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VViruses

Packets of DNA or RNA that are not cells — they replicate only inside living hosts.

Also called: Virions ? Obligate intracellular parasites

Coloured illustration of virus particles with geometric capsids
Alexey Solodovnikov (Idea, Producer, CG, Editor), Valeria Arkhipova (Scientific Сonsultant) ? CC BY-SA 4.0

Quick facts

20–300 nm for most; some giant viruses exceed 400 nmTypical size
DNA or RNA, not a free-living cellGenome
1892 — Ivanovsky, tobacco mosaicFirst filterable agent
On the order of 10^31 particles in estimatesEarth abundance
None independent — host ribosomes requiredMetabolism
Do not target virions; they target bacteriaAntibiotics

Viruses are not cells. They are DNA or RNA genomes in protein coats — sometimes wrapped in a stolen membrane — that can make more of themselves only inside a living host.

That host rule explains the whole public story: vaccines train recognition, antibiotics miss the target, and most viral lineages on Earth never notice a human being.

This atlas treats viruses as a branch of the microbial world, not a synonym for 'the worst disease'. Later topics cover phages, vaccines and everyday encounters.

The profile

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  • Familiarity96
  • Medical weight88
  • Benefit25
  • Risk82
  • Research94
  • Live debate55

Risk

82 / 100

Packets of DNA or RNA that are not cells — they replicate only inside living hosts.

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Frequently asked questions

Are viruses alive?
Debated. They evolve and replicate but have no autonomous metabolism. Many biologists call them biological entities, not cells.
Are viruses cells?
No. They lack ribosomes, plasma-membrane growth and division as cells. A virion is a particle.
Do they have DNA or RNA?
Either, depending on the family. The main genome is not both at once in the way a cell keeps DNA and uses RNA.
Why don't antibiotics cure a cold?
Typical colds are viral. Antibiotics hit bacterial walls or ribosomes that virions do not have.
Do all viruses infect humans?
No. Most described viruses infect bacteria, plants, fungi or other animals. Tropism is specific.
How do vaccines relate to viruses?
They present safe signals so immunity recognises a future wild exposure. They are not antibiotics.
Can a virus live on a table forever?
No. Enveloped particles often decay in hours to days depending on material and humidity. Persistence is not immortality.
Is this medical advice?
No. Educational only. Licensed clinicians diagnose and treat infections.

Sources & research

  1. Virus2026 · Wikipedia
  2. WHO: Viral pathogens2024 · WHO

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