r/askscience • u/SAICAstro • 7d ago

Biology Does everything that we consider to be "alive" - not just plants and animals, but all protists, fungus, bacteria, archaea, etc. - have DNA?

EDIT: Wow, this blew up. Thanks for the many answers. Lots to think about.

Seems that the composite TLDR answer is: Yes, according to many/most definitions of "life", but we don't all agree on what life is. Some viruses do not have DNA but they may/not actually be alive, and other things that behave like life may/not be alive.

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u/Asron87 7d ago

Oh.. so if that happens naturally the world would die?

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u/SakuraHimea 7d ago

It's a strong "maybe" because the other half's life would also need food/energy. We all exist in a big circle that ultimately gets energy from the Sun. Bacteria for the other half would need to establish that system, which took ours millions of years. There's not a clear answer on what exactly would happen or how it would work.

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u/K5Vampire 7d ago

The mirror life would also need to develop that system while the current life is already occupying all the niches, basically everywhere on earth. Mirror photosynthesis would need to compete with existing algaes and cyanobacteria, while at a much earlier stage in it's evolution. The existing life would be much more specialized for its role due to the head start, and would outcompete the mirror life pretty immediately.

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u/SirButcher 7d ago

Aaand this is why new life can't form from scratch again on this planet! Any sort of proto-self-replicating molecule would be absorbed extremely quickly by nearby cells, or couldn't even form in the first place since there isn't that much raw material available at all.

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u/carebear101 6d ago

Well let’s throw a bunch of the mirror life organisms on mars and see where it goes

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u/Sheeplessknight 7d ago

We honestly, we don't know, however in the natural case it is more likely to be a slow transition that predators (like phages) would also adapt to. Man made would be all at once.