Phenylketonuria (PKU) is an inherited disease caused by a recessive allele. If a
ID: 178813 • Letter: P
Question
Phenylketonuria (PKU) is an inherited disease caused by a recessive allele. If a woman and her husband, who are both car riers, have three children, what is the probability of each of the following? All three children are of normal phenotype. One or more of the three children have the disease. All three children have the disease. At least one child is phenotypically normal. The genotype of F_1 individuals in a tetrahybrid cross is AaBbCcDd. Assuming independent assortment of these four genes, what are the probabilities that F_2 offspring will have the following genotypes? aabbccdd AaBBccDd AaBbCcDd AaBBCCdd AA BBCCDDExplanation / Answer
Answer:
7). AaBbCcDd x AaBbCcDd---Parents
Aa x Aa= AA (1/4), Aa (1/2), aa(1/4)
Bb x Bb= BB(1/4). Bb (1/2), bb(1/4)
Cc x Cc= CC (1/4), Cc(1/2), cc(1/4)
Dd x Dd= DD(1/4), Dd (1/2), dd(1/4)
a). aabbccdd = ¼ * ¼ * ¼ * ¼ = 1/256
b). AaBbCcDd = ½ * ½ * ½ * ½ = 1/16
c). AABBCCDD= ¼ * ¼ * ¼ * ¼ = 1/256
d). AaBBccDd= ½ * ¼ * ¼ * ½ = 1/64
e). AaBBCCdd = ½ * ¼ * ¼ * ¼ =1/128
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