[Campbell Biology P.386] The experiments conducted by Beadle and Tatum, later supported by S... | Practice Question

The experiments conducted by Beadle and Tatum, later supported by Srb and Horowitz, led to the formulation of the "one gene-one enzyme hypothesis." Which finding was crucial for supporting this hypothesis?

  • A: All proteins are enzymes.
  • B: Mutant strains of Neurospora each lacked a specific enzyme that catalyzed a blocked step in a biochemical pathway.
  • C: Genes directly build proteins.
  • D: Genes can code for multiple unrelated polypeptides via alternative splicing.

Explanation

The passage states: 'These results, and those of many similar experiments done by Beadle and Tatum, suggested that each class was blocked at a different step in this pathway because mutants in that class lacked the enzyme that catalyzes the blocked step.' This directly supports the 'one gene-one enzyme' hypothesis by showing a direct link between a gene mutation, a missing enzyme, and a blocked biochemical pathway.