This paper is arguing that viruses should not be considered as 'alive.'
Christina Arcidiacono
BIO 110
September 2011
Are Viruses Alive? I Think Not.
A question that has been asked for generations and generations turns out to not have the most clear cut easy answer, but is comprised with much supporting evidence leading towards one theory. This renowned question is; whether or not a virus is considered a living organism or not. Many consider this question to be controversial because some believe that viruses fit into the criteria of a living organism, while others don’t. A living organism is defined as something that is organized, acquire materials and energy, reproduce, respond, homeostatic, grow/ develop, and have the capability to adapt (Mader and Windelspecht 2011). Whereas a virus can be defined as “an infectious agent that replicates only within the cells of living hosts” (Dictionary.com, 2011). Unlike cells, viruses cannot grow and develop on their own. In the same manner, viruses do not have the ability to reproduce on their own without the help of a host cell. As stated in the definition of a living organism, they must be able to maintain homeostasis, which yet again, viruses cannot do without the host cell. Viruses should not be considered alive because though they may have the ability to maintain characteristics of a living organism, it would not be possible without infecting a host cell.
Within the spectrum of living organisms, the cell is considered to be the smallest unit of life, this is because every living being is built of cells (Mader and Windelspecht 2011). One characteristic of a living organism is that it can grow and develop overtime, therefore with evolution all living things can be traced back to one common ancestor. All living things are traced back to the common ancestor, LUCA, which is “the being to which all living organisms can trace their family trees” (Judson 2009). According to Judson, (2009), “the tree of life only covers cell-based life forms”, and Rancaniello, (2009), notes that “viruses cannot be included in the tree of life because they do not share characteristics with cells”. There is also a concept called ‘membrane heredity’ which refers to the fact that cells in our environment today have inherited membranes from some of the first cells that ever evolved. Each cell is derived from another cell, proving ancestry and development, unlike viruses. Therefore, this evidence demonstrates the fact that viruses do not grow and develop overtime and do not have a history of ancestors as cells do.
In order to be classified as living, the organism must be able to reproduce. A virus that is not within the cell of a living organism does not have the ability to reproduce on its own. When a virus infects the cell of a ‘proper organism,’ they then can reproduce and make more viruses (Judson 2009). Although they do maintain the ability to consequently reproduce, it is only under certain conditions and would not be able to happen without the living cell. In all living organisms, the genes are made up of DNA and is where the genetic material is stored (Mader and Windelspecht 2011), whereas with viruses, only some maintain DNA, but more often they have RNA where their genetic information is stored (Judson 2009). When living organisms reproduce, the DNA is passed on and provides the ‘blueprint’ for the organization and metabolism of that individual organism (Mader and Windelspecht 2011). Without infecting a host cell, the virus is unable to reproduce on their own, therefore not fulfilling the characteristic of a living organism, which is reproduction.
A very important characteristic of a living organism is the ability to maintain homeostasis. This refers to the cell’s capability to maintain an internal environment (Mader and Windelspecht 2011). All living organisms are metabolic which means that they are able to undergo chemical reactions within the cell (Mader and Windelspecht 2011). Though, without the maintenance of homeostasis, the organism cannot maintain its metabolism. Viruses are like a parasite in that they get all biomolecular aspects of life from their host (Villarreal 2004). Without infecting a host, a virus is unable to maintain the characteristics of metabolism and homeostatsis, which are essential to being classified as a living organism. As stated earlier, although they do have the capability once they are within the host cell to complete functions of a living organism, the fact that they cannot do it on their own provides evidence that they are not living.
When confronted with the question as to whether or not viruses are living, it seems that the answer is fairly clear and well supported. Viruses are not living because they do not fit into the criteria of a living organism when they are in their individual form. Viruses are parasites and they depend on the host for all raw materials and energy necessary for functions from reproduction and evolution to all biochemical activities (Villarreal 2004). As far as classification, it seems that viruses should not be considered as living but rather under the same classifications as parasites. A parasite is an organism that lives in or on another organism (Merriam-Webster 2011), and therefore benefits from that particular host. Therefore, it makes perfect sense for viruses to be classified as parasites because if it was not for the host cells, viruses would not be able to perform characteristics of a living organism at all.
References
Mader S, Windelspecht M. 2012. Essentials of Biology. New York (NY): McGraw-Hill
Judson O. [home page on the Internet]. 2009. [A Gazillion Tiny Avatars; cited n.d.]. Available from: http://opinionator.blogs.nytimes.com/2009/1215/a-gazillion-tiny-avatars/.
Racaniello V. [home page on the Internet]. 2009 Mar. 19. [Viruses and the Tree of Life; cited n.d.]. Available from: http://www.virology.ws/2009/03/19/viruses-and-the-tree-of-life/.
Villareal L. [home page on the Internet]. 2004 Dec.. [Are Viruses Alive?; cited n.d.]. Available from: http://www.uvm.edu/~biology/Classes/011/alive.pdf.
Merriam-Webster. Merriam-Webster Dictionary. 2011. Available from: http://m-w.com.
Dictionary.com. Dictionary.com, LLC; 2011. Available from: http://dictionary.reference.com/browse/virus
BIO 110
September 2011
Are Viruses Alive? I Think Not.
A question that has been asked for generations and generations turns out to not have the most clear cut easy answer, but is comprised with much supporting evidence leading towards one theory. This renowned question is; whether or not a virus is considered a living organism or not. Many consider this question to be controversial because some believe that viruses fit into the criteria of a living organism, while others don’t. A living organism is defined as something that is organized, acquire materials and energy, reproduce, respond, homeostatic, grow/ develop, and have the capability to adapt (Mader and Windelspecht 2011). Whereas a virus can be defined as “an infectious agent that replicates only within the cells of living hosts” (Dictionary.com, 2011). Unlike cells, viruses cannot grow and develop on their own. In the same manner, viruses do not have the ability to reproduce on their own without the help of a host cell. As stated in the definition of a living organism, they must be able to maintain homeostasis, which yet again, viruses cannot do without the host cell. Viruses should not be considered alive because though they may have the ability to maintain characteristics of a living organism, it would not be possible without infecting a host cell.
Within the spectrum of living organisms, the cell is considered to be the smallest unit of life, this is because every living being is built of cells (Mader and Windelspecht 2011). One characteristic of a living organism is that it can grow and develop overtime, therefore with evolution all living things can be traced back to one common ancestor. All living things are traced back to the common ancestor, LUCA, which is “the being to which all living organisms can trace their family trees” (Judson 2009). According to Judson, (2009), “the tree of life only covers cell-based life forms”, and Rancaniello, (2009), notes that “viruses cannot be included in the tree of life because they do not share characteristics with cells”. There is also a concept called ‘membrane heredity’ which refers to the fact that cells in our environment today have inherited membranes from some of the first cells that ever evolved. Each cell is derived from another cell, proving ancestry and development, unlike viruses. Therefore, this evidence demonstrates the fact that viruses do not grow and develop overtime and do not have a history of ancestors as cells do.
In order to be classified as living, the organism must be able to reproduce. A virus that is not within the cell of a living organism does not have the ability to reproduce on its own. When a virus infects the cell of a ‘proper organism,’ they then can reproduce and make more viruses (Judson 2009). Although they do maintain the ability to consequently reproduce, it is only under certain conditions and would not be able to happen without the living cell. In all living organisms, the genes are made up of DNA and is where the genetic material is stored (Mader and Windelspecht 2011), whereas with viruses, only some maintain DNA, but more often they have RNA where their genetic information is stored (Judson 2009). When living organisms reproduce, the DNA is passed on and provides the ‘blueprint’ for the organization and metabolism of that individual organism (Mader and Windelspecht 2011). Without infecting a host cell, the virus is unable to reproduce on their own, therefore not fulfilling the characteristic of a living organism, which is reproduction.
A very important characteristic of a living organism is the ability to maintain homeostasis. This refers to the cell’s capability to maintain an internal environment (Mader and Windelspecht 2011). All living organisms are metabolic which means that they are able to undergo chemical reactions within the cell (Mader and Windelspecht 2011). Though, without the maintenance of homeostasis, the organism cannot maintain its metabolism. Viruses are like a parasite in that they get all biomolecular aspects of life from their host (Villarreal 2004). Without infecting a host, a virus is unable to maintain the characteristics of metabolism and homeostatsis, which are essential to being classified as a living organism. As stated earlier, although they do have the capability once they are within the host cell to complete functions of a living organism, the fact that they cannot do it on their own provides evidence that they are not living.
When confronted with the question as to whether or not viruses are living, it seems that the answer is fairly clear and well supported. Viruses are not living because they do not fit into the criteria of a living organism when they are in their individual form. Viruses are parasites and they depend on the host for all raw materials and energy necessary for functions from reproduction and evolution to all biochemical activities (Villarreal 2004). As far as classification, it seems that viruses should not be considered as living but rather under the same classifications as parasites. A parasite is an organism that lives in or on another organism (Merriam-Webster 2011), and therefore benefits from that particular host. Therefore, it makes perfect sense for viruses to be classified as parasites because if it was not for the host cells, viruses would not be able to perform characteristics of a living organism at all.
References
Mader S, Windelspecht M. 2012. Essentials of Biology. New York (NY): McGraw-Hill
Judson O. [home page on the Internet]. 2009. [A Gazillion Tiny Avatars; cited n.d.]. Available from: http://opinionator.blogs.nytimes.com/2009/1215/a-gazillion-tiny-avatars/.
Racaniello V. [home page on the Internet]. 2009 Mar. 19. [Viruses and the Tree of Life; cited n.d.]. Available from: http://www.virology.ws/2009/03/19/viruses-and-the-tree-of-life/.
Villareal L. [home page on the Internet]. 2004 Dec.. [Are Viruses Alive?; cited n.d.]. Available from: http://www.uvm.edu/~biology/Classes/011/alive.pdf.
Merriam-Webster. Merriam-Webster Dictionary. 2011. Available from: http://m-w.com.
Dictionary.com. Dictionary.com, LLC; 2011. Available from: http://dictionary.reference.com/browse/virus