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I love the RNA world hypothesis, I love the idea that DNA is an iteration on RNA optimised for stable data storage, that proteins are and iteration on RNA optim
by monkeycantype 4y ago
I love the RNA world hypothesis, I love the idea that DNA is an iteration on RNA optimised for stable data storage, that proteins are and iteration on RNA optimised to be better enzymes and structures and that mediating between the two we still have to transcribe data to the legacy RNA data format, and use the legacy RNA enzyme ribosomes to translate this through to amino acid sequences.
The idea the RNA metabolisms might have evolved in small cavities in hydrothermal vents also makes it easy to imagine communities of cooperating molecules in an enclosed area needing to defend themselves from free-loading virus molecules, setting up the ongoing conflict between cells and viruses right from the beginning, and also a dynamic in which viruses are both destructive and an important source of novelty
- ncmncm 4y agoImagine the seas a thick soup of iron complexes and RNA folded into quadrillions of nightmare shapes, a vanishing few of them busy replicating whatever they bumped into. One day, two of them bumped into one another. In the blink of a geologic eye, the seas were brimming with a descendant of whichever of them was faster. Somewhere, a membrane happened. I don't think anywhere in nature today do we find a membrane created entirely from scratch. Everywhere we find a membrane, it grew from and split off of an existing membrane. It may be that we should think of ourselves as fancy membranes, and DNA, RNA, and protein are just clever ways to make more membrane.
- convolvatron 4y agomy hazy memory is that it is/was assumed that the cell wall arose pretty naturally from an asymmetric protein that was hydrophilic on one end and hydrophobic on the other.
- monkeycantype 4y agoThe hydrothermal vent as a spongey matrix of cell membrane precursors is one theory for this. The thing I like about this idea is that the idea of a boundary exists before membranes, and fit with the idea of the boundary being ‘found’
- meetups323 4y agoBubbles would like to interject. as found in sea foam, for instance.
- ncmncm 4y agoSea foam bubbles, really? Trolling is frowned upon here.
- meetups323 4y agoWhat is it about free lipids and proteins spontaneously joining together in chaotic aquatic environments to form highly resilient microscopically sub-dividable shells that you find so trollishly unrelated to the concept of membranes forming in early earth conditions?
- kadoban 4y agoThis would have been at a period before any real sophisticated attackers exist, and before life had built up any specific requirements of an "internal" environment too. It seems intuitive that this would be how it started, goopy little bubbles filled with goo, just barely keeping out the other goo that would disrupt it.
- ncmncm 4y agoWhen you find a living organism relying on sea foam to construct an organelle, you may file for your Nobel Prize. Literally all the organisms we know about make all the membranes they use by adding to an existing membrane, not fetching them from out of their environment. And really, why should they? Finally: a soap bubble film has air on both sides, and water solution between, and is thus the opposite of any membrane in a cell, which has water on both sides and glyceride in between.
- kadoban 4y agoIt had to start somewhere, and expecting it to have started with what is currently done sounds optimistic.
- achillesheels 4y agoI love the idea that this can be modeled using Signals and Systems Theory, e.g. Fourier Analysis of the digital signaling of protein sequencing
- monkeycantype 4y agoI'd like to read more about what you're thinking here.
- kvetching 4y agoRelated to this; Check out the book The Revolutionary Phenotype. "The Revolutionary Phenotype is a science book that brings us four billion years into the past, when the first living molecules showed up on Planet Earth. Unlike what was previously thought, we learn that DNA-based life did not emerge from random events in a primordial soup. Indeed, the first molecules of DNA were fabricated by a previous life form. By describing the fascinating events referred to as Phenotypic Revolutions, this book provides a dire warning to humanity: if humans continue to play with their own genes, we will be the next life form to fall to our own creation. "I am VERY impressed with this book—very important topic very well treated." - Robert Trivers" https://www.goodreads.com/en/book/show/43128410-the-revolutionary-phenotype https://www.goodreads.com/en/book/show/43128410-the-revoluti... The book defines the transition from RNA to DNA as a Phenotypic Revolution
- CodeAndCuffs 4y agoI'm skeptical of genetic theories constructed solely by a white supremacist [1]. A stopped clock is still right twice a day, but there's kind of a pattern of men who say "white people are superior and Jews are bad" also proposing other unfounded ideas in the name of "science". Also he tried to get Jeffrey Epstein to fund this book. Neat. [1]https://en.m.wikipedia.org/wiki/Jean-Fran%C3%A7ois_Gari%C3%A9py https://en.m.wikipedia.org/wiki/Jean-Fran%C3%A7ois_Gari%C3%A...
- pfdietz 4y agoI dislike the RNA world hypothesis, since actual RNA nucleotides will be vanishingly rare in the soup, vs. other random similar organic molecules. Cells have these monomers because of synthetic chains with enzymes that precisely catalyze the various steps to get to them.