Difficulty: Easy
Correct Answer: translation is inhibited by diphtheria toxin
Explanation:
Introduction / Context:Archaea share several molecular features with Eukarya despite their prokaryotic cell organization. One well-tested distinction in exams is sensitivity of the translational machinery to specific inhibitors such as diphtheria toxin.
Given Data / Assumptions:
Concept / Approach:Diphtheria toxin inactivates eukaryotic-type elongation factor (EF-2). Archaeal translation factors and ribosomal components resemble eukaryotic counterparts more than bacterial ones, making archaeal translation similarly sensitive. In contrast, Bacteria use EF-G and are not inhibited by the toxin.
Step-by-Step Solution:
Evaluate coupling: Eukarya have a nucleus; transcription and translation are not coupled. Archaea (like bacteria) can couple these processes. Therefore option A is not true for both.Assess initiator tRNA: Formyl-methionine is bacterial; eukaryotes and archaea initiate with methionine (no formyl group). Hence option D is incorrect.Check amino acid chirality: Proteins universally use L-amino acids, not D. So option C is false.Diphtheria toxin sensitivity aligns with archaeal/eukaryotic translation factors. Option B is correct.Verification / Alternative check:Compare the composition of ribosomal proteins and initiation/elongation factors across domains—archaeal factors cluster with eukaryotic homologs phylogenetically.
Why Other Options Are Wrong:A: Not true for eukaryotes. C: Contradicts universal L-amino acid usage. D: fMet is bacterial only.
Common Pitfalls:Assuming all prokaryotes share bacterial-like translation features; Archaea often align with Eukarya in core information-processing proteins.
Final Answer:translation is inhibited by diphtheria toxin
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