1. Icosahedral Symmetry: Most economical way to build symmetric shell, maximal internal volume, with nonsymmetric proteins: icosahedron Icosahedron: solid with 20 faces, each an equilateral triangle, approximates a sphere Icosadeltahedral capsids Found in larger viruses Shape similar to a soccer ball

2. Helical Symmetry: Less defined shape or structure Rod-shaped capsomers directly coat the nucleic acid Assemble into helical nucleocapsid ALL human viruses with this capsid type are enveloped

3. Name the capsid type: Adenovirus Icosadeltahedral capsid Ebola Helical capsid Poxvirus Complex capsid Note: Images are not to scale Poliovirus icosaheral capsid

4. Range in size from 24-200 nm in length Contain a head structure, which can vary in size and shape The head encloses nucleic acid and acts as the protective covering Some phages have tails attached to the phage head At the end of the tail, phages like T4 have a base plate and one or more tail fibers attached to it. Bacteriophage

5. Significance of phages include: Carry virulence factors for certain bacteria Essential members of the ecosystem Contributions to understanding genetics and molecular biology Phage as Tools

6. Potential applications for bacteriophages in human health