[Campbell Biology P.407] The text describes a mutation in the tyrosinase gene of the Asinara... | Practice Question

The text describes a mutation in the tyrosinase gene of the Asinara donkey where a C is changed to a G. This leads to an albino phenotype because a histidine is added instead of an aspartic acid, rendering the enzyme nonfunctional. Which type of small-scale mutation best describes this specific change?

  • A: Silent mutation.
  • B: Nonsense mutation.
  • C: Frameshift mutation.
  • D: Missense mutation.

Explanation

The text explicitly states that a C is changed to a G, which is a nucleotide-pair substitution. This substitution leads to a different amino acid histidine instead of aspartic acid being incorporated into the protein. This change of one amino acid to another due to a single nucleotide substitution is the definition of a missense mutation. The resulting loss of enzyme function and albino phenotype are consequences of this specific missense mutation.