The debate on the status of virus is still very much alive. Viruses represent the nature’s simplest organization just RNA or DNA and a protein coat that exhibits some properties of life.
Viruses are obligate intracellular parasites that consist of DNA or RNA as genetic material surrounded by a protein coat.
Why viruses are considered living or borderline between living and non living objects?
1. They possess genetic material (DNA or RNA) and proteins
2. Inherent potential for replication inside the host
3. They can undergo multiplication and mutation
4. Viruses behave as intracellular obligate parasites. Within the host, they use the replication machinery of the host to replicate its genome and to synthesize its protein coat
5. Crystallised viruses very well preserve their properties of ‘life’ or living properties.
6. Viruses respond to chemicals, heat and radiations
7. Viruses has the ability to transmit from infected hosts to uninfected ones
Why viruses are considered as non living?
1. Inability to exhibit properties of life outside living host cells
2. Outside living cells viruses are inert particles that can even be crystallized ( e.g., Tobacco Mosaic Virus)
3. Absence of protoplasm (the living component of the cell), cellular organization, cell organelles, metabolic reactions etc
4. Viruses can replicate and multiply inside the host but cannot grow
5. Viral replication is different from reproduction of other living organisms
What is the minimum requirement for creating “life”?
Genetic material (RNA/DNA) and proteins and that is what we learned from virus.
Undoubtedly, viruses represent the simplest organisation that exhibits some qualities of life.