Various pharmaceutical agents and microbial toxins exert their effects by disrupting highly specific molecular and genetic processes. Match each clinical presentation or drug-induced adverse effect below with the precise underlying molecular mechanism responsible for its pathogenesis.
- An adult hiker experiences fulminant hepatic failure three days after consuming wild mushrooms.Potent inhibition of human RNA polymerase II, resulting in halted mRNA synthesis.
- During multidrug therapy for active tuberculosis, a male patient notes that his urine and tears have turned distinctly orange-red.Selective inhibition of bacterial DNA-dependent RNA polymerase, preventing the initiation of transcription.
- An unvaccinated elementary school child is brought to the emergency department with severe myocarditis and a grayish-white pharyngeal pseudomembrane.Inactivation of human elongation factor 2 (EF-2) via ADP-ribosylation, halting host protein translation.
- While receiving antibiotics for acute pyelonephritis, a patient suffers a sudden and painful Achilles tendon rupture.Inhibition of bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, preventing the relief of DNA supercoiling.
- Following consumption of undercooked hamburger meat, a young girl develops bloody diarrhea and subsequently hemolytic uremic syndrome (HUS).Cleavage of an adenine base from the 28S rRNA of the 60S ribosomal subunit, preventing tRNA binding.
Answer
The correct matches pair each clinical presentation with its specific molecular target: Amatoxin (mushroom ingestion) inhibits human RNA polymerase II; Rifampin (causing orange fluids) inhibits bacterial RNA polymerase; Diphtheria toxin (pseudomembrane) inactivates elongation factor 2; Fluoroquinolones (tendon rupture) inhibit bacterial DNA gyrase; and Shiga-like toxin (EHEC/HUS) cleaves an adenine base from 28S rRNA.
Each correct pairing accurately connects a clinical exposure to its foundational molecular mechanism. Amatoxin (responsible for the hiker's liver failure) inhibits human RNA polymerase II. Rifampin (causing the TB patient's orange fluids) selectively targets bacterial RNA polymerase. Diphtheria exotoxin (causing the child's pseudomembrane) halts translation by inactivating EF-2. Fluoroquinolones (causing the tendon rupture) disrupt DNA replication by blocking bacterial DNA gyrase. Finally, Shiga-like toxin (causing HUS in the young girl) halts protein synthesis by cleaving an adenine from the 28S rRNA.
Step-by-Step Solution
Key Concept
Foundational understanding of molecular genetics requires matching common microbial toxins and pharmacological agents to their specific cellular targets, such as RNA polymerases, topoisomerases, or ribosomal subunits.