I don’t understand the headline (yes I skimmed the article). Why would mitochondria not be alive? What does that even mean?
mitochondria were thought to just be a component of the cell. But they have their own DNA separate from that in the cell's nucleus. They replicate on their own like bacteria.
... hundreds of years ago, for a short time after they were discovered.
We know that they behave like bacteria for almost as long as we know that they exist.
That's a discussion about word semantics that has no relation to biology. Biologists have been occupied with it for centuries, just like computer people have lost time on "what's intelligence?", but neither one is relevant for either field.
> Are they bacteria?
Once upon a time, their ancestors were. I do not know exactly where biologists trace the line, but this is also about word semantics. It's just a case of it that helps people communicate better, so there is a line, I just don't know what it is.
If a mitochondria is not "alive," then is it dead? Even if it is taking part in an active, living cell?
Mitochondria have for many generations now been known to have their own DNA and replicate on their own. So I’m not sure what new distinction is being drawn?
So, the modification would be that we are living in symbiosis with mitochondrial bacteria, similar to how we live in symbiosis with our gut bacteria, rather than them being classified as "organelles" of eukaryote cells.
> A mitochondrion (pl. mitochondria) is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi.
and the "classification" is introduced with
> There are two hypotheses about the origin of mitochondria: endosymbiotic and autogenous.
But if you wanted classify them based on functionality rather than evolutionary history, I'd say they're more like viruses. They have only a handful of genes themselves, and exploits the nucleus' genetic material for all the other proteins it needs to function.
General acceptance of the endosymbiont theory is a relatively recent (much less than 50 years) phenomenon.
But I have never been a fan of that argument either, both seem alive to me.
It's a bit like if you took the heart from an animal and transplanted it into a human: is it meaningful to call it independently alive? Maybe, it depends what question you're trying to ask.
The uncertainty, I understood, was whether to classify them as distinct organisms the way we classify other species, as they are intrinsically parasitic for their replicative capability.
In fact the only place they fit the definition is reproduction, and that is only through the machinery they commandeer from the cells they infect.
To me viruses clearly do not fit the definition of life. But fire... that is hard to exclude from the definition without some mental contortions. I am not advocating that fire is alive for any useful reason, but it is hard to exclude from the definition.