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    (Original post by pinksham)
    hii! could anyone explain epistasis 2 me pleease! i dont get it at all.. i understand that it when it masks 1 gene or works in a complemetary way with another gene. but i dont undersatnd the examples. thanks!!!
    I explained epistasis in some depth a couple of spreads back, so see if you can find the post.

    Epistasis is the interaction between different gene loci, where one locus masks or suppresses the expression of another gene locus. Epistasis will not result in the normal ratios that you would expect from dihybrid/monohybrid crosses i.e 9:3:3:1 and 3:1

    There are different ways that genes can interact. Firstly antagnositically to cause masking, or in a complementary way.

    When genes are acting antagonistically this can be due to either dominant epistasis or recessive epistasis. Dominant epistasis is where the presence of a dominant allele at the first locus prevents the expression of the allele at the second locus, the first locus is termed epistatic to the second, of which is called hypostatic.

    In recessive epistasis the prescence of a homozygous recessive allele prevents the epression of the genes at the second locus.

    When they are working in a complementary fashion, then the homozygous presence of a recessive allele will work to prevent the expression of the allele at either locus. So if aa, was expressed on the first, it prevents anything being expressed on the second, and if aa is present on the second, then it prevents anything from being expressed on the first.

    I used some examples in my other explanation.
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    finished the whole biology book yaaay :woo::eek3:
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    (Original post by blueberry123)
    finished the whole biology book yaaay :woo::eek3:
    :eek3: :eek3: :eek3:
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    Is nobody scared about how synoptic this paper is said to be? like 50% synoptic and they can ask you anything from the last 2 years! + the unit is so big, so i dont know what to do really!

    How is everyone else feeling or doing for this?
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    (Original post by redfanatic)
    Is nobody scared about how synoptic this paper is said to be? like 50% synoptic and they can ask you anything from the last 2 years! + the unit is so big, so i dont know what to do really!

    How is everyone else feeling or doing for this?
    Where did you hear that it is going to be 50% synoptic? :eek3: ... I hope not... pfff .. we surely deserve a decent paper after january's?
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    (Original post by win2kpro)
    Where did you hear that it is going to be 50% synoptic? :eek3: ... I hope not... pfff .. we surely deserve a decent paper after january's?
    My teacher. And that this is how it has always been, as it is the last paper we will do hence supposed to show all our knowledge. But i know what you mean. I was terrified to hear that.

    Also, can someone give me the links to all the revision packs and questions that have been uploaded, as theres 55 pages and i didnt want to really have to look through each page!

    thanks
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    (Original post by redfanatic)
    Is nobody scared about how synoptic this paper is said to be? like 50% synoptic and they can ask you anything from the last 2 years! + the unit is so big, so i dont know what to do really!

    How is everyone else feeling or doing for this?
    I am feeling good.Really forward to it.Bring it on OCR!
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    (Original post by win2kpro)
    Where did you hear that it is going to be 50% synoptic? :eek3: ... I hope not... pfff .. we surely deserve a decent paper after january's?
    we definately do, I hope they've sorted themselves out now because this is the last chance
    I didnt think that the Jan paper was all that synoptic even though people were banging on about revising all AS stuff. If it does I hope it just comes back
    not an excellent strategy

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    (Original post by clad in armour)
    we definitely do, I hope they've sorted themselves out now because this is the last chance
    I didnt think that the Jan paper was all that synoptic even though people were banging on about revising all AS stuff. If it does I hope it just comes back
    not an excellent strategy

    Although no one told me about it being synoptic but its def. gonna be one.... as lots of AS along with f214 mod. parallels with f215. Go for nervous system for instance or perhaps the conversion of ATP / *hint* gibberlins.
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    (Original post by ibysaiyan)
    Although no one told me about it being synoptic but its def. gonna be one.... as lots of AS along with f214 mod. parallels with f215. Go for nervous system for instance or perhaps the conversion of ATP / *hint* gibberlins.
    actually your right, theres the muscles stuff isnt there
    forgive my ignorance but what do plant hormones have to do with ATP?
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    Completed the f215 module today :shock:
    Anyhows the last chapter was quite dull *yawns* on memory,learning. If anyone has got any question on f215 stick it down =}
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    (Original post by ibysaiyan)
    Completed the f215 module today :shock:
    Anyhows the last chapter was quite dull *yawns* on memory,learning. If anyone has got any question on f215 stick it down =}
    Well done man :thumbsup: - Im nearly done too! Am on the sliding filament model atm, hopefuly done with f215 by midnight, or maybe 2moro if I am lazy :p:
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    (Original post by clad in armour)
    actually your right, theres the muscles stuff isnt there
    forgive my ignorance but what do plant hormones have to do with ATP?
    Yep. There was this past paper question on it. Basically GA is made in the embryo fo the seed. From there it diffuses outside to the aleurone layer (enzyme layer) where GA+enzymes +endosperm(food source) = Energy.
    How this is acheived is by the work of amylase on starch which breaks it into glucose and so forth.
    =}
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    (Original post by win2kpro)
    Well done man :thumbsup: - Im nearly done too! Am on the sliding filament model atm, hopefuly done with f215 by midnight, or maybe 2moro if I am lazy :p:
    cools muslce work heh? yep is fun x D myosin/actin/myso troponin/myosin/power stroke/the bands/Ca ions/along with sarcomere and sacroplasmic reticulum. Now whats the name of that filament which covers the pores where myosin head attach? :mad:
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    (Original post by ibysaiyan)
    cools muslce work heh? yep is fun x D myosin/actin/myso troponin/myosin/power stroke/the bands/Ca ions/along with sarcomere and sacroplasmic reticulum. Now whats the name of that filament which covers the pores where myosin head attach? :mad:
    tropomyosin subunits?
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    (Original post by win2kpro)
    tropomyosin subunits?
    err sure? xD ok then xD
    although i bet mary jones says anything but that let me look. :p:
    edit: yes xD
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    (Original post by ibysaiyan)
    Yep. There was this past paper question on it. Basically GA is made in the embryo fo the seed. From there it diffuses outside to the aleurone layer (enzyme layer) where GA+enzymes +endosperm(food source) = Energy.
    How this is acheived is by the work of amylase on starch which breaks it into glucose and so forth.
    =}

    excuse my slow brain but I'm still confused and you've lost me after the GA was made in the embryo :confused:
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    (Original post by blueberry123)
    excuse my slow brain but I'm still confused and you've lost me after the GA was made in the embryo :confused:
    GA aka gibberlins is diffused out from the embryo to the enzyme layer.There GA stimulates amylase enzyme which hydrolyzes starch into glucose.The starch (food source) is called endosperm.Glucose then is used in Aerobic respiration.
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    (Original post by ibysaiyan)
    GA aka gibberlins is diffused out from the embryo to the enzyme layer.There GA stimulates amylase enzyme which hydrolyzes starch into glucose.The starch (food source) is called endosperm.Glucose then is used in Aerobic respiration.


    much better ,thanks
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    (Original post by blueberry123)
    much better ,thanks
 
 
 
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