Viruses (AQA A Level Biology)

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Key Features of Viruses

  • Viruses are non-cellular infectious particles that straddle the boundary between ‘living’ and ‘non-living’
  • They are relatively simple in structure; much smaller than prokaryotic cells (with diameters between 20 and 300 nm)
  • Structurally they have:
    • A nucleic acid core (their genomes are either DNA or RNA, and can be single or double-stranded)
    • A protein coat called a ‘capsid’

  • Some viruses have an outer layer called an envelope formed usually from the membrane-phospholipids of a cell they were made in
  • All viruses are parasitic in that they can only reproduce by infecting living cells and using their protein-building machinery (ribosomes) to produce new viral particles

Cell Components- Virus, downloadable AS & A Level Biology revision notes

Viruses are not cellular like prokaryotes and eukaryotes – this is just one example of a virus structure

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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.