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Question #47704
The Question
During a recombinant DNA experiment, a researcher mistakenly uses a restriction endonuclease that cleaves exclusively within the ori (origin of replication) sequence of a cloning vector, rather than the multiple cloning site (MCS). After ligating the alien DNA into this site and introducing the vector into competent E. coli cells, the culture is plated on an agar medium containing the appropriate antibiotic. Which of the following best describes the expected outcome?
Options
- A.
Abundant recombinant colonies will appear, but they will exhibit a very low copy number due to the altered ori sequence.
- B.
No colonies will grow on the selective medium because the insertional inactivation of the ori prevents the autonomous replication and maintenance of the plasmid.
- C.
Only non-recombinant colonies will grow because the alien DNA will be excised by the host's DNA repair mechanisms to restore the ori.
- D.
The transformants will grow normally, but they will fail to express the cloned gene because the ori also acts as the primary promoter for transcription.
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
EcoRI | Taq Polymerase | PCR Primer Design
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often associate 'insertional inactivation' exclusively with selectable markers (like beta-galactosidase or antibiotic resistance genes) used for screening recombinants.
This question tests the application of the same physical principle to the ori sequence.
If the ori is disrupted, the vector loses its defining characteristic—autonomous replication—rendering the entire transformation process functionally void, mimicking a failure of antibiotic selection.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Restriction Endonuclease Nomenclature |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |