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The "one gene--one enzyme" hypothesis

12/14/2022
Unknown Author

In 1958, George Beadle and Edward Tatum won the Nobel Prize for their study on the relationship between genes and enzymes. They proved through the mutation of Neurospora (a bread mold) that individual genes control specific enzymes. This has been summarized as the "one gene--one enzyme" hypothesis, which is now considered too simplified to accurately depict the relationship between genes and enzymes. However, this hypothesis is remembered as the link connecting two important disciplines: genetics and biochemistry. 

 

 

The experiment:

1) Beadle and Tatum grew Neurospora cells in test tubes with a "complete medium."

2) Then they exposed the Neurospora cells to X-rays and placed them in new tubes under the same conditions. 

3) They waited for the cells to divide and grow. 

4) They transferred some of the cells to a "minimal medium" with a nutrient base of sugar, salts, and biotin. 

5) They observed which cells lived and which died. (This meant that some cells couldn't break down the nutrients in the test tube.)

5) They further tested for different metabolic mutations and, with a lot of experiment repetition, found a different gene mutation connected to each metabolic mutation.

There's a lot more to this experiment, so be sure to check out the additional resources below! 

(Diagram from Khan Academy.) 

Read more about the "one gene, one enzyme" hypothesis: 

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