Question

. O . Using Pedigrees to hypothesize patterns of inheritance 5. For each of the pedigree charts on the following page, determine which pattern of inheritance most likely explains the observed pattern of traits in the family shown. Observe the general patterns in the pedigree charts on the following page o males vs females? parents with disease? Compare these patterns with the clues on the previous page to hypothesize a pattern of inheritance Based on this pattern of inheritance, use Table 2 to try and fill in genotypes for every individual. Remember that for some individuals, you may only be able to fill in one allele. Use a question mark for the second allele. (Some of the individuals are numbered and you will fill in their genotypes in Table 1 when you are sure about the pattern of inheritance) You can use some Punnett squares to verify that the genotypes of parents and offspring are possible. But remember, because human families are small in size, they will not exactly match the predicted ratios, so focus on whether or not the offspring are possible rather than the ratio. If not, then you may need to change your hypothesis to an alternative pattern of inheritance and repeat the process. Repeat for each pedigree. Then answer the following questions: . a. What is the most likely pattern of inheritance for Pedigree 1? Explain your answer b. What is the most likely pattern of inheritance for Pedigree 2? Explain your answer c. What is the most likely pattern of inheritance for Pedigree 3? Explain your answer. d. Based on these patterns of inheritance, what are the genotypes of the numbered individuals in the pedigrees? Table 1 Individual Genotype 2 3 4 5 6 7 8 9

Answer 1

(a) Pattern of inheritance for pedigree 1 is Autosomal recessive because it requires two copies of the recessive allele to express the disease.

(b) Pattern of inheritance for pedigree 2 is X-linked recessive because in X-linked recessive inheritance males are affected more commonly than females. Male has only one X chromosomes while females have two X chromosomes. Male express x linked recessive trait when they contain recessive allele. But female has to be contained both recessive alleles for being diseased.

(c).Pattern of inheritance for pedigree 3 is autosomal dominant because autosomal dominant trait will result in dominant phenotype when there is one or more copies of dominant alleles are present. It occuring frequency is equal both males and females.

(d).

Individual Genotype Aa Aa 2: 3 99 4 5 6 XY XX Xºy Aa 7, 8. Aa g. 99