Not all computer viruses are destructive though. Bogdana Mojarov Pundit. Do Viruses think? They can think. They do things that we do not expect. Once in, viruses commandeer the cell's nucleic acid and protein-making machinery, so that more copies of the virus can be made.
Jingjing Himmeldirk Pundit. Are viruses living or nonliving and why? Viruses are not living things. Viruses are complicated assemblies of molecules, including proteins, nucleic acids, lipids, and carbohydrates, but on their own they can do nothing until they enter a living cell. Without cells, viruses would not be able to multiply. Therefore, viruses are not living things.
Phillis Guilarte Teacher. What are bacteria made of? Bacteria do not have a membrane-bound nucleus, and their genetic material is typically a single circular bacterial chromosome of DNA located in the cytoplasm in an irregularly shaped body called the nucleoid. The nucleoid contains the chromosome with its associated proteins and RNA.
Jacomar Kleinebekel Teacher. How do we classify viruses? Virus classification. Virus classification is the process of naming viruses and placing them into a taxonomic system. Viruses are mainly classified by phenotypic characteristics, such as morphology, nucleic acid type, mode of replication, host organisms, and the type of disease they cause. Lihong Olenev Teacher. Can viruses grow? How does a virus grow? Viruses cannot eat food or grow on their own, but they can make more of themselves if they live inside the cells of other organisms, called "hosts".
The viruses attack those host cells and make more of themselves. Then the viruses move on to other host cells and do it all over again. Celedonio Galeas Teacher. What do viruses need to reproduce? Viruses depend on the host cells that they infect to reproduce. When found outside of host cells, viruses exist as a protein coat or capsid, sometimes enclosed within a membrane.
Philipp Velikin Reviewer. Do viruses change over time? The short answer to these questions is that viruses evolve. That is, the "gene pool" of a virus population can change over time. In some cases, the viruses in a population—such as all the flu viruses in a geographical region, or all the different HIV particles in a patient's body—may evolve by natural selection.
Read more: What came first, cells or viruses? They fail the second question for the same reason. Unlike living organisms that meet their energy needs by metabolic processes that supply energy-rich units of adenosine triphosphate ATP , the energy currency of life, viruses can survive on nothing.
In theory, a virus can drift around indefinitely until it contacts the right kind of cell for it to bind to and infect, thus creating more copies itself.
In short, yes. For one thing, some viruses do contain parts of the molecular machinery required to replicate themselves. The gigantic mimivirus — an example so large that it was initially mistaken for a bacterium, and has a genome larger than that of some bacteria — carries genes that enable the production of amino acids and other proteins that are required for translation, the process that for viruses turns genetic code into new viruses.
Mimivirus still lacks ribosomal DNA, which codes for the assembly of proteins that carries out the translation process. Read more: What happens in a virology lab? Another sign of the fuzzy boundaries between living and non-living is that viruses share a lot of their genetics with their host cells.
A study of protein folds, structures that change little during evolution, in thousands of organisms and viruses, found folds shared across all and only 66 that were specific to viruses. Their demotion to inert chemicals came after , when Wendell M. Stanley and his colleagues, at what is now the Rockefeller University in New York City, crystallized a virus— tobacco mosaic virus—for the fi rst time.
They saw that it consisted of a package of complex biochemicals. But it lacked essential systems necessary for metabolic functions, the biochemical activity of life. Stanley shared the Nobel Prize— in chemistry, not in physiology or medicine—for this work. Further research by Stanley and others established that a virus consists of nucleic acids DNA or RNA enclosed in a protein coat that may also shelter viral proteins involved in infection. By that description, a virus seems more like a chemistry set than an organism.
But when a virus enters a cell called a host after infection , it is far from inactive. These behaviors are what led many to think of viruses as existing at the border between chemistry and life. More poetically, virologists Marc H. Molecular biologists went on to crystallize most of the essential components of cells and are today accustomed to thinking about cellular constituents—for example, ribosomes, mitochondria, membranes, DNA and proteins—as either chemical machinery or the stuff that the machinery uses or produces.
This exposure to multiple complex chemical structures that carry out the processes of life is probably a reason that most molecular biologists do not spend a lot of time puzzling over whether viruses are alive. For them, that exercise might seem equivalent to pondering whether those individual subcellular constituents are alive on their own. This myopic view allows them to see only how viruses co-opt cells or cause disease.
The more sweeping question of viral contributions to the history of life on earth, which I will address shortly, remains for the most part unanswered and even unasked. For example, a living entity is in a state bounded by birth and death. Living organisms also are thought to require a degree of biochemical autonomy, carrying on the metabolic activities that produce the molecules and energy needed to sustain the organism.
This level of autonomy is essential to most definitions. Viruses, however, parasitize essentially all biomolecular aspects of life. That is, they depend on the host cell for the raw materials and energy necessary for nucleic acid synthesis, protein synthesis, processing and transport, and all other biochemical activities that allow the virus to multiply and spread. One might then conclude that even though these processes come under viral direction, viruses are simply nonliving parasites of living metabolic systems.
But a spectrum may exist between what is certainly alive and what is not. A rock is not alive. A metabolically active sack, devoid of genetic material and the potential for propagation, is also not alive. A bacterium, though, is alive. Although it is a single cell, it can generate energy and the molecules needed to sustain itself, and it can reproduce.
But what about a seed? A seed might not be considered alive. Yet it has a potential for life, and it may be destroyed. In this regard, viruses resemble seeds more than they do live cells. They have a certain potential, which can be snuffed out, but they do not attain the more autonomous state of life. Another way to think about life is as an emergent property of a collection of certain nonliving things.
Both life and consciousness are examples of emergent complex systems. They each require a critical level of complexity or interaction to achieve their respective states.
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