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Question #45109
The Question
During the development of a gene therapy protocol for Adenosine Deaminase (ADA) deficiency, researchers utilize a plasmid vector containing a functional ADA cDNA and an ampicillin resistance (ampR) gene for initial cloning in E. coli. However, before packaging the therapeutic gene into a disarmed retroviral vector for human lymphocyte transformation, the ampR gene is deliberately excluded. What is the primary clinical rationale for removing this bacterial selectable marker?
Options
- A.
It eliminates the risk of horizontal gene transfer to the patient's microbiome and prevents potential immunogenic responses against bacterial proteins.
- B.
The bacterial promoter of the ampR gene will competitively bind human RNA polymerase, completely silencing the expression of the therapeutic ADA gene.
- C.
Human lymphocytes lack the specific origin of replication (ori) required to maintain the ampR gene, which triggers immediate apoptosis of the transformed cells.
- D.
The ampR gene induces insertional mutagenesis by specifically directing the retroviral vector to integrate into transcriptionally active human oncogenes.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Selectable Marker vs Cloning Site|Gene Therapy Germline vs Somatic|Plasmid vs Chromosomal DNA
Why This Question Is Tricky
Common Mistakes
The Conceptual Pivot lies in distinguishing between the requirements of 'in vitro' bacterial cloning and 'in vivo' human gene therapy.
Students often memorize that selectable markers are universally 'essential' for genetic engineering (NCERT Chapter 11), failing to realize that introducing bacterial antibiotic resistance genes into a human patient (NCERT Chapter 12) creates massive biosafety and immunological liabilities.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Selectable Marker vs Cloning Site |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |