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    (Original post by Rosi M)
    Haha mental breakdown silently.. is that possible?
    trust me, it is
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    (Original post by CullenLoverX)
    trust me, it is
    Haha my mental breakdowns are quite ermm loud! Your quite talented
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    good luck everyone!
    Personaly, I'm going to revise till 10:30 (that is if i get off tsr!)
    wake up early in the morning and refresh everything in my head.
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    does anyone think anything on glycoproteins and glycolipids will come up? seeing as it came up in Jan 2010

    i still keep messing up that same question
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    (Original post by xMaGic)
    Describe the functions of glycoproteins in cell surface membrane? Anyone? - also dont understand cell signalling
    Can you tell me the exam paper this was from? I was just about to look for it.
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    what topics do you guys think will most probably come up??
    i know mitosis will defo come up
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    (Original post by Wilko94)
    Can you tell me the exam paper this was from? I was just about to look for it.
    It was in the January 2010 paper. I remember it being 4 marks + a QWC mark. You just had to give 3-4 explained functions of a glycoprotein and I think that there are a few functions in the book.
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    I think mitosis has a high chance of coming up and there probably a question on the heart, hopefully
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    Right.

    Can someone lay out for me the differences between a prokaryoric and a eukaryotic cell?
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    can we go through things to do with mitosis? here are some things i know

    Importance of mitosis.
    Asexual reproduction
    Growth of tissue
    Repair of tissues

    Interphase:
    DNA replication takes place by copying the genetic information and doubling the number of chromosomes.
    (when do we say chromatids and chromosomes? this confuses me esp in mark schemes)


    What are the G stages?
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    Honestly...i dunnaw what to revise, been cheking thruu older posts on the papers before, n goin thru the syllabus aint gnna help much as they always twist things abit...
    They should put summa in about genes n thaa saccaride stuff
    Anythin mainly i should be focusing on??
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    - Prokaryotic cells don't have membrane bound organelles such as mitochondria and chloroplasts- unlike eurkaryotic cells

    - The cell wall of prokaryotic cells is made of Murein not Cellulose

    - In prokaryotic cells respiration takes place in in specialised area of the membrane called mesosomes, whereas in eurkaryotic respiration takes place in mitochondria

    - In prokaryotic cells DNA is found in the cytoplasm in a single loop called bacterial chromosome and there may be small loops of DNA called plasmids. In prokaryotic cells DNA is not surrounded by a nuclear envelope- instead the general area in which the DNA lies is called the nuceloid.
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    (Original post by pastpaper-guy)
    can we go through things to do with mitosis? here are some things i know

    Importance of mitosis.
    Asexual reproduction
    Growth of tissue
    Repair of tissues

    Interphase:
    DNA replication takes place by copying the genetic information and doubling the number of chromosomes.
    (when do we say chromatids and chromosomes? this confuses me esp in mark schemes)


    What are the G stages?
    Gi is when the cell grows, and carries its normal functions

    Gii is when it readies itself for mitosis, it replicates all dna/organalles...
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    (Original post by Wilko94)
    Right.

    Can someone lay out for me the differences between a prokaryoric and a eukaryotic cell?
    prokaryotic cell-
    no nucleus
    contains no membrane bound organelles
    have smaller ribosomes compared to eukaryotic cells
    because they have no mitochontria ATP production takes place in mesosomes
    single strand of DNA found in cytoplasm
    sometiomes consists of flagella
    cell walls made up of meurin


    eukaryotic cells-
    contains membrane bound organnelles
    larger ribosomes
    has a nucleus
    ATP production takes place in mitochondria
    DNA found in nucleus
    cell walls made up us cellulose
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    From what i understand G stages is just where interphase has been broken down into different stages. So in G stages DNA is replicated, processes such as protein synthesis and respiration are being carried out and replicated DNA is being checked by proof-reading enzymes to make sure copying has been done properly.

    Does that answer the question?
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    They will always, 100% test you on plant cells. Theyve already done Xylem, so Im guessing now would be a great time to test us on the phloem cells, and translocation. As a means of revision for the replier (reply-ee?), tell me EVERYTHING, absolutely EVERYTHING, you know about phloem cells please?
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    (Original post by Wilko94)
    Right.

    Can someone lay out for me the differences between a prokaryoric and a eukaryotic cell?
    Prokaryotic (bacteria etc)
    • smaller, about 2-5um
    • ribosomes 18nm diameter
    • have naked dna
    • cell wall present
    • flagellum sometimes present


    Eukaryotic (animal and plant cell)
    • about 5-20um
    • have organelles (mitocondria etc)
    • you just need to know about eukaryotic really then you can compare all sorts from a normall cell
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    We say chromatid after the replicated chromosomes have shortened and thickened, so anything before then is chromosomes.
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    This is how the phloem is loaded with sucrose:

    - ATP is used by companion cells to actively load hydrogen ions out of their cytoplasm and into surrounding tissue.

    - This sets up a diffusion gradient and hydrogen ions diffuse back into the companions cells. Diffusion occurs across transporter proteins, enabling hydrogen ions to bring sucrose molecules back with it.

    - As the sucrose molecule concentration rises, sucrose molecules move from the companion cells through the plasmodesmata and into the sieve tube element.
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    Evidence for the use of the phloem

    - If a plant is supplied with radioactively labelled carbon dioxide, the carbon soon appears in the phloem

    - ringing a tree to remove the phloem causes sugars to collect above the ring

    _ An aphid feeding on the plant stem leaves mouthparts showing it is taking food from the phloem.
 
 
 
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