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mdielmann t1_jbq3wst wrote

By these definitions for eat and grow, a fire is alive. I'd consider prions no more alive than fire, while still being as dangerous as fire.


dave-the-scientist t1_jbq760p wrote

Behold, a man!

But yes, examples like fire (nice idea on that one btw) are why "life" is weirdly tricky to define.


mdielmann t1_jbq8clj wrote

I get the edges are very blurry when defining what something is or isn't in biology, but I wouldn't equate destroy or alter with consume, or grow with reproduce, either.


dave-the-scientist t1_jbqteik wrote

When you hear "consume" or "metabolize", it doesn't just mean destroying or altering a molecule. The important bit is that energy is removed from the molecule and used by the "organism" in question. Fire definitely does count for that particular one, as the reaction to burn something is almost exactly what we do in our bodies. We burn our food, just much more slowly. A prion though, does not meet that criteria. It does alter a molecule (the non-dangerous form of the prion protein), and energy is removed (the dangerous form of the prion is at a slightly lower energy level, I believe), but the original prion doesn't do anything with that energy. It is unchanged.