Search results
Results from the WOW.Com Content Network
Sickle-cell anemia (SCA) is a genetic disorder caused by the presence of two incompletely recessive alleles. When a sufferer's red blood cells are exposed to low-oxygen conditions, the cells lose their healthy round shape and become sickle-shaped. This deformation of the cells can cause them to become lodged in capillaries, depriving other ...
A well-studied case is that of sickle cell anemia in humans, a hereditary disease that damages red blood cells. Sickle cell anemia is caused by the inheritance of an allele (HgbS) of the hemoglobin gene from both parents. In such individuals, the hemoglobin in red blood cells is extremely sensitive to oxygen deprivation, which results in ...
Sickle-cell disease and the associated trait are most prevalent in Africa and Central America, which is attributed to natural selection: the sickle-cell trait confers a survival advantage in areas with a high occurrence of malaria, which has a high death rate among individuals without the trait. [citation needed]
Sickle cell disease (SCD), also simply called sickle cell, is a group of hemoglobin-related blood disorders that are typically inherited. [2] The most common type is known as sickle cell anemia. [2] Sickle cell anemia results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. [2]
Natural selection is the differential survival and ... Natural selection is a cornerstone of modern biology. ... malaria in humans heterozygous for sickle-cell ...
Overdominance is a phenomenon in genetics where the phenotype of the heterozygote lies outside the phenotypical range of both homozygous parents. Overdominance can also be described as heterozygote advantage regulated by a single genomic locus, wherein heterozygous individuals have a higher fitness than homozygous individuals.
Sickle cell anemia is a classic example of the mixed benefit given by the staying power of pleiotropic genes, as the mutation to Hb-S provides the fitness benefit of malaria resistance to heterozygotes as sickle cell trait, while homozygotes have significantly lowered life expectancy—what is known as "heterozygote advantage". Since both of ...
The Price equation can describe any system that changes over time, but is most often applied in evolutionary biology. The evolution of sight provides an example of simple directional selection. The evolution of sickle cell anemia shows how a heterozygote advantage can affect trait evolution. The Price equation can also be applied to population ...