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Biology 30 question. (Im stuck on it :( )

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    ********PLEASE NOTE THERE IS A PICTURE IN AN ATTATCHMENT. If anyone is able to help me with this question it would be awesome, I do not understand it and cant decide on an answer.

    Porphyrias are genetic disorders in which the hemoglobin component of red blood cells is abnormally assembled. Individuals with one type of porphyria called variegate porphyria are unable to synthesize an enzyme that is necessary for the production of the heme component of hemoglobin. Symptoms of variegate porphyria include sensitivity to light, abdominal pain, digestive disorders, and, in some cases, paralysis. This type of porphyria is inherited in an autosomal dominant mode.

    - adapted from Huskey, 2002
    Diagram by Robert J. Huskey, 1996. Variegate Porphyria Pedigree. Adapted and reprinted with permission.

    1. If individuals II-4 and II-5 have another child, the probability that this child will have variegate porphyria is
    A. 0.00 C. 0.50
    B. 0.25 D. 0.75
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    I think it's C - 0.5

    because one parent has the condition and as it's dominant, the child only needs one copy of the faulty allele to get the condition. The parent with the condition has one faulty allele and one 'normal' allele (you can tell that from their parents) so there is a 50:50 chance that the faulty allele will be inherited from this parent.

    Sorry I'm not very good at explaining, ask me any questions you need to make it clearer
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    Thank you !! I understand your explaination !! Again, thank you soo much !


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