Under what circumstances is the mutation for hemoglobin S (sickle cell allele) beneficial? & when is it not?

Answer 1

Sickle cell is an anti-malarial mutation. It allows the cell to morph (into the sickle shape) in order to pass agglomerations of pathogens in the blood stream. Here is where it gets interesting. Did you know that the first discovery of a recessive condition expressing itself was found in the NFL. Black foot ball players were seen to be hitting the oxygen bottle very heavily in Denver (elevation one mile). Researchers look into the phenomenon. They found that many of the black athletes were carriers (recessive) for sickle cell. Under stress (thin atmosphere) they determined that the cells were sickling. So there is your negative. When a cell sickles it can not hold onto the heme molecule very well and anoxia ensues. Hope that helps

Answer 2

The hemoglobin S allele is a genetic mutation the has proved to be of benefit in areas where malaria is endemic, just as the various thalessemia alleles have done. The sickling occurs because the hemoglobin semi-crystallizes in the presence of low oxygen levels, cold temperatures, and in the presences of low pH's and certain chemicals such as 2,3 DPG. Its benefit only is seen in heterozygotes. As a cell sickles, the crystals of hemoglobin actually puncture and kill the malarial parasite (falciparium sp.). This allows the remaining hemoglobin A to continue to carry oxygen, and imparts a survival advantage to that human and therefore to its offspring

Answer 3

Heres what I do know...

Sickle cell anemia is prevailant in western africa ( in comparison to other parts of the continents) Because West Africa has the most maleria cases and people with sickle cell anemia CANNOT get maleria (the parasite cannot get in their blood cell due to the unique shape)
Therefore people with the hemoglobin S have thrived and survied more than people without the hemoglobin.

PS: the cells does not "morph!" ( as Peter O implies) that is rediculous! and this cell was first discover by an American scientist who owned a sickly slave.... its a long story but people have known of the existance of the hemoglobin S way before the NFL.