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Question #45789
The Question
A researcher uses RNA interference (RNAi) to specifically silence the gene encoding the protein dystrophin in a culture of mature human skeletal muscle fibers. If these muscle fibers are subsequently stimulated in a physiological medium containing abundant calcium ions and ATP, which of the following best describes the immediate cellular consequence?
Options
- A.
Calcium fails to bind to the TpC subunit of troponin, preventing the unmasking of myosin-binding sites on F-actin.
- B.
The Z-lines fail to anchor the thin filaments, leading to the immediate structural collapse of the sarcomere during contraction.
- C.
Sarcomere shortening occurs via normal cross-bridge cycling, but force transmission to the sarcolemma is impaired, causing membrane damage.
- D.
The hydrolysis of ATP by the heavy meromyosin (HMM) head is inhibited, preventing the execution of the power stroke.
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
Sarcomere_Functional_Boundaries|RNA_Interference_Mechanism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the structural proteins involved in active contraction (actin, myosin, troponin, tropomyosin) with those involved in force transmission and structural integrity (dystrophin).
The trap assumes that a genetic defect causing 'muscular dystrophy' directly halts the sliding filament mechanism, whereas it actually causes secondary mechanical damage due to decoupled force transmission.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Locomotion and Movement - Class 11 |
| Concept | Sliding Filament Theory Mechanics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |