Answer to Question #140565 in Zoology for chitra

Question

How sickle cell anemia and malaria are related to each other?

Answer 1

In the case of sickle cell anemia, two alleles may cause sickle cell anemia but carrying one allele is advantageous as it offers resistance against malaria. When heterozygous individuals contact malaria, their infected red blood cells assume the same sickle shape as those of homozygous individuals. The sickled cells lose potassium, killing the parasites, which limits their spread within the infected individual. Heterozygous individuals often survive malaria because the parasites do not multiply quickly inside them; their immune system can effectively fight the infection; and they retain a large population of uninfected red blood cells. Homozygous individuals are also subject to malarial infection, but because their infected cells do not sickle, the parasites multiply rapidly, causing a severe infection with a high mortality rate.

The heterozygotes carrying one recessive and one normal allele pass both the recessive (sickle-cell alleles) and normal allele to the offspring. So, both the alleles remain in the gene pool. If an individual inherits two recessive alleles, each from one parent, sickle cell anemia results.