Molecular Biology/Genetics USMLE Step 1 Practice Question
A 58-year-old woman with a newly diagnosed breast cancer presents with a palpable 2.5-cm mass. Vital signs show BP 128/82, HR 92, RR 16, Temp 37.1°C, SpO2 98%. Tumor biopsy reveals marked overexpression of an oncogenic mRNA with elevated HER2 protein levels on immunohistochemistry. Genetic analysis shows absence of a specific small endogenous RNA that normally suppresses this mRNA's translation. She denies recent weight loss. Which molecule is most directly involved in this normal posttranscriptional silencing mechanism?
Answer choices
- ASmall nuclear ribonucleoprotein in the spliceosome only
- BDNA primase
- CTelomerase RNA template
- DTopoisomerase II
- EMicroRNA incorporated into the RNA induced silencing complexCorrect answer
- FLong non-coding RNA bound to chromatin remodeling complexes
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