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Question #45885
The Question
A geneticist designs a PCR experiment to amplify a complete bacterial transcription unit. The forward primer is designed to bind upstream of the promoter, and the reverse primer binds 50 base pairs downstream of the intrinsic (Rho-independent) terminator. Which of the following statements regarding this process is INCORRECT?
Options
- A.
The final PCR amplicon will be longer than the native primary transcript produced in vivo.
- B.
Taq polymerase will prematurely halt synthesis upon encountering the terminator sequence, preventing amplification of the downstream 50 base pairs.
- C.
Unlike the native bacterial DNA polymerase III, the Taq polymerase used in this reaction lacks 3'→5' exonuclease proofreading activity.
- D.
The native RNA polymerase relies on the terminator sequence to dissociate from the template, a mechanism entirely irrelevant to Taq polymerase.
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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
DNA_Polymerase|PCR_Primer|Taq_Polymerase
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often conflate the regulatory boundaries of a gene (promoter/terminator) with physical barriers to all polymerases.
The trap relies on failing to distinguish between the signal-dependent nature of biological transcription (RNA polymerase) and the template-directed, signal-agnostic nature of artificial DNA synthesis (Taq polymerase in PCR).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Transcriptional Unit Boundaries |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |