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#RNA viruses

3 public questions tagged with this topic.

MOLECULAR EVOLUTION

RNA viruses evolve rapidly due to:

High mutation rate reflects key principle in quiz on molecular evolution, where evolutionary mechanisms shape genetic variation and adaptation. In this context, High mutation rate aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why High mutation rate fits helps integrate natural selection, environment.

Ref: Li, Molecular Evolution, Neutral Theory and Molecular Clocks.

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Gene and Genome

Viroids replicate via:

Viroids replicate autonomously using host transcriptional machinery despite lack of protein-coding capacity. Most pospiviroids utilize asymmetric rolling circle mechanism where circular RNA is transcribed by host RNA polymerase II into concatemeric complementary strands cleaved by host RNase and ligated to generate new circles. Chloroplast-replicating avsunviroids use symmetric pathway with self-cleavage via hammerhead ribozyme motifs. No DNA intermediate is involved, distinguishing them from retroviruses. Efficiency depends on RNA structure acting as promoter for Pol II, diverting enzyme from DNA templates to RNA-directed transcription.

Ref: Flores et al., Annu Rev Phytopathology 2005: Viroids Replicate via Rolling Circle Mechanism

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