Before You Begin
Question #47736
The Question
During a recombinant DNA experiment, a researcher amplifies a gene of interest using Taq polymerase, separates the products via agarose gel electrophoresis, and recovers the DNA through elution. Due to the lack of 3'→5' proofreading activity in Taq polymerase, several truncated DNA artifacts are generated and co-eluted. If these artifacts are successfully ligated into the multiple cloning site of a pUC vector, what will be the most likely outcome during Blue-White screening on an X-gal medium?
Options
- A.
The artifacts will fail to inactivate the lacZ gene, producing blue colonies that represent true recombinants.
- B.
The artifacts will cause insertional inactivation of the lacZ gene, producing white colonies that act as false positives.
- C.
The artifacts will induce α-complementation, resulting in blue colonies that act as false positives.
- D.
The artifacts will disrupt the ampR gene instead of the lacZ gene, preventing the growth of any colonies.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
VNTR|Restriction_Fragments|Genetic_Data_Storage
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often rote-memorize 'White colonies = Successful Recombinants' without understanding the underlying mechanism.
The trap exploits the assumption that a white colony guarantees the presence of the target gene.
In reality, insertional inactivation only confirms that some DNA fragment (even a truncated PCR artifact) has disrupted the lacZ gene, highlighting the functional consequence of Taq polymerase's lack of proofreading.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Gel Electrophoresis Migration |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |