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Mitochondria and the origin of eukaryotes

knowablemagazine.org

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Re: Mitochondria and the origin of eukaryotes

#71

Post by Ericson2314 »

pmags wrote: post #20

For those interested but new to role of endosymbiosis in evolution, it's useful to keep in mind that there's strong evidence of an endosymbiotic origin of chloroplasts, another major event in the history of life. Here's a recent review article that highlights some of the key evidence and outstanding questions: Sibbald SJ, Archibald JM. Genomic Insights into Plastid Evolution. Genome Biol Evol. 2020 Jul 1;12(7):978-99…

Isn't that long established, as the article says?

The article, and yours too I would assume, mentions https://en.m.wikipedia.org/wiki/Paulinella which is really cool for being a second known primary symbiosis.

Greatest rerun of all time!

Re: Mitochondria and the origin of eukaryotes

#72

Post by Ericson2314 »

photochemsyn wrote: post #16
alangibson wrote: post #2

> For billions of years after the origin of life, the only living things on Earth were tiny, primitive cells resembling today’s bacteria I've often used this "fact" as an argument against complex extraterrestrial life. Glad to see it might be wrong after all.

The rise of free atmospheric oxygen and oceanic dissolved oxygen levels were almost certainly a requirement for the development of complex multicellular life. Using oxygen as the electron acceptor in respiration means far more energy can be extracted from reduced fuel molecules (sugars, fats, amino acids, methane, hydrocarbons, ammonia, etc.) than by using species like oxidized sulfur and iron, CO2, or nitrate (NO3)…

To your last parenthetical, organicism a la Hegel mends the blind spots once again!

Re: Mitochondria and the origin of eukaryotes

#73

Post by gus_massa »

simonh wrote: post #61
gus_massa wrote: post #53

Earlier quoted context omitted.

Multicellularity looks relatively easy. From https://en.wikipedia.org/wiki/Multicellular_organism#Occurre... > Multicellularity has evolved independently at least 25 times in eukaryotes, and also in some prokaryotes, like cyanobacteria, myxobacteria, actinomycetes, Magnetoglobus multicellularis or Methanosarcina. However, complex multicellular organisms evolved only in six eukaryotic groups: animals, symbiomycotan fu…

It’s relatively easy once you have evolved the biochemical infrastructure to support it, but on Earth that took several billions of years to achieve. There’s no way around it, no amount of hand waving how easy it is negates the fact it took billion years of evolution to do it. Also most of those forms of multicellularity are extremely basic, little more than tangles or sheets of cells, even after hundreds of millions…

I think we agree. One you have prokaryote it's probably easy to get multi cellular prokaryotes.

My guess is that the transition form eukaryotes to prokaryotes in the hard step.

Also, photosynthesis seams to be more complicated than what I expected. Perhaps that is the hardest step. (It's an indirect step to intelligent life, but perhaps a lot of free oxygen to burn food efficiently is necessary for intelligent life.)

Re: Mitochondria and the origin of eukaryotes

#74

Post by bergenty »

anton96 wrote: post #19
frostburg wrote: post #8

Earlier quoted context omitted.

Presumably like we do - (I'm heavily simplifying the complex regulation involved) the mitochondria have their own DNA which gets duplicated when the cell prepares to undergo mitosis, then the two new cells split the results.

Does that implies that mitochondria also had to evolve at some point to detect duplication of their host cell so they duplicate at the same time?

I know the cytoplasm between cells is split on division and corresponding the mitochondria are roughly as well. They could technically have different times of reproduction than the overall cell and it would still work. I’m not certain what actually happens to the mitochondria during cell division though.

Re: Mitochondria and the origin of eukaryotes

#75

Post by gus_massa »

ncmncm wrote: post #10

If they find cells lacking some organelle, it will be hard to say whether it was never acquired, or was later abandoned. One clue would be leftover genes from when it was there. Eukaryotes often find it hard to prune out excess DNA, vs. just turning it off.

For example the ancestor of Trypanosoma had chloroplast https://en.wikipedia.org/wiki/Trypanosoma#Evolution https://en.wikipedia.org/wiki/Euglenozoa#Structure

Re: Mitochondria and the origin of eukaryotes

#77

Post by mgraczyk »

Surprised the article doesn't mention Viral Eukaryogenesis, the hypothesis that the nucleus of Eukaryotes evolved from a virus.

https://en.wikipedia.org/wiki/Viral_eukaryogenesis

My understanding is that there is much less evidence for this, but it seems like the question of whether or not there were multiple gradual endosymbiotic events in eukaryotic evolution would definitely depend in some way on viruses.

Re: Mitochondria and the origin of eukaryotes

#78

Post by BrainsPachanga »

code_biologist wrote: post #62
aesch wrote: post #57

Earlier quoted context omitted.

I haven't read that one but after reading The Vital Question I will recommend anything with Nick Lane's name on it. There are very few people who have thought about the origin of life as deeply as he has.

Read it as soon as you have the time. It is every bit the equal of The Vital Question.

Does this book address how potentially the first cell ever came to exist? If not, do you have any suggestions?

Re: Mitochondria and the origin of eukaryotes

#79

Post by ssl232 »

aesch wrote: post #58
ssl232 wrote: post #26

Earlier quoted context omitted.

Nick Lane's book The Vital Question is a masterpiece. I reckon he's figured out the origin of life there. I hope he gets on some podcast like Lex Fridman to talk about it all, because his ideas are just waiting to explode into the public imagination.

He was just on Sean Carroll's podcast Mindscape, good listen: https://www.youtube.com/watch?v=9IZ_CVu2M68

Awesome! Thanks for the link, I'll give this a watch!

Re: Mitochondria and the origin of eukaryotes

#80

Post by simonh »

sterlind wrote: post #65
simonh wrote: post #61

Earlier quoted context omitted.

It’s relatively easy once you have evolved the biochemical infrastructure to support it, but on Earth that took several billions of years to achieve. There’s no way around it, no amount of hand waving how easy it is negates the fact it took billion years of evolution to do it. Also most of those forms of multicellularity are extremely basic, little more than tangles or sheets of cells, even after hundreds of millions…

it took at most a billion years. there may have been predecessors that were lost - the only evidence we have from that era is what made it into the DNA of surviving ancestors. I guess I still feel like abiogenesis should be the bigger filter. we have ideas and suggestive experiments about how it happened, but nothing's come close to convincingly demonstrating how fully self-replicating life can evolve through simple…

As I pointed out though, endosymbiosis isn’t by itself enough. It can provide many benefits, one of which might be the ability to develop complex sophisticated multicellular organisms, but it doesn’t guarantee that capability.

This sub thread is specifically about developing intelligent life, and of all the branches of multicellular life on earth only one has achieved that capacity, animals. None of the others seem to be anywhere close, or ever likely to be, for all their fancy biochemical tricks. So it seems like the vast majority of endosymbiotic events really don’t help much towards that outcome.

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