16 ms·
Fascinating research into the question of how the first eukaryotic cells arose from prokaryote antecedents. The ancestors of the mitochondria organelles you se
by wombatmobile 5y ago
Fascinating research into the question of how the first eukaryotic cells arose from prokaryote antecedents.
The ancestors of the mitochondria organelles you see today in every cell in your body were once free swimming bacteria, in a world where there were no animals, and no eukaryotic cells. Planet earth then, and for its first 2 billion years, was populated exclusively by bacteria, or single celled organisms. These cells were about one hundredth the size of the cells in your body.
How did life on earth become more complex?
Billions of years before the Cambrian explosion, when the number of animal species exploded into the millions, something much more basic happened at the cellular level. Cells became more complex.
How?
Maybe cells engulfed other cells, and the engulfed cells survived, forming a partnership or a colony.
Or maybe different types of cells hung out in close proximity, in colonies, which eventually merged into a network of DNA exchanging nodes that keep growing in complexity and interdependency.
We don't know.
This new effort to grow and study archea in vitro gives us something to study and experiment with.
- estaseuropano 5y agoI very warmly recommend the book "Sex, power, suicide" which explores different theories on how we came to have mitochondria and their impact and role. Dense reading but I learned something on every single page. The author more or less concludes (highlighting also limitations of the science and current knowledge) that our cells were arachea which absorbed a methanophile bacterium that became both our today's mitochondria and a parallel process for the chloroplasts in plants (with possibly a common ancestor if I remember well).
- blacksmith_tb 5y agoChloroplasts are also thought to have been engulfed and recruited to stay on as organelles[1], mind-boggling stuff. 1: https://en.wikipedia.org/wiki/Chloroplast#Lineages_and_evolution https://en.wikipedia.org/wiki/Chloroplast#Lineages_and_evolu...
- wombatmobile 5y agoThis made perfect sense to Lyn Margulis, an evolutionary biologist who was once married to astronomer Carl Sagan. She put up with decades of skepticism and derision from older scientists before Woese and Doolittle identified the genetic data in chloroplasts that confirmed the theory. The History of Evolutionary Thought → 1900 to present → Endosymbiosis: Lynn Margulis https://evolution.berkeley.edu/the-history-of-evolutionary-thought/1900-to-present/endosymbiosis-lynn-margulis/ https://evolution.berkeley.edu/the-history-of-evolutionary-t... Lynn Margulis and the endosymbiont hypothesis: 50 years later https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426843/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5426843/
- estaseuropano 5y agoAlready said in another comment, but I recommend the book "Sex, power, suicide" which explores the history of mitochondria and their evolutionary and todays role. The author also discusses Lyn's theories and partially absolves her (in particular on the symbiosis) but also highlights where her further theories don't hold up.
- emmelaich 5y ago> mitochondria organelles ... were once free swimming bacteria Maybe same goes for cilia, centrioles, golgi body, nerve cells ..
- estaseuropano 5y agoNo, these are cell organs that also exist in simpler lifeforms, and they don't hold DNA. Key is that mitochondria have their own DNA and multiply independently of the host cell.
- wefarrell 5y ago"Planet earth then, and for its first 2 billion years, was populated exclusively by bacteria, or single celled organisms" Bacteria are just one of the types of single celled organisms that populated the earth before multicellular organisms emerged.