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DNA replication seems so mechanical- the DNA polymerase just running along the template strand. I just don't understand how mutations can arise. When it comes to substitutions, I get that a wrong nucleotide may just bind and it won't be as strong a binding as with the complementary base, but I suppose it can happen. However when it comes to mutations such as insertions or deletions, I dont understand how the DNA polymerase could just skip a section of the DNA or add in extra bases. Chromosome translocation also seems like a mystery to me- almost as if the cell believes it should undergo meiosis but with the wrong chromosomes paired up and it only occurs with one pair...

I realise that this is quite a broad question, but any information on the mechanism of how mutations occur would be much appreciated :)

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  • $\begingroup$ There are various mechanisms. If you just want to know the ways by which mutations occur then this question is not broad. However, if you want each of the mechanisms explained to the molecular level then the question is definitely broad. I suggest that you focus your question on replication errors and remove other stuff. Add more background for this specific area if possible. $\endgroup$
    – WYSIWYG
    Nov 24, 2015 at 9:00
  • $\begingroup$ I think the DNA polymerase itself is not completely perfect as you'd presume in theory, it does make mistakes which result in mutation. $\endgroup$
    – Technetium
    Nov 25, 2015 at 2:46

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Mutation of DNA can be caused by an exogenous or endogenous source. Many external factors like irradiation or chemicals induce mutations. Some endogenous mutations arise from oxidative stress, insufficient DNA repair or spontaneous mutations on the molecular level.

There are many mechanisms for DNA repair like base excision repair, nucleotide excision repair, homologous end-joining or nonhomologous end-joining (Löffler, Biochemistry and Pathobiochemistry). But it is more difficult for the cell to repair the mutation if it is present in both DNA strands. According to your second question:

DNA polymerase could just skip a section of the DNA or add in extra bases

DNA polymerase cannot reconstruct what was the original strand or the orientation of the strand. To prevent cell death, some DNA repair mechanisms include alteration in the genome. The DNA polymerase can reads through and the mutation will be replicated when the cell divides. Consequently, the key question is how the effects of the mutation influence the ability of the cell to survive.

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    $\begingroup$ It will be nice if you add few references. $\endgroup$
    – Dexter
    Dec 9, 2015 at 11:54

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