In the African tropics the maintenance of the sickle-cell allele in the human population can be attributed to?

Answer 1

Heterozygotes - those with sickle cell trait - show resistance to malaria. Therefore the survival rate of those with one sickle cell allele is higher than those with none - allowing for the trait to be passed on more frequently.

Answer 2

This recessive mutation is one amino acid difference in an allele of hemoglobin. The mutation causes the red blood cell to crenelate and is very debilitating and eventually fatal in homozygous recessive condition. The heterozygous condition confers some advantage in malaria country, especially to the young, by crenelating a good percentage of the red blood cells which make them almost impervious to the Plasmodium protist. Naturally, when homozygous recessive one can die from the sickle cell trait, when homozygous dominant one can die from malaria and when one is heterozygous for the trait the mutated allele produces enough crenelated RBC's to confer survival and reproductive advantage. Especially among the young in which malaria is very detrimental.

Answer 3

The extent to which it provides immunity to malaria.

Answer 4

Heredity is a factor in some diseases that affect specific populations ranging from hemoglobin disorders to Diabetes to Tay-Sachs.