The following is a summary of the possible sickle-cell genotypes and phenotypes: AA - completely normal AS - sickle-cell trait (this person has a combination of normal hemoglobin and the abnormal, sickled form of hemoglobin) SS - sickle-cell anemia (all abnormal hemoglobin) Make a punnett square for help answering the question: If both parents and heterozygous for sickle-cell disease, what are the possible genotypes and phenotypes for their children?
Added by Emily N.
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Punnett square: ``` A S A AA AS S AS SS ``` Show more…
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QUESTIONS MENDELIAN GENETICS AND PROBABILITY 1. If two people with sickle cell trait have children, what is the chance that a child will have normal RBCs in both high- and low-oxygen environments? What is the chance that a child will have sickle cell disease? Write the possible genotypes in the Punnett square. Normal RBCs in high- and low-oxygen environments ______ Sickle cell disease ______ a. What is the chance that a child will carry the HbS gene but not have sickle cell disease? ______ b. What are the chances that these parents will have three children who are homozygous for normal RBCs? (Show your work.) ______ c. What are the chances that these parents will have three children who have both normal and mutant hemoglobin beta chains? (Show your work.) ______ d. What are the chances that all three of their children will show the disease phenotype? (Show your work.) ______ e. What are the chances that these parents will have two children with sickle cell trait and one with sickle cell disease? (Show your work.) ______ f. In the cross above, if you know that the child does not have sickle cell disease, what is the chance that the child has sickle cell trait? ______
Adi S.
Sickle-cell disease is inherited as a recessive genetic disorder in humans; the normal hemoglobin allele $[H)$ is dominant to the sicklecell allele (h]. For two parents of genotype Hh (carriers), construct a Punnett square to show the possible genotypes of their children.
A gene is composed of two alleles. An allele can be either dominant or recessive. Suppose a husband and wife, who are both carriers of the sickle-cell anemia allele but do not have the disease, decide to have a child. Because both parents are carriers of the disease, each has one dominant normal-cell allele and one recessive sickle-cell allele. Therefore, the genotype of each parent is $S s .$ Each parent contributes one allele to his or her offspring, with each allele being equally likely. (a) List the possible genotypes of their offspring. (b) What is the probability that the offspring will have sickle-cell anemia? In other words, what is the probability the offspring will have genotype $s s ?$ Interpret this probability. (c) What is the probability that the offspring will not have sickle-cell anemia but will be a carrier? In other words, what is the probability that the offspring will have one dominant normal-cell allele and one recessive sickle-cell allele? Interpret this probability.
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