Viruses are made up of nucleic acid (DNA or RNA) enclosed in a protein coat (capsid), which is made up of subunits called capsomeres. Bacterial viruses are called phages.

  1. Tobacco Mosaic Virus has a helical capsid enclosing RNA.

  2. Adenoviruses have a polyhedral capsid with glycoprotein spikes.

  3. Flu viruses have 8 capsids with an RNA genome wrapped in a membranous envelope embedded with glycoproteins.

  4. Phage T4 has a polyhedral head and a tail apparatus.