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Question #46776
The Question
Centromeric regions of eukaryotic chromosomes consist of highly repetitive satellite DNA (heterochromatin) that replicates late in the S-phase. If a cell experiences severe replication stress causing DNA ligase to fail specifically during this late replication period, which of the following cytological events will most likely be observed during the subsequent M-phase?
Options
- A.
Arrest at the G1/S checkpoint due to the accumulation of single-stranded DNA on the leading strand.
- B.
Formation of anaphase bridges due to the inability to join Okazaki fragments on the lagging strand.
- C.
Non-disjunction during Anaphase due to the failure of DNA polymerase to synthesize in the 3' to 5' direction.
- D.
Premature chromosome condensation in Prophase due to the absence of RNA primers in the euchromatin.
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
Centromere Positionality|DNA Polymerase Directionality|DNA Ligase Polarity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the isolated function of DNA ligase (joining Okazaki fragments) but fail to synthesize its cytological consequence during cell division.
The trap lies in distinguishing between replication errors (which cause structural aberrations like anaphase bridges) and spindle errors (which cause numerical aberrations like non-disjunction).
Furthermore, it tests the NCERT fact that DNA polymerase only polymerizes in the 5' to 3' direction, making Option C a classic distractor.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Centromere Positionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |