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Question #45246
The Question
During the large-scale production of a recombinant protein in a continuous culture bioreactor, the product yield suddenly drops, and the recovered protein is found to be heavily degraded during the elution phase of downstream processing. Molecular analysis reveals that an unintended transcription factor caused transcriptional stalling. Which of the following best explains the molecular basis of this stalling and its cascading effect on downstream processing?
Options
- A.
The factor bound to the coding strand (3' → 5'), halting mRNA synthesis, which caused a toxic metabolic flux that altered the pH and denatured the protein during elution.
- B.
The factor compromised the utility of the non-coding strand (3' → 5') as a template, halting transcription; the resulting metabolic imbalance shifted the bioreactor's pH, degrading the protein during downstream processing.
- C.
The factor bound to the non-coding strand (5' → 3'), preventing the binding of RNA polymerase, which led to the accumulation of toxic byproducts that inhibited the elution of DNA from the agarose gel.
- D.
The factor stalled translation on the coding strand (3' → 5'), causing a buildup of incomplete polypeptides that altered the ionic strength of the elution buffer.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Elution Process|Non-Coding Strand Utility|Downstream Processing
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The nomenclature of DNA strands during transcription.
Students frequently fall for the 'Word-Play' trap, assuming the 'non-coding' strand is useless.
In reality, the non-coding strand (3' → 5') is the vital template strand.
The question also tests the ability to synthesize concepts across two NCERT chapters: Molecular Basis of Inheritance (Transcription polarities) and Biotechnology (Bioreactor steady-state and Downstream Processing sensitivity to pH/ionic shifts).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Metabolic Flux and Steady State |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |