In this chapter, we focused on the translation of mRNA into proteins as well as on protein structure and function. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations in the chapter, what answers would you propose to the following fundamental questions: How do we know, based on studies of Neurospora nutritional mutations, that one gene specifies one enzyme?

Verified step by step guidance

1. Understand the historical context: The 'one gene, one enzyme' hypothesis was proposed by George Beadle and Edward Tatum based on their experiments with the bread mold Neurospora crassa.
2. Recognize the experimental setup: Beadle and Tatum exposed Neurospora to X-rays to induce mutations and then grew the mutated strains on minimal media to identify nutritional mutants.
3. Identify the key observation: They found that some mutants could not grow on minimal media but could grow when specific nutrients were added, indicating a block in a metabolic pathway.
4. Connect the mutation to enzyme function: Each mutant strain was deficient in a single enzyme required for a specific step in a metabolic pathway, suggesting that each gene encodes a single enzyme.
5. Conclude with the hypothesis: The results led to the formulation of the 'one gene, one enzyme' hypothesis, which posits that each gene is responsible for the production of a single enzyme that affects a single step in a metabolic pathway.

Key Concepts

One Gene-One Enzyme Hypothesis

The One Gene-One Enzyme hypothesis, proposed by George Beadle and Edward Tatum, suggests that each gene within an organism's DNA encodes a specific enzyme that catalyzes a particular biochemical reaction. This concept emerged from experiments with Neurospora crassa, where mutations in specific genes led to the inability to produce certain enzymes, thereby linking genes directly to metabolic functions.

Neurospora crassa as a Model Organism

Neurospora crassa, a type of bread mold, serves as a crucial model organism in genetics due to its simple nutritional requirements and rapid growth. Beadle and Tatum utilized this organism to study the effects of mutations on metabolic pathways, demonstrating how specific genetic alterations could disrupt enzyme production and thus affect the organism's ability to synthesize essential nutrients.

Mutational Analysis

Mutational analysis involves studying the effects of specific genetic mutations on an organism's phenotype, particularly its metabolic capabilities. In the context of Neurospora, researchers induced mutations and observed the resulting nutritional deficiencies, which provided evidence that each mutation corresponded to a loss of function in a specific enzyme, reinforcing the idea that one gene corresponds to one enzyme.