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Doesn't DNA have a halflife of like 512 years? I imagine if every cell in the body affected by that there isn't a way to prevent it all from destabilizing by th
by Madmallard 5y ago
Doesn't DNA have a halflife of like 512 years? I imagine if every cell in the body affected by that there isn't a way to prevent it all from destabilizing by that point.
- ALittleLight 5y agoPresumably that doesn't apply if your cells are continuously reproducing creating new copies of DNA. In some sense your DNA comes from your parents and extending back through those lineages has lasted vastly longer than 512 years.
- allisdust 5y agoWow that's actually quite insightful. There are theories on cell death after some generations, dna damage etc. But I'm not sure how they explain the refresh during birth/zygote formation. Could it be that birth is nothing but a glorified error correction with two unrelated dna to ensure probability of damage is low. If so, can the same be done with two unrelated dna pairs again again and the result applied back to a living human.
- forinti 5y agoI think it was in Lynn Margulis' book What is Life that I read that sexual reproduction occurs more where there are more parasites, which gives strength to the idea that sex is error correction.
- ALittleLight 5y agoThere are clonal trees that have lived much longer than 512 years too with the same DNA. https://en.wikipedia.org/wiki/List_of_oldest_trees https://en.wikipedia.org/wiki/List_of_oldest_trees
- allisdust 5y agoTrees in general live longer probably because of their tougher cell walls? Or may be their error correction mechanisms happen during cell division? (just guessing)
- Qem 5y ago> But I'm not sure how they explain the refresh during birth/zygote formation. Probably it's just survivorship bias. When a organism has trillions of cells, it can afford to have some fraction of them damaged. It just carries on with degraded function. When it has a single cell, all essential genes must be functional, or it dies before anyone knows there was a pregnancy. It's a bottleneck. The zygotes that made it to birth are the ones lucky enough to receive a minimally viable set of undamaged genes from both parents. Most couples try a lot before one successfull pregnancy.
- xenadu02 5y agoNo, cells have active DNA repair mechanisms working all the time. They also have transcription ECC that attempts to detect and/or correct transcription errors. Some critical protein coding sequences are arranged to make some errors harmless, or are duplicated, etc. Selection pressure plays a large part here. Waterbears (tardigrades) have exceptional DNA repair mechanisms — far superior to ours in some ways — because they must survive constant dehydration and rehydration cycles. Without the ability to repair what we would consider catastrophic DNA damage they'd have gone extinct long ago.
- BenjiWiebe 5y agoDNA is continually regenerated.
- Madmallard 5y agoDoesn't that mechanism degenerate in seemingly an innumerable number of ways