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joozwa t1_irmlex1 wrote

Reply to comment by Shadpool in What lifeform has the shortest genetic sequence? by teafuck

Virus is a handful of molecules that in a certain environment tend to react physico-chemically as the chemical structure and properties of molecules dictate. If you deem it as an "active and deliberate" you'd have to consider every chemical reaction as active and deliberate. By this definition, a catalytic converter in your car is alive.

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AedemHonoris t1_irnay9e wrote

I think the biggest thing is viruses don't react to their environment in how prokaryotes and eukaryotes do. The latter can change gene expression to interact with their environment and even move deliberately (bacteria moving towards chemical signals and then changing membrane proteins to interact with their environment). Viruses just float around, like how atoms flow with little direction and can interact with what's around them the same as 2 hydrogen molecules can interact with an oxygen molecule.

I don't consider viruses or prions alive anymore than I do proteins or atoms.

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joozwa t1_irnisdx wrote

Indeed, there's much more going on in biological systems than just merely a replication. There's both anabolic and catabolic reactions, and compartmentalization allowing for these reactions in the first place. There are different receptors acting as an input signals that influence the aforementioned reactions. Viruses lack all of that, including arguably even replication, which they can't do by their own. There's not even any spectrum here - viruses don't have any biochemistry, and even the simplest bacteria or archea exhibit all of the processes mentioned.

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