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    Good site to learn about mitosis, meiosis etc. : http://cyberbridge.mcb.harvard.edu/
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    (Original post by Remarqable M)
    gOOD
    Hey, just wondering when the Module 1 pack will be complete? x
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    How is revision coming along for everyone?
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    (Original post by ACDC)
    How is revision coming along for everyone?
    not bad:p: chicken genetic cross diagram is pissin me off:mad:
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    Module 1: Cellular Control


    "Genes Control the way in which cells function.
    Changes withing genes lead to variation and variation provides the raw material for evolution."






    I shall memorise this by heart
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    Explain the terms allele, locus, phenotype, genotype, dominant, co dominant and
    Recessive.
    someone?
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    Explain how meiosis and fertilisation can lead to variation through indepedent assortment of alleles. anyone?
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    I have a test on Module 1 tomorow- FAIL.
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    Genetic variation

    Meiosis

    - Crossing over between non-sister chromatids during Prophase I - forms a new combination of alleles.
    - Segregation of allelic pairs in Anaphase I - ensures that 1 member from each pair goes to each pole.
    - Independent assortment of maternal and paternal chromosomes during Metaphase I.
    - Independent assortment of sister chromatids during Metaphase II.

    Fertilisation

    - Genetic material from 2 unrelated individuals is combined to make a zygote.

    Mutations

    - Gene mutations in gamete forming (germ-line) cells.
    - Chromosome mutations - changes structure and number of chromosomes present.
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    (Original post by Remarqable M)
    Explain how meiosis and fertilisation can lead to variation through indepedent assortment of alleles. anyone?
    Check my latest post
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    (Original post by Remarqable M)
    Explain the terms allele, locus, phenotype, genotype, dominant, co dominant and
    Recessive.
    someone?
    awww man i got lot of catchup to do with BIO1!!! OH LORD 12 EXAMS ((
    grrrr
    anyhow i wish i ad enough energy to put down these definitions lately i have been active around "you know what stuff" .
    from what i can recall
    allele: you could say its different version of a gene or as said by my tutor it is a location of a gene (i know it more sounds like a locus which is a point).Dominant gene is one which is able to express its characteristic i.e phenotype.Co-dominance takes place when more than one alleles show their characteristic for example in blood groups.
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    Ok people i really need to undeerstand Meiosis -.- from what i vaguely remember is that it consists of 2 stages and in stage one during interpahse we have bi-variance (corssing over) of the er.... now what was it called.. grr chiasmata?:s
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    (Original post by ibysaiyan)
    Ok people i really need to undeerstand Meiosis -.- from what i vaguely remember is that it consists of 2 stages and in stage one during interpahse we have bi-variance (corssing over) of the er.... now what was it called.. grr chiasmata?:s
    check page 20 for my notes update on it, might help.
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    Wiki Support Team
    (Original post by ibysaiyan)
    awww man i got lot of catchup to do with BIO1!!! OH LORD 12 EXAMS ((
    grrrr
    anyhow i wish i ad enough energy to put down these definitions lately i have been active around "you know what stuff" .
    from what i can recall
    allele: you could say its different version of a gene or as said by my tutor it is a location of a gene (i know it more sounds like a locus which is a point).Dominant gene is one which is able to express its characteristic i.e phenotype.Co-dominance takes place when more than one alleles show their characteristic for example in blood groups.
    With co-dominance, I would really avoid talking about blood groups, since the co-dominance is only there when you have an A allele and a B allele together (in the case of my blood group ) If you have AO or BO it's not co-dominant. Examples I would use would be the roan coat colour in cattle (white and red allele together) or the tortoiseshell colour in cats (but then that is also sex linked)

    Allele - A alternative form of a gene.
    Dominant - An allele that is always expressed.
    Co-dominance - When two alleles for the same characteristic are expressed together.
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    Thanks everyone and thanks especially to xXxBaby-BooxXx
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    Could someone explain how you find out the genotypes for Mary, Astrid, Jack and Jane - page 125 in the Heinmann book?
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    And can anyone explain this diagram please ... totally don't get epistasis!

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    (Original post by xXxBaby-BooxXx)
    With co-dominance, I would really avoid talking about blood groups, since the co-dominance is only there when you have an A allele and a B allele together (in the case of my blood group ) If you have AO or BO it's not co-dominant. Examples I would use would be the roan coat colour in cattle (white and red allele together) or the tortoiseshell colour in cats (but then that is also sex linked)

    Allele - A alternative form of a gene.
    Dominant - An allele that is always expressed.
    Co-dominance - When two alleles for the same characteristic are expressed together.
    I dont get it whats wrong in representing them as co-dominance.The book by mary jones has them states as example too.In your post where you said AO OR BO thats simply the matter of no co-dominance since allele O is recessive.Its that simple
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    Key terms

    Allele - an alternative version of a gene.
    Loci - the position of a gene on its chromosome.
    Crossing over - where non-sister chromatids exchange alleles in Prophase I of Meiosis.


    Genotype - the alleles present in an individual or cell.
    Homozygous - 2 alleles that are identical e.g. AA
    Hetrozygous - 2 alleles that are different e.g. Aa

    Phenotype - observable characteristics of an organism.
    e.g. Hair colour


    Dominant - characteristic where the allele responsible is expressed in the phenotype. e.g. T for tall.

    Recessive - characteristic where the allele responsible is expressed in the phenotype when no dominant allele is present.
    - Only when homozygous.
    e.g. Cystic Fibrosis - homozygous recessive - cfcf.

    Codominance - characteristic where both alleles contribute to the phenotype.
    - Only when hetrozygous.
    e.g. Blood group A and B.


    Linkage - 2 or more genes at a location on the same chromosome.
    - At crossing over the chromatids on the alleles become linked together.
    - Reduces the number of phenotypes from the cross.

    Sex linkage - genes that have been inherited together on a sex chromosome (X/Y)
    - Y has less genes than X
    - Males are hemozygous - 1 allele is always present in the phenotype (XY)
    - Females are XX
    - X-linked diseases:
    - Haemophilia A - XH (normal) Xh (affected)
    - Duchenne Muscular Dystrophy (DMD) - XD (normal), Xd (affected)
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    Almost finished all notes on module 3 - its so far the easiest module. Really finding it hard to understand the genetic stuff from chapter 11 onwards. Will try to tackle that tomorrow. At school we haven't done module 2 so im going to have to teach myself that in the easter holidays =/. Cant wait to get biology out of the way tbh. The first unit was so much more interesting, this unit is bland and theres too much to cover
 
 
 
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