一道生物题 有关于遗传疾病的问题Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to reveal sickle-cell trait. Based on thi
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一道生物题 有关于遗传疾病的问题Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to reveal sickle-cell trait. Based on thi
一道生物题 有关于遗传疾病的问题
Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to reveal sickle-cell trait. Based on this incomplete information, calculate the probability that if this couple has a child, the child will have sickle-cell disease.
一道生物题 有关于遗传疾病的问题Karen and Steve each have a sibling with sickle-cell disease. Neither Karen nor Steve nor any of their parents have the disease, and none of them have been tested to reveal sickle-cell trait. Based on thi
Would you mind if I answer in English,'cause I haven't used Chinese for a while.Ok,let's start.
First,the answer is 1/16.
Let's use A&a respectively to stand for the dominant and recessive alleles of the sickle-cell disease.According to the problem discribed,we could easily deduce that the genotype of both Karen and Steve's parents are "Aa".That means that both Karen and Steve are 50% "a" allele carrier (since Karen and Steve must not be aa based on their phenotypes,so they are 25%AA,50%Aa).So they each have 25% to give "a" allele during mating (50% time 50%).So the final probability for them to have a sickle-cell-diseased child is 25% times 25% （or (1/4)*(1/4)）,equals to 1/16.
2/3*2/3*1/4=1/9