Question

11. (8 m) Refer to the following pedigree, which traces the inheritance of a biochemical disorder. female not affected female affected 0 male not affected male affected a. (2 m) Does this disorder appear to be caused by an autosomal or sex-linked gene? Does this disorder appear to be caused by a dominant allele or by a recessive allele? Explain how you know this. b. (2 m) Fill in the genotypes of all affected individuals. Use A and a to label the alleles. Explain your reasoning C. (1 m) What is the possible genotype for George? Explain your reasoning. d. (1 m) What are the possible genotypes for Sam, Ann, Daniel, and Alan? Explain your reasoning

Answer 1

a.The disorder is caused by an autosomal gene. This is because the condition is appearing both in male and female equally. It is also not following criss-cross pattern of inheritance. The disorder is recessively inherited. This is because in the II generation, one parent is expressing the disorder. But the offspring is not expressing the disorder. Carl's parents are not expressing the disorder but Carla is expressing the disorder. Parents not having a trait and the offspring is expressing is one reason why it is considered a recessively inherited gene. So it is autosomal recessive disorder.

b.

George роолол I colo ro state I Daniel do mer te delen > T AU Daniele Ale I 742 .-:--> TV DIV cheiate her -- -- - -

b. All affected individuals are 'aa'. Because the inheritance is autosomal recessive. Tom, Wilma and their mother , Carla are all affected and 'aa'.

c. George is "Aa". This is because Tom and Wilma are affected individuals. In such a condition, both parents should pass on 'a' allele to the offspring. That is why George is Aa.

d.

Sam---Aa because one parent is 'aa' ( mother).

Ann----Aa because mother is 'aa'.

Daniel---also "Aa" because one parent is "aa"

Alan--- Also "Aa" because one parent is 'aa'

So all of them are heterozygous dominant.