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To my (limited) understanding, there are 2 main ways that mutations can occur in DNA: Environmental (UV, etc) and mistakes during cell division.

I was wondering if there is a mechanism that can give priority to certain genes to be accurately duplicated. Some sort of trigger that says "double-check this specific gene before continuing with the duplication".

And if there is such a mechanism, then I wonder if there is some sort of dependency system for genes that control groups of other genes. So that if a certain gene "activates" the double-check trigger, it would automatically add that trigger to the group of genes which are affected by it.

Thanks.

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  • $\begingroup$ All DNA is proofread during replication. It is also constantly monitored for damage. $\endgroup$ – canadianer Jun 11 '15 at 16:58
  • $\begingroup$ are all regions have same mutation rate? bonus points: independent of sequence (only location). E.i., are there markers of super-stable sequences $\endgroup$ – aaaaa says reinstate Monica Jun 11 '15 at 17:16
  • $\begingroup$ Can you add some details. Your exact question remains unclear to me. Gene duplication is not essentially a regulated process. $\endgroup$ – WYSIWYG Jun 11 '15 at 17:21
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    $\begingroup$ No such mechanisms as far as I know. Some DNA regions are harder to repair, notably repeated sequences but I am not aware of any mechanism giving a specific higher priority for repair to any genes. Also I think you want to use the term "replicated" and not "duplicated". @aandreev while interesting, mutation rates seem irrelevant for this question. $\endgroup$ – cagliari2005 Jun 11 '15 at 18:14
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So far, the known mechanism of DNA repair is to recognize mismatches or damaged nucleotides by enzymes surrounding DNA rather than by scanning along DNA. Therefore double check could not happen under such conditions.

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DNA mutations arise from either replication errors or the effect of mutagens. Cell division can go into what is known as the G0 phase where division is put on hold. This state is also referred to as a quiescent state (see the related genes here), which is distinct from senescent states where damaged cells are prevented from replicating by, for example, the p53 gene family. The proteins of these last mentioned genes are up-regulated to suppress uncontrolled division in cancerous cells, while genes controlling the G0 phase act under normal physiological conditions, unless these related genes are deficient themselves. Carcinogens are a subset of mutagens that typically affect genes involved in the cell cycle.

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I was wondering if there is a mechanism that can give priority to certain genes to be accurately duplicated. Some sort of trigger that says "double-check this specific gene before continuing with the duplication".

A mechanism that would say: "double check this part, it's important" isn't known to me neither, but if I understood your question correctly I think the answer to your question lies somewhere else.

Let's start with the mutation rate you mentioned, some sequences are harder to replicate by DNA polymerase (it makes more mistakes there, such as in highly repetitive sequences, methylated cytosines etc.), so the mutation rate is higher in these segments (they are called mutation hot spots), but otherwise the DNA polymerase makes errors randomly, throughout the whole genome. These are in better case repaired. No special care given, repair polymerase tries to repair everything.

Now, to my point. What if the repair fails? In genes, that are critical to cell survival, development of organisms etc. (for it's life) you really see less mutations (if any) present. (and I believe this was the reason for the question, correct me if I am wrong.)

Moreover, these places in genome can be highly conserved between different organisms. More here. What this says is that nature doesn't allow cells/evolution/whoever to experiment (or make errors) on these positions. If mutation occurs here and isn't repaired, the cell simply dies and therefore you cannot see the mutation. The reason for death may be accumulation of toxic protein, which cell is not able to get rid of with disrupted enzyme, or lack of energy, because it cannot oxidize fuel... there are plenty possible lethal outcomes. For some genes, the cell can substitute their product by another protein, but some are essential.

(In multicellular organism can substitute for it, unicellular won't care because it's dead already)

I believe this is the mechanism, by which cell can distinguish between important and "less important" genes you were asking for.

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