Question

Which of the following changes in a vector is used to increase the yield of protein produced in recombinant protein synthesis?

• A. Inducible promoter
• B. Genes for protease inhibitors
• C. Translation initiation
• D. Translation and transcription termination

Hint:

Yield depends on a controllable switch that turns transcription on at high cell density.

Answer 1

The Correct Option is A

The amount of a recombinant protein that a cell makes is governed first and foremost by how much messenger RNA is transcribed from the cloned gene, and transcription is controlled by the promoter placed ahead of that gene in the vector. To get the largest possible output, engineers fit the vector with an inducible promoter rather than a constitutive one. With an inducible system, the bacteria are first allowed to multiply to a high density while the foreign gene stays silent, sparing the cells the metabolic cost and toxicity of overexpression. An inducer such as IPTG is then added, throwing the promoter switch and triggering a massive, synchronized wave of transcription and protein synthesis. Adding protease inhibitor genes would only slow degradation, and adjusting translation start or stop signals addresses correctness of synthesis rather than overall quantity. Hence the deliberate vector modification that raises yield is the use of a strong inducible promoter. \[\boxed{\text{Inducible promoter}}\]