1. Use the letters A or a for the following question. If a condition is recessiv
ID: 99974 • Letter: 1
Question
1. Use the letters A or a for the following question. If a condition is recessive, can a parent who is homozygous dominant for a gene have a child with the recessive condition? Explain why or why not. Show your work with a Punnett square(s). (3 pt)
Explanation:
2. Use the letters A or a for the following question. Sickle cell anemia is a recessively inherited disorder. Individuals must have both recessive genes to have Sickle cell anemia. A male and female, both carriers for the Sickle cell gene, have decided to have a child. (3 pt)
A. What are the genotypes of the parents?
Mother’s genotype:
Father’s genotype:
B. What is the probability that the child will have Sickle cell anemia? Show your work with a Punnett square.
Probability for child with sickle cell anemia:
Explanation / Answer
If a condition is recessive, then both the parents should be carriers of the recessive allele. In this case since one parent is homozygous dominant (AA) then the other parent has to be a carrier (Aa) for the disease.
The parent who is homozygous dominant for a gene cannot have a child with recessive condition. The children can only be carriers of the disease.
2. For sickle cell anemia carriers, the Mother’s genotype: would be Aa and Father’s genotype: Aa
aa - 25% of the children would have the disease sickle cell anemia
Aa - 50% of the children would have sickle cell anemia trait
AA - 25% of the children would not have sickle cell anemia disease or trait
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