Why could prokaryotes survive without eukaryotes but eukaryotes could not survive without prokaryotes?

Answer 1

Stanton's answer is a good one, so I'm not going to repeat it here (read it, upvote it, etc.) But there is something I would like to add, namely, where to mitochondria come from?

Now, eukaryotes are highly reliant on mitochondria in order to metabolize food. But a curious thing about mitochondria is that they have their own DNA, independent of the nucleus and in fact, not derived from the nucleus. Why's that? The current theory is that mitochondria were once separate prokaryotic organisms that were engulfed by early eukaryotic cells. The eukaryotic cell that entered into a symbiotic relationship with those engulfed mitochondria had a huge evolutionary advantage: now they could make a lot more energy. And from the perspective of the mitochondrion, if you have a cell that's protecting and feeding you, well, that's pretty cool, so you're happy with the arrangement.

In short, every eukaryotic cell pretty much contains what used to be prokaryotic cells inside of it.

Answer 2

Hi Cesar L.,

If you are a prokaryote, where do you obtain the energy you require to live? You photosynthesize it, or use other respiration mechanisms. You might also parasitise eukaryotes, but between eukaryotes (so to speak) you have to go it on your own. Or you could attack other prokaryotes. So you don't NEED the eukaryotes, in order to survive.

But a eukaryote, now -- you might photosynthesize, but the overwhelming odds are that you require some assistance (commensal mycorrhizae, for example, in >~90% of plant families); as a mammal, you know you NEED those commensals in your gut. But more fundamentally, what group of organisms are decomposers, so that you have access to any nutrients whatsoever? And what group of organisms fix nitrogen, so that it becomes available for the nitrogen cycle?

-- Cheers, Mr. d.