Sickle cell anemia: a malformation of red blood cells that leads to anemia due to a mutation in the hemoglobin proteins carried by the blood cells. This mutation arises from a single substitution in the beta chains 6th position for valine, rather than glutamic acid. Substitution of a single amino acid causes improper folding of the protein and also reduces the net charge of the protein.
People that inherit the genes for both normal hemoglobin and sickle cell hemoglobin, termed heterozygous sickle trait for you genetics buffs, have a beneficial adaptation. The mutation is expressed codominantly, meaning both types of hemoglobin and red blood cells are present in their blood. From first assumption, you would think this would not be beneficial for the individual, but it turns out someone with sickle trait has a reduced risk for contracting malaria, one of the worlds biggest parasite killers (Plasmodium sp. to be exact ;)
Writing a lab paper about an experiment on hemoglobin, i started thinking about adaptations that we make in ourselves that if too expressed, are lethal, but in small doses can be beneficial for our survival in this dog eat dog world.
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