3. Sickle-cell anemia is an interesting genetic disease. Normal homozygous individuals (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. If 9% of an African population is born with a severe form of sickle-cell anemia (ss), what percentage of the population will be more resistant to malaria because they are heterozygous (Ss) for the sickle-cell gene?
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We know that 9% of the population is homozygous for the sickle-cell trait (ss), so the frequency of the "ss" genotype is 0.09. We can use the Hardy-Weinberg equilibrium equation to find the frequency of the "s" allele: p^2 + 2pq + q^2 = 1 where p is the Show more…
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In sickle-cell anemia normal homozygous individuals (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. If 9% of an African population is born with a severe form of sickle-cell anemia (ss) and the frequency of the recessive allele is 0.53, what percentage of the population will be more resistant to malaria because they are heterozygous (Ss) for the sickle-cell gene?
Adi S.
Sickle-Cell Anemia is an inherited red blood cell (RBC) disorder in which there aren't enough healthy blood cells to carry oxygen throughout your body. The disease causes aggregation of hemoglobin (Hb), the protein responsible for oxygen transport in RBCs. When Hb aggregates, it causes the formation of long, rigid polymer-esque rods of protein in RBCs. These rods cause the shape of normally round, flexible RBCs to instead sickle, preventing them from moving easily through blood vessels. Nucleotides 1-18 of the WT Hb gene are seen below. Sickle-cell anemia is caused by an A -> T mutation at position 14. 5' - GTCCACACTCCTGAGGAG - 3'. What is the resulting amino acid sequence of the WT Hb protein? What is the resulting amino acid sequence of the mutated Hb protein?
Shaiju T.
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