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Viruses are among the biggest threats to humanity, with the current pandemic showing how these pathogens can shut down countries, halt entire industries and cause untold human suffering as they ...
Whether or not viruses should be considered as alive is controversial. [ 35 ] [ 36 ] They are most often considered as just gene coding replicators rather than forms of life. [ 37 ] They have been described as "organisms at the edge of life" [ 38 ] because they possess genes , evolve by natural selection, [ 39 ] [ 40 ] and replicate by making ...
How viruses do this depends mainly on the type of nucleic acid DNA or RNA they contain, which is either one or the other but never both. Viruses cannot function or reproduce outside a cell, and are totally dependent on a host cell to survive. Most viruses are species specific, and related viruses typically only infect a narrow range of plants ...
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. [1] Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. [2] [3] Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.
Unlike viruses, they are living organisms that can live and reproduce on their own. The vast majority of bacteria don’t hurt us, and many – like the ones that live in our gut and help digest ...
Thus, an argument that viruses should be classed as living organisms is their ability to undergo evolution and replicate through self-assembly. However, some scientists argue that viruses neither evolve nor self-reproduce. Instead, viruses are evolved by their host cells, meaning that there was co-evolution of viruses and host cells.
A virus with this "viral envelope" uses it—along with specific receptors—to enter a new host cell. Viruses vary in shape from the simple helical and icosahedral to more complex structures. Viruses range in size from 20 to 300 nanometres; it would take 33,000 to 500,000 of them, side by side, to stretch to 1 centimetre (0.4 in).
Respiratory viruses are continuing to spread across the United States, sickening millions of Americans. Overall respiratory illness activity -- including flu, COVID-19 and RSV -- continues to be ...