VIRUS

1
VIRUS
2

• Non living
• Do not grow
• No metabolism
• Do not evolve
• Cause disease in plants and animals
• Do not possess enzymes or organelles
• CAN ONLY REPRODUCE
• If enter a living cell (parasites)

3

• Single particle called a VIRON
• Consists of nucleic acids (DNA or RNA)
• Has protein coat
• Different types
• Icosahedral (20 sides)
• Enclosed in CAPSID
• Some have envelopes
• Some have spike projections
• Herpes, Chicken pox, AIDS, infectious
  mononucleosis

4

• Helical ( spiral)
• Genome (genetic material) in a helix
• Tobacco mosaic (attacks plants), rabies
  (long/oblong), influenza (circular)
• Bacteriophage
• Attacks bacteria
• Has icosahedral head (genome)
• Has tail with rings and fibers
• complex

5
Replication

• Needs living cells to multiply (host)
• Viron attaches to cell membrane and injects
  GENOME into the cell cytoplasm
• Genome directs new viral parts to be synthesized
• cell nucleus and organelles are destroyed
• Viral parts are reconstructed, gt 1000 /hr
• New viruses are released from cell which dies