Answer
b.
Work Step by Step
Cystic fibrosis is a disease caused by the deletion of three bases from a protein called CTFR, which allows the passage of chloride ions into and out of a cell. The deletion of these three bases deletes a single amino acid, phenylalanine, from the protein. The loss of a single amino acid causes the entire protein to fold incorrectly. The body does not recognize this protein as functional, so it destroys the protein.
