Consider a Mutant Organism That Is Unable to Make the Amino

Multiple Choice

Consider a mutant organism that is unable to make the amino acid arginine. Knowing that the metabolic pathway for arginine production is ornithine ->citrulline ->arginine, you test the ability of the mutant to grow in the presence of just one of these compounds. You find that the mutant can grow in the presence of arginine, but not in the presence of citrulline or ornithine. From this, you can conclude that the product of the mutant gene is most directly involved in the production of ____.

A) arginine from ornithine
B) arginine from citrulline
C) citrulline from ornithine
D) ornithine from arginine
E) citrulline from arginine