Need answer for this and must be at least 250 words and must

Need answer for this and must be at least 250 words and must be related to the topic presented below. Please also reference any sources you used (or quoted) at the end of your response. Question: Do we classify viruses as living? Why or why not?

Solution

Viruses are obligate intracellular parasites and are not considered to be true living organisms. A virus is made up of few set of genes within a protective protein shell known as capsid. Some viruses contain another lipid bilayer surrounding the protective protein shell known as envelope. They contain genes made from nucleic acids and a capsid made of smaller subunits called capsomeres. A single virus particle is known as virion. As the primary criteria for a living organism is to reproduce, viruses can only replicate by infecting a host cell. They lack cellular organelles required for their genes to copy, therefore they utilize the host’s cellular machinery to duplicate the genetic information and build new capsids. There are wide varieties of hosts infected by viruses such as eukaryotes which include animals, fungi and plants as well as prokaryotes which include bacteria. A virus infecting bacteria is known as bacteriophage. Secondarily, viruses do not have a cell membrane and cannot metabolise on their own. Viruses usually exist in two different phases. One is the lytic phase in which the viruses actively use the host machinery to replicate in the host cell. And the other is the lysogenic phase in which the viral DNA incorporates into the host cell’s DNA and multiply further. In case of unfavourable nutrient conditions, viruses can switch from lytic phase to lysogenic phase and re-enter into the lytic phase on finding appropriate environmental conditions. Therefore, viruses cannot maintain homeostasis, cannot reproduce on their own, cannot grow and cannot respond to stimuli. They are not dead but are also not real living organisms and can multiply only when present in a host cell.

Countryman J, Gradoville L, Bhaduri-mcintosh S, et al. Stimulus duration and response time independently influence the kinetics of lytic cycle reactivation of Epstein-Barr virus. J Virol. 2009; 83(20):10694-709.

Villarreal L. P. Are viruses alive? Scientific American INC. 2004.