Two basic structures of viruses

Two basic structures of viruses

• A. Hollow rod-shaped threads and hollow polyhedrons
• B. Helical and icosahedral
• C. Filamentous and spherical
• D. Capsule and envelope

Answer: (A)

Viruses are primarily classified by the symmetry of their capsid around the genetic material, giving two main structural forms: helical and icosahedral. In helical viruses, the protein subunits arrange themselves into a long, rod-like structure that forms a helix around the nucleic acid. In icosahedral viruses, the capsid is a roughly spherical shell built from many identical subunits arranged to create 20 triangular faces, giving a polyhedral shape. Some viruses may have an outer lipid envelope surrounding the capsid, but this envelope is not what defines the basic structural categories. The other descriptions mix shapes or components that aren’t the fundamental architectural classifications. Filamentous or spherical refer to observed shapes but don’t capture the underlying symmetry, and capsule/envelope describe parts rather than the primary structural forms.

Viruses are primarily classified by the symmetry of their capsid around the genetic material, giving two main structural forms: helical and icosahedral. In helical viruses, the protein subunits arrange themselves into a long, rod-like structure that forms a helix around the nucleic acid. In icosahedral viruses, the capsid is a roughly spherical shell built from many identical subunits arranged to create 20 triangular faces, giving a polyhedral shape. Some viruses may have an outer lipid envelope surrounding the capsid, but this envelope is not what defines the basic structural categories.

The other descriptions mix shapes or components that aren’t the fundamental architectural classifications. Filamentous or spherical refer to observed shapes but don’t capture the underlying symmetry, and capsule/envelope describe parts rather than the primary structural forms.