The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in
A) a base-pair substitution.
B) a nucleotide mismatch.
C) a frameshift mutation.
D) a polypeptide missing an amino acid.
E) a nonsense mutation.

Question

Quizplus · Accepted Answer

The deletion of a single codon in the genetic code of people with cystic fibrosis results in the absence of a specific amino acid in the polypeptide chain, rather than a frameshift or a substitution. This is because a codon, which is a sequence of three nucleotides, codes for a single amino acid. Removing one codon thus removes one amino acid from the polypeptide, not altering the reading frame or substituting nucleotides.

The Most Commonly Occurring Mutation in People with Cystic Fibrosis