Sickle cell anemia is caused by the sickle cell allele (HbS) of a gene that contributes to hemoglobin (Hb) production. The abnormal hemoglobin (hemoglobin-S) produced causes red blood cells to become deformed and block capillaries; tissue damage results. Affected individuals homozygous for the sickle cell gene rarely survive to reproductive age. Heterozygous individuals produce both normal hemoglobin and a small percentage of hemoglobin-S. These individuals are more resistant to malaria than are individuals who are homozygous for the allele for normal hemoglobin (HbA). Their red blood cells are prone to sickling when there is a deficiency of oxygen. Which of the following conclusions can be drawn from the information provided on sickle cell anemia? a. The sickle cell gene eventually will disappear because of its interaction with malaria. b. Malaria causes heterozygous individuals to be less fertile than homozygous individuals. c. In Africa, sickle cell anemia will disappear because it is lethal in the homozygous condition. d. In Africa, carriers for sickle cell anemia have an advantage over homozygous individuals
Sickle cell anemia is caused by the sickle cell allele (HbS) of a gene that contributes to
hemoglobin (Hb) production. The abnormal hemoglobin (hemoglobin-S) produced causes red
blood cells to become deformed and block capillaries; tissue damage results. Affected individuals
homozygous for the sickle cell gene rarely survive to reproductive age. Heterozygous individuals
produce both normal hemoglobin and a small percentage of hemoglobin-S. These individuals
are more resistant to malaria than are individuals who are homozygous for the allele for normal
hemoglobin (HbA). Their red blood cells are prone to sickling when there is a deficiency of oxygen.
Which of the following conclusions can be drawn from the information provided on
sickle cell anemia?
a. The sickle cell gene eventually will disappear because of its interaction with malaria.
b. Malaria causes heterozygous individuals to be less fertile than homozygous individuals.
c. In Africa, sickle cell anemia will disappear because it is lethal in the homozygous condition.
d. In Africa, carriers for sickle cell anemia have an advantage over homozygous individuals
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