[Campbell Biology P.387] The experiment by Srb and Horowitz tested and supported the "one ge... | Practice Question

The experiment by Srb and Horowitz tested and supported the "one gene-one enzyme" hypothesis. Which of the following statements best describes how their results contribute to this hypothesis?

  • A: Each class of mutant was unable to carry out one specific step in the arginine synthesis pathway due to a single gene mutation.
  • B: Wild-type Neurospora could grow on minimal medium, demonstrating metabolic independence.
  • C: The three classes of mutants exhibited different growth requirements.
  • D: The arginine pathway was confirmed to operate in Neurospora, similar to mammalian liver cells.

Explanation

The "one gene-one enzyme" hypothesis posits that each gene dictates the production of a single enzyme. The experiment supported this by showing that each class of Neurospora mutants, derived from a single gene mutation, was consistently deficient in one specific step of the arginine biosynthesis pathway, implying a defect in a single corresponding enzyme. Option A directly reflects this link.