Cell Biology MCAT Practice Question
A 45-year-old woman with rheumatoid arthritis is enrolled in a clinical trial testing a novel mitochondrial-targeted therapeutic agent. The drug inhibits opening of the mitochondrial permeability transition pore (mPTP). During in vitro testing of patient-derived immune cells, researchers observe that TNF-α-stimulated apoptosis proceeds normally in drug-treated cells, though the kinetics are slower than in untreated control cells. Caspase-8 activity is detected within minutes of TNF-α exposure in both treated and untreated populations. Which of the following best explains how apoptosis is proceeding in the drug-treated cells?
Answer choices
- ACaspase-9 activation through direct scaffolding by Apaf-1 independent of cytochrome c release
- BAutocrine secretion of death ligands amplifying the extrinsic apoptotic pathway
- CDirect caspase-8-mediated cleavage of caspase-3 via DISC-dependent activationCorrect answer
- DDelayed apoptosis due to compensatory upregulation of anti-apoptotic Bcl-2 proteins
- EConversion to necroptosis through RIPK3-dependent MLKL activation
- FP53-mediated transcriptional induction of pro-apoptotic genes overcoming the mPTP blockade
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