Sickle-cell Anemia

The mutation that results in the sickle-cell disease phenotype is Non-conservative missense mutation. This mutation occurs in the hemoglobin beta gene (HBB) on chromosome 11, where a single nucleotide substitution (adenine to thymine) leads to the replacement of the amino acid glutamic acid with valine at the sixth position of the beta-globin chain. This non-conservative change alters the hemoglobin molecule’s properties, causing it to form abnormal structures under low-oxygen conditions, leading to the characteristic sickle shape of red blood cells associated with the disease. In the context of genetics, a conservative mutation refers to a type of missense mutation where one amino acid is replaced with another that is similar in its chemical properties, such as charge, size, and hydrophobicity. These similar properties mean that the function of the protein is more likely to be preserved, and the mutation may have a less drastic effect on the protein’s function compared to other types of mutations. On the other hand, a non-conservative missense mutation involves the replacement of an amino acid with another that has different chemical properties. This can significantly alter the protein’s structure and function because the new amino acid may interact differently with the rest of the protein or the protein’s environment. Such changes can have more profound effects on the protein’s activity, stability, or ability to interact with other molecules, often leading to detrimental effects on the organism. The key difference between conservative and non-conservative mutations lies in the similarity or difference in the chemical properties of the original and replacement amino acids. Conservative mutations substitute amino acids with similar properties, potentially maintaining the protein’s function, while non-conservative mutations replace amino acids with ones of different properties, which can significantly alter or disrupt the protein’s function. Problem: Which type of mutation results in the sickle-cell disease phenotype? A) Conservative mutation B) Frameshift mutation C) Non-conservative missense mutation D) Codon deletion