Give a brief account of viruses with respect to their structure and the nature of genetic material. Also, name four common viral diseases.
Viruses have the following characteristics: (i) All plant viruses have single-stranded RNA and all animal viruses have either single or double-stranded RNA or double-stranded DNA. (ii) Protein vims also contain genetic material RNA or DNA. A vims is a nucleoprotein and the genetic material is infectious, These are obligate parasites, self replicating, non-cellular organisms. (iii) Vimses are smaller than bacteria and their genetic material is surrounded by protein I coat called capsid. Capsid is made up of small subunits called capsomeres. Four common viral diseases are : (a) Cough and cold (b) Mumps (c) Influenza (d) Smallpox
