Viruses are microscopic agents that survive only in the nucleus of cells of other living organisms. This implies that viruses live in any living thing both plants and animals. They replicate inside the cells and, in some advanced cases, they feed on the nucleus of the cells thus resulting in the death of the cells. Viruses have unspecified structure of deoxyribonucleic acid commonly referred to as the DNA (Dilcher, 2000). The DNA defines the structure of cells, the fact that viruses have indefinite DNAs makes them capable of changing their structure from time to time thus making it difficult for the body cells to identify and remove them from the cell structures. Among the most notorious virus is the Human Immunodeficiency virus that causes the Acquired Immune Deficiency Syndrome, AIDS (Nelson, 2010). This research article therefore employs an effective analysis of this single virus to describe the features of other viruses by extension. The structure of a virus A virus is an organism with a simple structure, this is arguably the smallest organism on earth and due to its small size, the organism cannot survive on its own, it thus requires the cell of a host organism to thrive. Viruses have the simplest structures composed of only three components. These are the nucleic acid, the protein coat and the lipid membrane. The nucleic acid is the most essential part of the virus; it contains the deoxyribonucleic and the ribonucleic acids. The two acids define the virus; they contain all the necessary information for the virus to define its unique indefinite structure and to make it multiply (Theodora, Guoying & Dimitris, 2002). The nucleic acid is lightly dispensed in surrounding plasma all of which are enclosed in a protein coat. This is a light layer of pure protein elements that protects the components of the virus. The protein layer defines the virus. However, being purely protein, the coat lacks definite shape to constitute the definite structure of a virus. The soft coat is highly permeable allowing free movement of molecules in and out of the virus. The structure of the protein further changes according to the protein composition of the host cell, this enables the virus to vary its acidity and alkalinity levels to suit that of the host cell thus permit its survival. Besides the two components of a virus is the lipid membrane. This is a layer found after the protein membrane. However most viruses lack this layer and survive only with the protein layer as the most outside coat. Viruses that lack this final outer coat are generally referred to as naked cells. The lipid membrane performs the edge formation function thus defining the virus. It also lacks such strong elements as keratin and lipid and therefore aids in the indefinite structures of viruses. Virus infection process Unlike other living organisms, a virus cannot survive on its own; viruses have no chemical composition to exist without the assistance of a host cell. Host cells on which a virus mounts itself is referred to as a receptor (Agalioti & Prekh, 2001). Viruses choose their receptor carefully taking into consideration the information in the viruse’s deoxyribonucleic and ribonucleic acid this implies that every virus has its specific receptor. Once a virus gains entry into the body of a living organism, they attach themselves to their respective receptor cells from where they thrive through the rigorous replication process (Dilcher, 2000). The flu causing virus shows preference for the mucus coating cells found in the lungs and other airwaves in the body. The HI Virus on the other hand shows indiscriminate preference to white blood cells in the body of a living organism. Since viruses cannot survive alone, they do not therefore freely exist in the environment but are carried in the body cells of other previously infected organisms. They thus transfer from these organisms to the other through contact of the bodies that possibly results in the exposure of the body cells of the second victim. ...Show more
Are Viruses Alive?
Scientists have a compulsive urge to do a few things: meet, argue, categorize things, and drink insane amounts of coffee. I recently found myself ensnared in a very typical argument with my partner: are viruses dead or alive? This is not an unusual event in our relationship — we tend to have epic battles concerning the Middle East, medicine, music, microbes, the cosmos, what animals are the cutest — essentially anything that can be debated ad nauseam for extended periods of time (whilst drinking coffee, of course). Alexis is a first year medical student, and therefore suffering from a disorder that I diagnosed: Medical Student Syndrome. This condition is characterized by the need to discuss all the medical things, all the science things, and all the mysteries of the universe, at all times. And as a scientist, I love to argue, so the relationship is beautifully symbiotic.
The question of whether or not viruses are alive has been hotly debated in the scientific community for many years, so in full disclosure, there is nothing particularly unique about the topic. However, I think it deserves some thought, especially after a long year of Ebola and Measles outbreaks, not to mention the annual influenza events that plague us.
Viruses are an evolutionary enigma, the origins of which are uncertain despite being extensively studied. Researchers have found that nearly every life form has a virus capable of invading it, and viruses appear to be the most ubiquitous biological entity on the planet, outnumbering every other life form combined. And to further complicate matters, viruses have an exhaustive taxonomy, which makes this topic difficult to succinctly discuss.
In the argument of alive vs. dead, it’s important to know what classifies a biological entity as “alive.” For example, a chunk of granite is not living. While it is made up of various elements, it cannot create it’s own energy or reproduce. A cell, however, is capable of reproducing, creating its own energy source, and eventually dying. In 2002, Science magazine published an essay outlining the seven pillars of life, concluding that in order to be categorized as living, the organism must have the following: Program, Improvisation, Compartmentalization, Energy, Regeneration, Adaptability and Seclusion. Simply, these pillars stand for the ability to reproduce and pass genes from one generation to the next, as well as the ability to change in response to environmental demands. Living entities must be compartmentalized in a way that makes chemical reactions possible in order to create energy to sustain vital functions; in addition, they must possess the ability to keep one biological process from causing harm to another biological process (ie, you don’t want to digest vital components of your being). Furthermore, “living” entities must have the ability to regenerate systems after wear and tear (ie, replacement of muscles cells in the heart).
My argument is that viruses are not in fact alive. In brief, viruses are extremely tiny biological agents that require life forms to reproduce and evolve. They infect animals, plants, bacteria, and microorganisms — all of which are known as hosts. They infect by taking up residence in the cells of a host organism where the virus essentially uses the host’s mechanics against the host. In some ways, viruses are almost parasitic hijackers, somewhat alien space invaders. Without a living host cell to replicate in, the virus is nothing but a bit of encapsulated genetic material. This is because viruses are acellular, meaning they do not have cells of their own. It is true that viruses are capable of evolving, but at someone else’s expense. They do not reproduce with one another or by themselves (without the help of a living cell) in order to pass their genes on to another generation.
Alexis’ views are actually not so different from mine, mostly because she admits that she believes that viruses are not necessarily alive in the traditional sense, but they are more living than dead. This is because viruses are equipped with DNA or RNA and are capable of evolving according to natural selection, which is included in the seven pillars of life. A good example of this is the incredible way HIV evolves inside its host to render a single anti-retroviral medication ineffective. It is for this reason that a large cocktail of anti-retroviral drugs is necessary to treat the disease. However, she also views the natural world through a philosophical lens. All organisms have certain requirements for function — on earth, we as humans require oxygen, water and food to thrive, and plants require carbon dioxide, water and sunlight. So she asks, why can’t it just be that viruses require prefabricated cells in order to reproduce in the same way humans need their environment to thrive? And while viruses are metabolically inactive at times, the same is true for seeds, spores and certain types of bacteria. Thus, she argues, viruses just require a different form of environment and enrichment than other living things.
I suppose that I have to concede to a couple of points. First, I agree that viruses are not dead. But I cannot refer to them as living either. While it’s hard to imagine that there could be life on other planets due to the harsh environments and toxic mix of chemicals that exist, there could be organisms that thrive in those settings. Maybe viruses are just ancient aliens living off the inhabitants of Earth. Pondering this makes me think of deep sea organisms that live without sunlight in extremely cold temperatures and survive for millions of years in spite (or because of) these unrelenting conditions. But then I remember, even the creatures living in the deep sea have cells with cell walls and the ability to reproduce on their own in spite of their different requirements for life. The fact remains, viruses don’t even have a chance to be biologically relevant without the cells of another organism, and to me, that doesn’t constitute life.