Q.What is the shape of TMV? What is its genetic material?

Because viruses do not fit the schemes used for cellular organisms, the International Committee on Taxonomy of Viruses (ICTV) sets the standard rules for naming and classifying them, based on criteria such as the type of nucleic acid a virus carries (DNA or RNA), whether it has an outer envelope, its host range, and - most usefully - the symmetry of its protein coat, the geometric pattern formed by its repeating protein subunits (capsomeres). Helical symmetry arranges capsomeres in a spiral around the nucleic acid, producing a rod-shaped virus, as in TMV; icosahedral (polyhedral) symmetry arranges capsomeres into a near-spherical, many-faced particle, as in many animal viruses; and complex symmetry, seen in bacteriophages, combines both patterns within different parts of one virus particle. …