Sickle Cell Anemia is caused by what type of mutation?

Sickle Cell Anemia is caused by a point mutation, specifically a single nucleotide substitution in the gene coding for hemoglobin. In this case, the adenine (A) is replaced by thymine (T) at the sixth codon of the gene for the beta globin chain of hemoglobin. This alteration leads to the substitution of the amino acid valine for glutamic acid in the hemoglobin protein. This change in the protein's structure causes hemoglobin to polymerize under low oxygen conditions, resulting in the characteristic sickling of red blood cells.

Point mutations are precise alterations of a single nucleotide, which can significantly impact protein function and phenotype, as seen in Sickle Cell Anemia. In contrast, chromosomal mutations involve larger segments of DNA and can include deletions, duplications, or reorganizations of chromosome structure, which are not the case for Sickle Cell Anemia. Insertion and deletion mutations would involve the addition or loss of nucleotide sequences, respectively, which are not the mechanisms behind this specific disorder.