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Question #46414
The Question
In a metastatic cancer cell line, massive chromosomal rearrangements are observed due to 'illegitimate' homologous recombination between repetitive DNA sequences. Normally, these repetitive sequences are protected from such aberrant recombination by being tightly packed. Which of the following molecular alterations is the most likely primary cause of this specific genomic instability?
Options
- A.
Displacement of the linker histone H1, leading to chromatin decondensation and exposure of repetitive elements.
- B.
Increased binding of Non-Histone Chromosomal (NHC) proteins directly to the nucleosome core particle.
- C.
Extensive methylation of the repetitive DNA sequences, converting euchromatin into heterochromatin.
- D.
Mutation in the histone octamer proteins (H2A, H2B, H3, H4) preventing the formation of the primary 10 nm chromatin fiber.
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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
Nucleosomes|Histone H1|Chromatin Remodeling
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'Histone H1 is the linker histone' but fail to connect its structural role (higher-order condensation) to its functional consequence (sequestering repetitive DNA to prevent aberrant recombination).
The trap lies in distinguishing the specific roles of the histone octamer (primary packaging) versus Histone H1 (secondary condensation and silencing) and understanding that repetitive DNA must be hidden in heterochromatin to maintain genomic integrity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Human Genome Repetitive DNA |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |