Viruses

• What do viruses lack that prevents them from fitting the cell theory?

  Cell membrane, cytoplasm, organelles, chromosomes
• How do viruses reproduce?

  With the help of a host cell
• What surrounds the genetic material of a virus?

  A protein coat or capsid
• How many genes does the HIV virus have?

  9 genes
• What is the size of viruses typically measured in?

  Nanometers (nm)
• Why can viruses only be viewed using an electron microscope?


  Because they are extremely small
• What is a virus called when it exists outside a living cell?

  An inert virion
• What happens when viruses invade a cell?

  They take over the cell's metabolism
• What types of organisms can viruses infect?

  Humans, animals, and plants
• What are the key characteristics of viruses?

  • Lack cell membrane, cytoplasm, organelles, chromosomes
  • Require a host cell for reproduction
  • Composed of a protein coat and genetic material
  • Extremely small, measured in nanometers
  • Exist as inert virions outside living cells
  • Cause various infectious diseases