question_answer

An organism is able to survive on a culture medium, containing nutrient A, by the following enzyme - catalysed reactions.

\[A\xrightarrow{P}B\xrightarrow{q}C\xrightarrow{r}D\]

A mutant organism failed to survive on this medium, but grew well when nutrient C was added to it.

(i) Which gene of this mutant organism is defective and what does such a condition indicate?

(ii) Mention the major components and their functions in an operon.

Answer:

(i) The gene p is defective and it indicates that one gene controls the synthesis of other enzyme.

(ii) An operon has the following components

(a) Structural gene(s) which transcribes the mRNA for the protein synthesis.

(b) An operator gene, which controls the structural gene(s) as a unit.

(c) A promoter gene, where the RNA polymerase binds for transcription.