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Is DNA a radiation hardened quine? I mean, it’s basically code that makes more of itself, even in the presence of mutations.
by asimpletune 3y ago
Is DNA a radiation hardened quine? I mean, it’s basically code that makes more of itself, even in the presence of mutations.
- quickthrower2 3y agoMaybe it is the cell that is the quine?
- laci37 3y agoIt pretty much is, but it's not rad hard in the sense that you can change or delete any one letter. Well, maybe in animals and plants, since we have at least two copies of most genes.
- enkid 3y agoDNA doesn't make a copy of itself, the cell makes a copy of the DNA. DNA doesn't really do anything, it requires RNA and proteins to actually do anything.
- rebolek 3y agowell, quine program doesn't do anything by itself too, you need computer and electricity for it to work
- enkid 3y agoThere's a definitional problem here. Would a book with instructions for how to order additional copies be a quine? What's the difference? I don't know exactly.
- mtlmtlmtlmtl 3y agoI guess the right question to ask about DNA is, does it contain all the instructions required to produce a copy of the DNA itself? DNA translation involves a bunch of RNA, sure. But DNA copying is mostly done by DNA polymerases, which are typical peptide based proteins encoded in the DNA itself, right? So in a real sense, the DNA contains the blueprint for the machinery to copy the DNA itself, but not the instructions for building that machine from the blueprint, the same way a software quine doesn't necessarily include the source code for a compiler. Definitely a definitional problem, but that's my shot at resolving it a bit. Then again, DNA polymerase is not perfect, and DNA is not immune to single nucleotide changes having a real effect, so it's only a quine in the "spherical cow" way of looking at it anyway. But it's certainly the most "quinish" thing in nature that I can think of.
- enkid 3y agoI just don't think it's accurate to say DNA has instructions in the same way a computer does. It's more like a recipe for a chemical reaction. If we expand the definition of a quine away from being self reproducing code and to self reproducing chemical reaction, it seems like things like crystalization or fire could be considered a quine.
- mtlmtlmtlmtl 3y agoI actually like that. But I may have been a bit unclear about my mapping of computer and biology terminology to this question. I tend to think of a computer programs as being mathematical machines, and proteins as being molecular/chemical machines. Motor proteins "walking" along microtubules is the most vivid example of this. I'm sort of torn between both worlds here, honestly. I like both perspectives. Viruses especially have a very quinish quality to them in that they're stripped down to just enough stuff to get a host cell to make more viruses.
- enkid 3y agoI like the virus as quine analogy much better than generic DNA as a quine, personally. Seems much more meaningful.
- PartiallyTyped 3y agoThe program doesn't make a copy of itself, the runtime makes a copy of the program. Program doesn't really do anything, it requires runtime and cpu to actually do anything.
- Karellen 3y agoDNA includes instructions for how to build all the machinery needed to make a copy of itself, including the surrounding cell, and RNA, and proteins, and the organism that is capable of gathering food/fuel to obtain the all the raw materials to build everything.
- enkid 3y agoNo it doesn't, it holds a recipe for creating proteins under specific chemical and biological conditions. If you put human DNA in a chicken egg, it wouldn't hatch a human.
- Karellen 3y agoAnd if you write a quine computer program on a piece of paper, it won't create a copy of itself further down the page. Or if you put a fully-functional cell in the vacuum of space, or the heart of a star, it won't replicate either. All replicators need a suitable environment to replicate in. The fact that inhospitable/non-viable environments exist does not negate the fact that they are actually replicators.
- tedunangst 3y agoIf you build a cell from only eukaryote DNA instructions, it won't have any mitochondria and be unable to copy itself.
- Karellen 3y agoMitochondrial DNA is still DNA. Symbiotic replicators that rely on the presence of each other to reproduce (like cycles of quines?) are also still replicators.
- tedunangst 3y agoI think also the Golgi apparatus has no DNA. You can't build one if you don't have one. But apparently we're still not sure where it comes from.
- samatman 3y agoIn some cases, this is in fact a useful way to look at it. The DDC model[0] proposes that one of the drivers of evolutionary change is polyploidy, where after an organism has multiple copies of the genome, genes are free to drift into new functions. An organism with four copies of a gene instead of the usual two is more rad-hardened than the basal non-ploid organism. [0]: https://www.researchgate.net/figure/The-duplication-degeneration-complementation-DDC-model-a-A-gene-with-four-regulatory_fig1_5859230 https://www.researchgate.net/figure/The-duplication-degenera...
- mabbo 3y agoThere's a great video recently by Kurzgesagt video recently[0] on just how hard the immune system works to identify and kill any cell that is not cooperating anymore. In a nutshell, the DNA fails at protecting from changes all the time, and the immune system is constantly checking for that and killing off those cells. [0]https://youtu.be/zFhYJRqz_xk https://youtu.be/zFhYJRqz_xk
- _yb2s 3y agoIt's not robust to any point mutation, only some, but I would still say this is a fair point