Question

How do viruses relate to the characteristics of life?

Answer 1

Hint: Russian botanist D.J. Iwanowski (1892) first discovered a virus in an infected tobacco plant but M.W. Beijerink (1898) coined the term virus. Then American chemist W.M. Stanley (1935) isolated the pure crystal of Tobacco Mosaic Viruses (TMV) and concluded that viruses are made of nucleoproteins.

Complete answer:
Although viruses are known to be connecting links between living and nonliving, they do not seem to have any characteristics of life. They do not grow or develop, cannot reproduce on their own, and do not require energy for their survival. Viruses are cellular, non-cytoplasmic infectious agents that are smaller than bacteria. These host-specific organisms transmit diseases to healthy organisms.
Structurally viruses consist of a protein coat and genetic material within. The genetic material is either DNA or RNA which helps the virus enter the host cell and integrate itself into the host genome. All viruses are obligate parasites and thus utilize the host machinery to reproduce itself. All parts of the virus are manufactured within the host cell. The virus particles are then released either by lysis or lysogeny.
Viruses have commercial applications like vaccine production or as vectors. In such cases, they are effective in small doses and highly resistant to extreme physical conditions.
Certain characteristics similar to those observed in living organisms are also seen in viruses. As in normal living cells, these also contain proteins and glycoproteins. They can evolve to adapt to their hosts.

Note: Viruses either follow the lytic or lysogenic life cycle. In the lytic cycle, the viruses burst out of the host cell whereas in the lysogenic cycle the viruses survive and replicate within the host cell.