Join TSR now and get all your revision questions answeredSign up now
    • Thread Starter
    Offline

    3
    ReputationRep:
    Hi guys,

    I know its the day before the exam, but, wanting to just fine tune my knowledge base.

    I am a little shaky on genetic disorders and inheritance.

    I chose D; 25%.

    I thought, the father was H h and the mother h h.

    But if she is h h; and the disorder is dominant, then wouldnt that mean there would need to be HH together? Using the genotype of father as H h and mother as h h, I get Hh Hh, hh, hh. Is that why the answer is 50%?
    Attached Images
     
    Offline

    0
    ReputationRep:
    The father is Hh and the mother is hh
    This means it is 50%
    H x h = Hh
    H x h = Hh
    h x h = hh
    h x h = hh


    Posted from TSR Mobile
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by SaffSmith)
    The father is Hh and the mother is hh
    This means it is 50%
    H x h = Hh
    H x h = Hh
    h x h = hh
    h x h = hh


    Posted from TSR Mobile
    I thought this was a dominant disorder, so the two dominant alleles would have to be present together; as in HH.

    You got the same results as me it seems, but Im a little confused as to how to properly interpet them. I am leaning towards that it is the Hh Hh; given that is dominant and the hh is the genotype of a non-sufferer of the condition. Is my thinking correct?
    Offline

    2
    ReputationRep:
    (Original post by apronedsamurai)
    I thought this was a dominant disorder, so the two dominant alleles would have to be present together; as in HH.

    You got the same results as me it seems, but Im a little confused as to how to properly interpet them. I am leaning towards that it is the Hh Hh; given that is dominant and the hh is the genotype of a non-sufferer of the condition. Is my thinking correct?
    If it's dominant only one H needs to be present.

    So: Hh hH all result in huntingtons for that question

    So Yh 50%
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by Nucleotide)
    If it's dominant only one H needs to be present.

    So: Hh hH all result in huntingtons for that question

    So Yh 50%
    Ok, stuck with this question,

    Sex linked condititon, carrier female; (must be heterozygous) so H h

    Male is un affected (must be homozygous dominant) HH

    HxH=HH
    H x H=HH
    Hxh =Hh
    Hxh=Hh

    So, the answer is 50%?
    Attached Images
     
    Offline

    0
    ReputationRep:
    (Original post by apronedsamurai)
    I thought this was a dominant disorder, so the two dominant alleles would have to be present together; as in HH.

    You got the same results as me it seems, but Im a little confused as to how to properly interpet them. I am leaning towards that it is the Hh Hh; given that is dominant and the hh is the genotype of a non-sufferer of the condition. Is my thinking correct?

    It is a dominant condition so is cause by a dominant allele which is the D.
    A dominant allele makes the phenotype whenever it is present i.e it doesn't not have to be DD, whenever a D is present in the phenotype that will control the phenotype.

    I hope this is a bit clearer xx
 
 
 
Poll
How are you feeling about your A-level results?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.