question archive The pedigree above shows the inheritance of the dominant genetic disorder polydactyly
The pedigree above shows the inheritance of the dominant genetic disorder polydactyly
Subject:BiologyPrice: Bought3
The pedigree above shows the inheritance of the dominant genetic disorder polydactyly. People with this disorder have extra fingers and toes. An individual with an unaffected parent and a parent with polydactyly could either be heterozygous or homozygous recessive for the trait. Each unaffected person would be homozygous recessive for the trait. For example in the pedigree above individual II2 has polydactyly, indicated by the dark circle. It can be inferred that she has one dominant gene and one recessive gene because she is either heterozygous or homozygous dominant and I1 is homozygous recessive for the trait. Offspring, II3 and II4, do not have the disorder. Therefore, they are homozygous recessive for the trait. Notice also that II6 and II7, two unaffected parents, have unaffected offspring - III2. What can be inferred about II2, based upon the phenotype of III1?
Case Study:
"My name is Scott. My great grandfather Walter had hairy earlobes (HEs), but grandma Elsie did not. Walter and Elsie had three children: Lola, Leo, and Duane. Leo, the oldest, has HEs, as does the middle child Lola; but the youngest child, Duane does not. Duane never married and has no children. Leo married Bertie, and they have one daughter, Patty. In Leo's family, he is the only one with HEs. Lola married John, and they have two children: Carolina and Luetta. John does not have HEs, but both of his daughters do.""b
