going through some past paper question and there couple of questions on Sterile Hybrid... just wondering do we need to know about that as the book does not talk about it anywhere
    It's on page 145. I think we do as on the spec. it says 'Describe how artificial selection has been used to produce bread wheat'.

    I don't really get it either though :/
 
 
 
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