Which of the following organism requires tryptophan for growth –
**Core Concept**
The question is testing the student's knowledge of auxotrophic requirements of various microorganisms. Tryptophan is an essential amino acid, and some organisms require it for growth as they cannot synthesize it on their own.
**Why the Correct Answer is Right**
The correct answer is a type of organism that lacks the enzyme anthranilate synthase, which is necessary for the biosynthesis of tryptophan. This enzyme catalyzes the condensation of chorismate and glutamine to form anthranilate, a key intermediate in the tryptophan biosynthesis pathway. As a result, this organism requires tryptophan as an external source for growth.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not require tryptophan for growth. It can synthesize tryptophan on its own.
**Option B:** This option is incorrect because it requires a different amino acid for growth, not tryptophan.
**Option C:** This option is incorrect because it does not require tryptophan for growth. It can synthesize tryptophan on its own.
**Clinical Pearl / High-Yield Fact**
Tryptophan is an essential amino acid that plays a crucial role in protein synthesis, neurotransmitter production, and energy metabolism. Some organisms, like the correct answer, require tryptophan as an external source for growth, highlighting the importance of this amino acid in various biological processes.
**Correct Answer:** C.