Viruses Flashcards

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1
Q

How were viruses discovered

A

Tobacco plants can suffer from mosaic disease which attacks their leaves causing them to die. In 1900 a scientist carried out an investigation and since the disease was caused by something smaller than a bacteria, the scientist called it a virus

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2
Q

Characteristics of viruses

A
  1. Viruses are extremely small - they can only be seen with an electron microscope
  2. Have two distinct states: a virus (when active, and a virion (when dormant and not in contact with a host cell)
  3. Not living organisms
  4. Can only survive inside the cells of living organisms
  5. Can only reproduce inside a living cell
  6. Viruses can remain in a dormant state
  7. Various shapes
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3
Q

Different shapes of viruses

A
  1. Polyhedral: has twenty triangular faces
  2. Helical: resembles a coiled spring
  3. Complex: has a head, sheath and tail fibres
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4
Q

Structure of viruses

A
  • viruses are acellular, it is not a cell (has no nucleus, cytoplasm or organelles)
  • has a core of DNA or RNA, can’t be both
  • nucleic acid is surrounded by a protein coat or capsid
  • some can be covered by an envelope of a lipid bilayer
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