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    (Original post by hussaincute)
    lol should I call it a coincidence? :P okay u explain it to me?
    okay basically the HIV virus's GP120 binds onto the CD4 receptors on the membrane of the lymphocyte- T cell, and then enters the cell. Reverse transcriptase turns the RNA into DNA. The cell starts to make viral RNA with help of Intergraze. It will then make viral proteins. Thus new viruses. it will then kill the cell when it leaves the cell. The T killer cells are alerted and they will destroy the T helper cells that are infected. This will lower the overall imunity of the person as there is a reduction in T helper cells. This means that the person is now prone to opertunistic infection. this means they might die from a disease such as TB
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    (Original post by amber109)
    Brad0440 explained it really well:

    There are three stages that follow the initial infection:

    The acute phase:
    -HIV antibodies appear in the blood (after 3-12 weeks)
    -The virus enters and destroys T-helper cells to replicate, causing a net loss of T-helper cells and an increase in HIV
    -A few weeks after the initial infection, the T-killer cells recognise and destroy infected T-helper cells

    The chronic/latent phase:
    -The action of T-killer cells keeps in check the number of HIV in the body, but cannot completely eliminate them
    -During this phase, opportunistic diseases (like TB) can reactivate and other illnesses like colds can take longer to get over than normally, due to a decreased immune system

    The disease phase:
    Eventually, the number of HIV in the body overwhelms the immune system and causes the T-helper cell count to drop dramatically, severely damaging the immune system and indicating the onset of AIDS
    This is a good basic explanation but what i was looking forward was explaining in detail the whole mechanism including receptors and bacteria involved and how HIV invade the normal cell?
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    (Original post by confusedgirl22)
    what exam board are you doing?
    whatever you've mentioned has NOTHING to do with the edexcel syllabus
    I completely agree
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    (Original post by Sravya)
    I completely agree
    thank you! i got so worried and then realized i actually have nothing to worry about.
    i have NEVER seen that in the past papers or in any past syllabus!
    STOP SCARING ME RIGHT BEFORE MY EXAM
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    (Original post by confusedgirl22)
    thank you! i got so worried and then realized i actually have nothing to worry about.
    i have NEVER seen that in the past papers or in any past syllabus!
    STOP SCARING ME RIGHT BEFORE MY EXAM
    Do you know where i can find some past paper questions from old syllabuses? Ive done all the past papers twice
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    can someone please outline the specific immune response?
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    (Original post by hussaincute)
    This is a good basic explanation but what i was looking forward was explaining in detail the whole mechanism including receptors and bacteria involved and how HIV invade the normal cell?
    -The protein membrane of the HIV virus fuses with the cell membrane (lipid bilayer)
    -The reverse transcriptase changes DNA of the cell into viral RNA. It goes through transcription/translation
    -The virus's RNA is now incooperated with the normal genetic material and leaves the cell with the cell membrane around it - can't be detected
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    (Original post by Sravya)
    Do you know where i can find some past paper questions from old syllabuses? Ive done all the past papers twice
    tbh, i've only done new syllabus papers. i would advise you not to do past ones as they might be slightly different and you don't want to get confused end minute.
    and if you've gone through them twice, that's fine... don't stress last minute!
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    (Original post by confusedgirl22)
    tbh, i've only done new syllabus papers. i would advise you not to do past ones as they might be slightly different and you don't want to get confused end minute.
    and if you've gone through them twice, that's fine... don't stress last minute!
    I wish.. i feel soo realxed about it.. (ill eat my words late) but i felt this way in jan i felt as if i knew everything and ended up with a C that showed me..but i really dont know what more to do..all the past papers i have done i have got an A* via the UMS but thats probably cause ive done it twice
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    (Original post by Sravya)
    Do you know where i can find some past paper questions from old syllabuses? Ive done all the past papers twice
    Someone has already posted them on this thread..probably on the 3rd or 4th page but m not exactly sure..they are really good.

    Posted from TSR Mobile
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    Hey can someone explain the difference between a DNA probe and DNA primer?
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    (Original post by AT95)
    Someone has already posted them on this thread..probably on the 3rd or 4th page but m not exactly sure..they are really good.

    Posted from TSR Mobile
    Thanks
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    (Original post by Sravya)
    I wish.. i feel soo realxed about it.. (ill eat my words late) but i felt this way in jan i felt as if i knew everything and ended up with a C that showed me..but i really dont know what more to do..all the past papers i have done i have got an A* via the UMS but thats probably cause ive done it twice
    Lol same, I was more prepared in Jan then I am now. I really thought I got an A* in Jan, but I also got a C. I realized it was not the content, that prevented me getting the grade, but it was the exam technique.

    The examiners want perfect answers, they want us to be specific. I also noticed in mark schemes, they state the obvious, and that also gets you marks. There is not much we can do really.
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    (Original post by Sravya)
    What are your predictions?
    I made a list of all the possible topics and looked at the patterns...
    Here is my prediction
    -Structure of chloroplast
    - Light dependant stage of photosynthesis
    -how the products of photosynthesis are used
    NPP/GPP
    Carbon Cycle
    Ecology prac
    Niches/Succession
    Cause of global warming and the effect of global warming
    Evidence for global warming
    Nature of the genetic code
    Post transcriptional change
    DNA profiling
    Transcription
    Bacteria vs Virus
    Barriers to infection
    TB
    Specific immunity
    Antibiotics prac
    Hospital Acquired infections
    I do hope this comes up! i would love edexcel so much!!!
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    Whats the difference between cell mediated immunity and the humeral response?
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    Hey guys so what are the topics likely to come up tomorrow for edexcel unit 4 biology?
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    (Original post by Sravya)
    okay basically the HIV virus's GP120 binds onto the CD4 receptors on the membrane of the lymphocyte- T cell, and then enters the cell. Reverse transcriptase turns the RNA into DNA. The cell starts to make viral RNA with help of Intergraze. It will then make viral proteins. Thus new viruses. it will then kill the cell when it leaves the cell. The T killer cells are alerted and they will destroy the T helper cells that are infected. This will lower the overall imunity of the person as there is a reduction in T helper cells. This means that the person is now prone to opertunistic infection. this means they might die from a disease such as TB
    i think reverse transcriptase converts DNA into Viral RNA isn it?
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    (Original post by confusedgirl22)
    what exam board are you doing?
    whatever you've mentioned has NOTHING to do with the edexcel syllabus
    im doing edexcel, it comes up in my textbook 'Edexcel A2 Biology' but i havent seen it in the CGP which is why i dont use it by itself
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    (Original post by hussaincute)
    i think reverse transcriptase converts DNA into Viral RNA isn it?
    Nope because HIV is a hetrovirus which means it has RNA in it..plus the cell has to make into DNA so that protein synthesis can occour
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    (Original post by HQazi)
    Thanks
    Lytic pathaway is when it leads to cell lysis right? the death of T-helper cells?
    yes, the host cells burst = releasing the large number of new virus particles to invade other cells i dont think the lytic pathway has anything to do with t helper cells
 
 
 
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