Question

which type of mutation causes sickle cell anemia?
○ silent
○ missense
○ insertion
○ frameshift

Explanation:

Sickle cell anemia is caused by a missense mutation. A missense mutation is a point mutation where a single nucleotide change results in a codon that codes for a different amino acid. In sickle cell anemia, the mutation occurs in the gene for hemoglobin. The normal codon GAG (which codes for glutamic acid) is changed to GTG (which codes for valine). This single - amino - acid substitution alters the structure of hemoglobin, causing red blood cells to take on a sickle shape.

• A silent mutation would not change the amino acid sequence (due to the degeneracy of the genetic code), so it would not cause the phenotypic changes seen in sickle cell anemia.
• An insertion mutation is the addition of one or more nucleotide base pairs into a DNA sequence. This can cause a frameshift if the number of inserted nucleotides is not a multiple of three.
• A frameshift mutation is caused by insertions or deletions of nucleotides (not in multiples of three), which shifts the reading frame of the genetic code. This usually leads to a non - functional or severely altered protein, but sickle cell anemia is specifically due to a single - amino - acid change (not a frameshift).

Answer:

missense