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OCR Biology F212 Revision [3rd June 2013] (Now Closed) Watch

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    (Original post by Danny786)
    When proteins are heated to a high temperature their tertiary structure is disrupted.

    How does this happen?
    If I am correct, the mot obvious aspect to mention old be that a (very) high or higher temperatures, the hydrogen bonds will be the first to break.
    The same applies to the ionic bonding present also.
    The temperature effects the bonding of the polypeptides - normally the thing that makes up the earlier structures, such as Secondary - which would be hydrogen bonds - old be the topic of conversation.


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    Yes pretty much so - Molecules have more kinetic energy, so they vibrate more so the tertiary structure is disrupted causing it to become more fluid
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    Early bird gets the worm hey guys?
    good luck! xx
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    Could somebody just outline the pros and cons of in situ and ex situ for me please?


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    Ex-situ - advantages are people are made aware of conservation activities,a set policy can be framed by authorities,there is possibility of transferring a few individuals to same type of habitats miles away - so that there is a possibility of its sustenence in different lands.
    Disadvantages - great amount of monitoring has to be carried out to do away with poaching & killing them.In countries with very high density of population - conservation becomes too difficult a task.
    In case predators do not have enough prey,they do come near human habitations - endangering their lives & consuming domestic animals & especially human children
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    (Original post by scott18044)
    Yeah, I meant when I get out of there just before 11.
    I get'cha now Scott
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    Hey guys urm you know the female anopheles in each cycle of the plasmodium parasite it seems as though she has to bite the human twice?
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    (Original post by rival_)
    Hey guys urm you know the female anopheles in each cycle of the plasmodium parasite it seems as though she has to bite the human twice?
    No. The plasmodium will be transferred to the human if the anopheles is infected for log enough, as the plasmodium will be in the saliva of the mosquito, as it is used before withdrawal of any blood as an anti coagulant


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    (Original post by rival_)
    Hey guys urm you know the female anopheles in each cycle of the plasmodium parasite it seems as though she has to bite the human twice?
    To carry the disease she has to bite an infected person.
    To pass on the disease she has to bite an uninfected person.

    So it is a continuous cycle.

    Anyway, anybody know how DNA is replicated? It was a 6 mark question! :O
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    (Original post by PreppyNinja)
    To carry the disease she has to bite an infected person.
    To pass on the disease she has to bite an uninfected person.

    So it is a continuous cycle.

    Anyway, anybody know how DNA is replicated? It was a 6 mark question! :O
    Love this question! Double helix untwists. h2 bonds between bases break, dna unzips, leaving bases exposed. A free dna nucleotide comes along and binds to the exposed bases by h2 bonds and complimentary base pairing. Covalent bonds form between phosphate of one nucleotide and sugar of another to seal sugar-phosphate backbone.
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    Testing molecules:

    1. Protein: Buriet Test: NAOH, CUSO4 -> wait -> Purple -> Protein present.

    2. Starch: Idodine solution -> Turns black -> Starch present.

    3. Lipid: Ethanol -> Shake -> Water -> Wait -> Milky -> Lipid present.

    4. Sugars:
    Reducing: Benedict's Test: add Benedict's raegent in excess -> Heat to near boiling point -> Red -> Strong reducing sugar.
    Non-reducing: acid -> boil -> neutralise with NaHCO3 -> Benedict's Test -> So the reducing sugar test AGAIN.

    5. Colorimeter aka Concentration Test: different test tubes containing different concentrations (same volume) -> good old Benedict's Test (same volume) -> Leave for 24 hours / centrifuge to get rid of precipitate -> use colorimeter to measure light absorbance of solutions -> plot a calibration curve.


    Any mistakes?
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    Guys- any definitions you think may came up that haven't for a while? Really didn't learn them that well! Eek!
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    DNA replication:

    DNA Unzipped via DNA helicase enzymes
    Hydrogen bonds between complementary BP's broken
    Complementary bases exposed
    DNA polymerase comes along
    Attaches free, activated nucleotide via ATP to the exposed complementary BP's
    A-T, C-G
    Via semi-conservative replication
    2 molecules of double stranded DNA formed
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    I'll be so happy if the big 7/8 mark question is on something like conservation or a balanced diet.
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    (Original post by rival_)
    Hey guys urm you know the female anopheles in each cycle of the plasmodium parasite it seems as though she has to bite the human twice?
    Not quite, I don't think!
    The human old have to be infected...
    She'll have to extract blood from primarily for her initial meal, and the the transmission will take with the second helping in another host organism creating the damage to hepatocytes and erythrocytes.
    And so it goes on!
    :d


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    Similarities and differences between collagen and cellulose?


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    (Original post by Ché.)
    Not quite I don't think!
    She'll have to extract blood from primarily for her initial meal, and the the transmission will take with the second helping in another host organism creating the damage to hepatocytes and erythrocytes.
    And so it goes on!
    :d


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    (Original post by Ché.)
    Not quite, I don't think!
    She'll have to extract blood from primarily for her initial meal, and the the transmission will take with the second helping in another host organism creating the damage to hepatocytes and erythrocytes.
    And so it goes on!
    :d


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    (Original post by cab1094)
    Similarities and differences between collagen and cellulose?


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    They are both...fibrous?
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    (Original post by cab1094)
    Similarities and differences between collagen and cellulose?


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    Collagen:
    Polypeptide Chain
    35% (approx) Glycine
    Fibrous Protein
    3 strands linked together with Hydrogen bonds as cross-links
    Covalent bonds between separate collagen molecules
    As for function:
    Used in tendons/cartilage/bones are made initially from collagen I think/also used in beauty treatments lol

    Cellulose:
    B-Glucose Polymer
    1,4 glycosidic bonds #covalent
    Arranged into micro, then macrofibrils
    Function:
    Strengthen cell walls in plants
    Also indigestible by humans as we don't have the correct enzymes #activesite

    Sure there's more on cellulose but that's all I can remember at this moment!!
 
 
 
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