icosahedral symmetry: most economical way to build symmetric shell, maximal internal volume, with...
TRANSCRIPT
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
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
Name the capsid type:
AdenovirusIcosadeltahedral capsid
EbolaHelical capsid
PoxvirusComplex capsid
Note: Images are not to scale
Poliovirusicosaheral capsid
• 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
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
Potential applications for bacteriophages in human health