Some of these giant so-called mimiviruses contain genes involved in metabolism and making proteins, and their genomes are even bigger than those of some bacteria – so does this indicate that viruses are living after all?Ī key to determining viruses’ elusive nature lies in how they came to exist.
However there is also a case to be made for viruses being alive.įor example, the discovery of giant viruses possessing hundreds of genes (the Ebola virus only has seven) suggests viruses are more than just simple, inert bundles of genetic material. This complete reliability on a host for all their vital processes has led some scientists to deem viruses as non-living. Outside of their host some viruses can still survive, depending on environmental conditions, but their life span is considerably shorter. The only life process a virus undergoes independently is reproduction to make copies of itself, which can only happen after they have invaded the cells of another organism. They don’t carry out metabolic processes, such as making the energy molecule of life, ATP, and they don’t have cells and therefore the cellular machinery needed to make proteins by themselves. However, viruses lack the hallmarks of other living things. Some years after their discovery, scientists first raised the idea that viruses were living – albeit simple – organisms because they caused diseases like bacteria, which we know to be alive. Since viruses were first discovered in 1892 by Dmitri Ivanovsky, our ideas of what they are have shifted from poisons to biological chemicals. So are viruses ‘alive’? The answer is not as straightforward as you may think. This means no life form is safe from infection by a virus. They are made up of DNA or RNA encapsulated in a protein shell and can only survive and replicate inside a living host, which could be any organism on earth. Viruses are microscopic parasites responsible for a host of familiar – and often fatal – diseases, including the flu, Ebola, measles and HIV.
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