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Question #47732
The Question
In a somatic gene therapy trial for Adenosine Deaminase (ADA) deficiency, a retroviral vector carrying the functional ADA cDNA is introduced into a patient's cultured lymphocytes. To confirm stable integration of the vector into the host genome rather than transient episomal expression, genomic DNA is extracted, digested with a restriction endonuclease that cuts exactly once within the vector sequence, and analyzed via agarose gel electrophoresis and Southern blotting using a vector-specific probe. Which of the following statements regarding this process is INCORRECT?
Options
- A.
A single distinct band corresponding to the exact size of the linearized vector on the autoradiogram indicates that the viral DNA remains unintegrated as an episome.
- B.
Multiple bands of varying molecular weights suggest random stable integration of the retroviral vector into different loci of the host chromosomes.
- C.
Successful stable integration of the vector in these lymphocytes ensures that the functional ADA gene will be transmitted to the patient's offspring, providing a heritable cure.
- D.
If undigested genomic DNA is electrophoresed, the unintegrated viral vectors will migrate much faster through the agarose matrix than the high molecular weight host chromosomal DNA.
Check Your Answer
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
Genetic_Code_Degeneracy|Ori_Sequence_Stringency|Taq_Polymerase_Thermal_Stability
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The trap relies on conflating 'stable chromosomal integration' with 'heritability'.
Students often mistakenly assume that if a therapeutic gene is permanently integrated into a patient's DNA, it becomes a permanent cure for their lineage.
However, NCERT strictly distinguishes between somatic cell therapy (like ADA lymphocyte treatment, which is non-heritable) and germline therapy.
The question also rigorously tests the applied principles of gel electrophoresis and restriction digestion in analyzing viral vector integrity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Ori Sequence Stringency |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |