For example, in the case of sickle beta thalassemia, the individual has inherited a gene for hemoglobin S. from one parent and a gene for beta-thalassemia from the other. Or, in the instance of SC disease, the individual has inherited a gene for hemoglobin S. from one parent and a gene for hemoglobin C. from the other.
The sickle cell trait in heterozygous carriers confers the resistance to malaria phenotype characterized by a dominant gene (Sickle cell anemia, Wikipedia). Because people with sickle trait were more likely to survive malaria outbreaks in Africa than those with normal hemoglobin, it is believed that sickle hemoglobin evolved as a protection against malaria.
Haplotypes of sickle cell disease are polymorphic restriction endonuclease sites in and around the mutant beta-globin gene Acording to Fields (2000), the existence of haplotypes specific to certain regions of the world suggests that the mutant beta globin gene arose separately in these locations. Because all of the areas in question are now or have been endemic locations of malarial infestation, the high incidence of sickle mutation is most often attributed to natural selection. Selection that actively maintains two or more alleles at a locus is called balancing selection (Malaria, sickle cell anemia, and balancing selection). Balancing selection can arise by the heterozygotes having a selective advantage, as in the case of sickle cell anemia. It can also arise in cases where rare alleles have a selective advantage. In extreme cases, balancing selection can maintain alleles in populations long enough for speciation to occur.
The mutation that produces sickle hemoglobin occurs spontaneously at a low rate (Fields, 2000). People with one sickle hemoglobin gene and one normal hemoglobin gene are somewhat more resistant to malaria than people with two normal hemoglobin genes. Therefore, people with sickle cell trait would have a better chance of surviving an outbreak of malaria.
Conclusion/Implications phenotype is equivalent to a genotype plus its development in a given environment. In only a narrow genetic sense does the genotype define the phenotype (Phenotype and genotype). Selection acts on...
These crises are a direct result of way in which the deformed red blood cells adhere to both each other and the insides of the blood vessel walls, blocking tissues from receiving oxygen. The disease is prevalent across some parts of Africa, the Middle East and India, which is due to the way in which the heterozygous form of the condition offers carriers a degree of protection against malaria,
Sickle Cell Anemia There are both advantages and disadvantages of having sickle cell anemia. How much benefit a person gets from sickle cell anemia's advantages, however, largely depends on where that person is located and what his or her environment is. The same concept applies to the disadvantages of this condition, although to a lesser extent. The root of the advantages and disadvantages of this disease pertain to its specific form
Sickle Cell (Rough Draft) Sickle cell anemia is a blood disease that causes badly formed red blood cells. The disease is genetec. Mostly people from Africa or other coutries around the Mediterraean Sea get it. In the United States, African-Americans are most likely to have it (Howard, 1995). Red blood cells are the blood cells that carry oxygen throughout the body. When a person has sickle-cell anemia the hemoglobon in the cell
Sickle cell anemia according to the U.S. National Library of Medicine/National Institutes of Health - NLM/NIH (2013), "is a disease in which your body produces abnormally shaped red blood cells." As the NLM/NIH further point out, the cells produced in this case ordinarily have a crescent-like shape. The red blood cells of an individual usually have a disk-like shape. It is this disk like shape that enhances and eases their
Sickle Cell Anemia As an inherited condition, it is presence of hemoglobin which tends to be abnormal that brings about sickle cell anemia. In basic terms, hemoglobin is a red blood cell protein whose main function is carrying oxygen. It is this hemoglobin abnormality that informs 'sickled' or distorted red blood cells whose survival is compromised as a result of the distortion and fragility. Though the prevalence of the condition largely
Another symptom that is often found is a yellowing of skin and eyes; this is a sign of jaundice due to the breakdown of red blood cells. Another sign is that children may show delayed growth and development. (Genetic Disease Profile: Sickle Cell Anemia) One of the aspects that problematizes this disease are the complications that can arise as a result of the lowering of body defenses and the increased
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