In Beadle and Tatum\'s study of Neurospora , they were able to identify three cl
ID: 16104 • Letter: I
Question
In Beadle and Tatum's study of Neurospora , they were able to identify three classes of arginine auxotrophs, mutants that needed arginine added to minimal media in order to grow. The pathway in the production of arginine includes the following steps: precursor ornithine citrulline arginine. What nutrient(s) had to be added to the minimal medium in order for the class of mutant with a defective enzyme for the precursor ornithine step to grow?citrulline only
precursor only
precursor, ornithine, and citrulline
ornithine or citrulline
Explanation / Answer
The Ornithine has to to be added to the minimal medium in order for the class of mutant with a defective enzyme for the precursor ornithine step to grow. Because same supplement satisfies the growth requirement of the each mutant. In case of arginine, citrulline or ornithine has to be used as supplement. Precursor is need for intitiation of the reaction but without the same supplement of ornithine, step will not grow.
Hence the correct answer is ornithine only.