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    (Original post by tsr1)
    that's unit 5 stuff.. but I have understood it now... thanks
    Apologies, I didn't know which one you were referring to. As long as you know it now!
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    (Original post by SKK94)
    Isn't this chemiosmosis during cellular respiration?
    I thought in photosynthesis, the H ions from reduced NADP are pumped out of the thylakoids into the stroma?
    Yep, you're correct! I made the mistake of referring to Chemiosmosis in Aerobic respiration.
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    What do you guys reckon is going to come up (I know it's impossible to predict). Been thinking of things that I haven't seen too extensively in the past:
    Detailed description of TB and how it can lay dormant
    Written description of difference between active and passive immunity
    Description of PCR
    Carbon recycling
    Role of interferons

    Anything else?
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    (Original post by Selym95)
    Apologies, I didn't know which one you were referring to. As long as you know it now!
    no worries... I get them confused myself too...
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    DNA and protein synthesis

    1. Explain the nature of the genetic code (triplet code, non-overlapping and degenerate).
    2. Explain the process of protein synthesis (transcription, translation messenger RNA, transfer RNA, ribosomes and the role of start and stop codons) and explain the roles of the template (antisense) DNA strand in transcription, codons on messenger RNA, anticodons on transfer RNA.
    3. Explain how one gene can give rise to more than one protein through post-transcriptional changes to messenger RNA.

    Could someone please briefly explain these spec points?
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    #lifesaver
    thank you!

    (Original post by SKK94)
    It is the gradual change in structure and species composition in a community.
    There are two types:
    - Primary
    - Secondary

    Primary succession:
    - starts with bare rock
    - pioneer species like lichen/moss appear
    - they grow, with time filling up small cracks/holes in the rock
    - the rocks start breaking down ( sometimes with the help of erosion as well) - organic matter starts to collect
    - eventually forming humus (organic matter that cannot be broken down further)
    - humus soon becomes soil
    - this allows for more species, like grass to grow and develop roots
    - as more water and nutrients collect in the soil, bigger plants can grow, like trees etc.
    - finally a climax community is formed.

    Features of a climax community:
    - made up of species of animals and plants
    - maximum biodiversity is reached
    - biodiversity remains constants until an interruption (e.g natural disaster, human activity)

    Secondary succession:
    - similar to primary succession
    - but starts off with soil, instead of rock
    - occurs after major damage to the habitat (fire, natural disaster etc)

    Note:
    *a climax community formed due human intervention is known as a plagioclimax
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    (Original post by nukethemaly)
    DNA and protein synthesis

    1. Explain the nature of the genetic code (triplet code, non-overlapping and degenerate).
    2. Explain the process of protein synthesis (transcription, translation messenger RNA, transfer RNA, ribosomes and the role of start and stop codons) and explain the roles of the template (antisense) DNA strand in transcription, codons on messenger RNA, anticodons on transfer RNA.
    3. Explain how one gene can give rise to more than one protein through post-transcriptional changes to messenger RNA.

    Could someone please briefly explain these spec points?
    1. Triplet- sequence of 3 bases on DNA that determines a single amino acid
    Overlapping - the triplets do not overlap which mean no base from one triplet is a part of another triplet avoiding confusion about which amino acid it is coded for
    degenerate- different codons code for one amino acid. mostly the first 2 nucleotides determine the amino acid so if a point mutation occurs on the 3rd base it will not affect the type of protein.


    3. post transcriptional changes lead to a greater variety in the phenotype than is coded for. Introns (non coding areas) are removed and exons (coding areas) are joined together to form a single long molecule. this is the process RNA splicing with the enzyme spliceosome). sometimes extrons are removed which leads to mRNA strands from the same DNA strand leading t slight different amino acids. So basically one gene can code for several different polypeptides due to this post transcriptional changes
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    hi ravz:eek::eek:
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    heyyy broooo! ready for bio???
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    (Original post by CONFUSED19)
    I cant access it.
    Do you think you could link it?

    Message me your e-mail address then I can send you the files.
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    (Original post by raves)
    heyyy broooo! ready for bio???
    Do you have any good bio unit 4 notes?? i cant seem to find any :/
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    (Original post by saladesilva.13)
    Do you have any good bio unit 4 notes?? i cant seem to find any :/

    no i couldnt find any :/ just use the revision guide and our notes. don't know if thats enough though :/
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    (Original post by raves)
    no i couldnt find any :/ just use the revision guide and our notes. don't know if thats enough though :/




    Can u please answer this ? whats the use of antisense strand in DNA? its in the specification
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    Can someone please tell me the difference between Reverse transcriptase, DNA and RNA polymerase????
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    (Original post by iwantopas19)
    Can u please answer this ? whats the use of antisense strand in DNA? its in the specification
    It's the strand that contains the bases for a specific polypeptide chain. It acts as a template for the formation of mRNA (transcription), so that this information can be carried out of the nucleus, to the ribosome for translation to occur.
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    (Original post by iwantopas19)
    Can someone please tell me the difference between Reverse transcriptase, DNA and RNA polymerase????
    The main difference is in their function:
    - DNA polymerase: assembles complementary DNA nucleotides along a single DNA strand, resulting in the formation of a double-stranded DNA molecule. This enzyme is involved in DNA replication.
    - RNA polymerase: assembles complementary RNA nucleotides along a single DNA strand, resulting in a molecule of mRNA. This enzyme is involved in transcription
    - Reverse transcriptase: as the name suggests, it does the opposite of transcription. It assembles complementary DNA nucleotides along a molecule of RNA (viral RNA) resulting in a single strand of complementary DNA (cDNA). This enzyme is involved in viral replication in host cells.
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    what your definition of gene flow would be? what context / example please?
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    okay I know this sounds so dumb, but seriously can someone please explain me what one earth HSW is? where can I find relavanet infos about HSW which is related to our specification? :dontknow:
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    (Original post by Trinitybabe)
    what your definition of gene flow would be? what context / example please?
    This might be helpful
    http://evolution.berkeley.edu/evosit...Geneflow.shtml
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    (Original post by Trinitybabe)
    what your definition of gene flow would be? what context / example please?


    ummm? can u be more specific ?

    gene : sequence of amino acids that codes for a particular protein or function.

    flow: u know the meaning

    basically it means the transfer of genes form one organisms to another through sexual reproduction.

    for example, if a geographical barrier arises between a population of a species, means they cannot interbreed therefor no gene flow between them.
 
 
 
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