Basic Structure of Viruses

• Viruses are very small (20nm- 450 nm in diameter) and simple in composition
• Nanometer (nm): a metric unit of length equal to one billionth of a meter
• Virus consists of a central nucleic acid surrounded by a protein capsule
• Viruses can infect plant, animal or bacterial cells
• Viruses contain DNA or RNA (never both)
• Some viruses (flu virus) are enclosed by a sheath of lipid and protein molecules called a capsid
• The capsid originates from the host cell's outer membrane
• Viruses are acellular, have no nucleus, cytoplasm or organelles
• Virus shapes varies from rod-shaped, spherical to more complex shapes
• Rod-Shaped Viruses-one of the most common is the TMV-virus (Tobacco Mosaic Virus)

  
• Spherical virus- Adeno virus

  
• Complex virus shapes- Bacteriophage

  
• Basic Structure of a Virus