Biology Acellular Life SZABMU 2023
PMDC Verified Question 26 of 70
Choose the entities which requires a single cellular gene to encode the protein making up the organism:
A
Viroid
B
Virion
C
Virus
D
Prions
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Prions
Concept:

Subviral agents and their genetic basis.

Solution:

  • Prions are proteinaceous infectious particles completely devoid of nucleic acid.
  • The structural protein making up a prion (\(\text{PrP}\)) is encoded by a single cellular gene (the PRNP gene) located in the host's own cellular genome.
  • The normal cellular protein (\(\text{PrP}^\text{C}\)) undergoes conformational misfolding into the infectious, \(\beta\)-sheet rich scrapie isoform (\(\text{PrP}^\text{Sc}\)), which then induces further normal host protein molecules to misfold.
  • Therefore, Prions require a single cellular host gene to encode their protein.


Why other options are incorrect:

  • A (Viroid): Viroids consist solely of tiny, naked circular RNA molecules and possess no protein coat (they do not encode or contain any protein).
  • B & C (Virion / Virus): Viruses contain their own viral genome encoding multiple distinct proteins (capsid capsomeres, enzymes, envelope proteins), not a single cellular host gene.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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