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Question #45878
The Question
In an experimental E. coli culture, a mutation specifically inactivates the 5' → 3' exonuclease activity of DNA Polymerase I. Which of the following will be the most direct consequence of this mutation during the replication of its circular genome?
Options
- A.
The lagging strand will consist of Okazaki fragments that cannot be joined by DNA ligase due to the persistence of RNA primers.
- B.
DNA Polymerase III will fail to add deoxyribonucleotides to the free 3'-OH end of the RNA primers.
- C.
The replication fork will fail to proceed bidirectionally from the ori site, leading to severe topological stress.
- D.
The leading strand will be synthesized discontinuously, as it will require multiple RNA primers to bypass the mutation.
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
DNA Polymerase Directionality|DNA Ligase Polarity|Plasmid vs Chromosomal DNA
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the specific roles of DNA Polymerase I, III, and Ligase.
A common misconception is that DNA Ligase can join Okazaki fragments regardless of primer removal.
This question tests the sequential dependency of lagging strand maturation: primer excision by Pol I must precede ligation by DNA Ligase.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | DNA Polymerase Directionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |