Viruses

• Difficult to classify and are not placed under any of the five kingdoms
• Properties of both non-living particles and living organisms
• Characteristics of life

  • Nutrition
  • Response to stimuli
  • Growth
  • Reproduction
  • Respiration
  • Excretion
  • Movement/locomotion
• Only characteristic of life seen in viruses is reproduction, they can only reproduce inside cells of living organisms
• Viruses are acellular, and therefore not classified as prokaryotes or Eukaryotes
• Prokaryotes: Single-celled organisms that lack a nucleus and membrane-bound organelles
• Eukaryotes: organisms with a nucleus and membrane-bound organelles
• Parasites that only reproduce within living cells, obligate intracellular parasites
• obligate: compulsory/ obligated
• intracellular: within a cell
• parasite: an organism that lives on living material (cells) and causes harm
• Viruses are host specific, some are tissue specific
• Viruses reproduce by converting genetic material (DNA or RNA) of host cells into viral nucleic acids so new viruses can be produced