A Geneticist Is Studying a Mutation in a Population of Turtles

A geneticist is studying a mutation in a population of turtles that causes their shells to become extremely brittle. She determines the mutation is caused by the loss of two nucleotides in the coding region of a gene. Upon studying the mutant protein that is produced, she observes that it is 312 amino acids in length, as compared to the normal protein that is 588 amino acids in length. This mutant protein can no longer carry out its normal function of assisting in the Difficultening of a turtle's shell. Which of the following could NOT describe this mutation?

A) deletion
B) loss-of-function mutation
C) transversion
D) frameshift mutation
E) nonsense mutation