A portion of sequences for two types of hemoglobin are shown in the diagram.
The top sequence for wild-type hemoglobin is C-C-T, G-A-G, G-A-G. The bottom sequence for sickle-cell hemoglobin is C-C-T, G-T-G, G-A-G.
Sickle-cell anemia is caused by a mutation of one nucleotide in a gene. Using the diagram, which type of mutation is responsible for sickle-cell anemia?
A.
a frameshift mutation
B.
an insertion mutation
C.
an inversion mutation
D.
a substitution mutation
D. a substitution mutation
In sickle-cell hemoglobin, the nucleotide G in the second codon has been substituted with a T. This type of mutation is a substitution mutation, where one nucleotide is replaced with another.