Discussion of everything related to the Theory of Evolution.
If DNA didn't mutate then there would be nothing for natural selection to work on - so no evolution and no ability to adapt to change.
So some level of mutation is essential. Does anybody know if there is any evidence to suggest that there are biochemical systems to promote mutation (at some low level) or does it rely on environmental effects to generate enough mutation? It seems to me that there must be some balance, the right amount of mutation and I'm curious about how cells manage this...
This is a very good question. Certainly life would have remained at a very "primitive" level without the ability of genetic material to mutate. The balance is primarily mantained by the accuracy of polymerases that copy DNA and by the efficiency of error correcting mechanisms. The environment also plays a role in creating errors in non-replicating DNA that can be copied later, though this is pretty much a non-changing parameter.
Many viruses, for example use very sloppy polymerases, which allows them to mutate much faster than organisms. This is a factor that makes it hard to keep up with vaccines (such as those for influenza).
Last edited by robsabba on Wed Oct 07, 2009 3:45 pm, edited 1 time in total.
you have said yourself that natural selection works with the mutated DNA
but NS t does not and cant generate that mutated DNA
what ever caused the DNA to mutate might be responsiblie for the generation of new species
but NS is not responible for the generation of new species- ie new genes
Please just ignore gamila. He is a troll-bot.
To get to the original question, DNA mutates because huge molecules have a decent level of instability. What you will find, however, is that organisms which are well-adapted to very stable parts of the environment (like pelagic sharks or horseshoe crabs) tend to have much better mutation-repair chemistry. For them, mutational variation is non-adaptive.
That makes sense. So in a stable environment mutation rates will tend to be lower than in changing environments (because changed DNA is more likely to be repaired). Is their any evidence that mutation rates (after any repairs) increase if organisms are subjected to environental stress?
well I don't think DNA repair is ever 100% effective (except for maybe DSB repair which is close to that). Repair pathways miss some stuff, so if you got 100 times as many mutations as normal, it is conceivable that after repairs you are still left with something like 2-3% more mutations as normal, which in turn could increase adaptation
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter
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