Pergunta

Which of the following best describes sickle-cell anemia? (4 points) Caused by environmental factors that an individual was exposed to during pregnancy. A hereditary genetic mutation that causes a resistance to malaria. An inherited disorder that increases the risk of contracting malaria from mosquitos. A genetic mutation that is inherited from a dominant allele of one parent.
Solução

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RobertaMestre · Tutor por 5 anos
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B. A hereditary genetic mutation that causes a resistance to malaria.
Explicação
Sickle-cell anemia is a hereditary genetic disorder that affects the shape and function of red blood cells. It is caused by a mutation in the gene that codes for the beta-globin subunit of hemoglobin, the protein in red blood cells that carries oxygen. This mutation leads to the production of abnormal hemoglobin, known as hemoglobin S or sickle hemoglobin. The presence of sickle hemoglobin causes red blood cells to become rigid and take on a sickle shape, which can lead to various complications, including pain crises, anemia, and increased risk of infection. The condition is inherited in an autosomal recessive pattern, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disease. It is not caused by environmental factors during pregnancy, nor does it increase the risk of contracting malaria from mosquitoes. However, individuals with sickle-cell anemia do have some resistance to malaria, which is why the disease is more common in regions where malaria is endemic. This resistance is due to the fact that the sickle-shaped cells are less hospitable to the malaria parasite. The statement that sickle-cell anemia is caused by a dominant allele is incorrect; it is caused by a recessive allele.
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