By one estimate, at least 320,000 different viruses can infect mammals alone, and even this massive number may be on the low side. Using that strategy, the minute marauders have flourished and evolved in step with their hosts. To identify the correct host, viruses have evolved receptors on their surfaces that match up with those of their ideal target cell, letting the virus get its genetic material inside and hijack its host's cellular machinery to help it reproduce by multiplying the virus' genetic material and proteins. But when it finds a host, a virus can multiply and spread rapidly. How do viruses multiply?ĭue to their simple structure, viruses cannot move or even reproduce without the help of an unwitting host cell.
#Do viruses carry out all life processes full#
These mega-viruses are hundreds of times larger than most, with capsids that span roughly 400 to 500 nanometers across and full viral forms that can measure up to 750 nanometers across. The one exception, a group known as giant viruses, has members with astonishingly large genomes. Such a tiny size means that you can't even spot most viruses with a light microscope. This makes them smaller than most bacteria, which can be a small as roughly a tenth the size of a human blood cell. These tiny virus packages are just tens to a few hundreds of nanometers across. Some are additionally enveloped in a soft, lipid wrapping. Each one consists of genetic material-either DNA or RNA-encapsulated in a protein pocket called a capsid. While these microbes have a dizzying array of functions and health effects, the structure of a virus is surprisingly simple. They've flourished and diversified for billions of years and perhaps even had a hand-or a squishy protein coating-in helping the first complex cellular life come to be. The tiny tagalongs aren't exactly alive by most definitions, but they're not really inanimate either.
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