General > Biology

human mutation rate

<< < (2/2)

shvarz:
A mutation in a functional part of the genome (which is certainly bigger than 5%) will not necessarily affect the functionality. Chances are very high that it will remain neutral or have a very small effect (positive or negative) on fitness.

ikke:

--- Quote from: shvarz on April 01, 2011, 12:11:57 PM ---A mutation in a functional part of the genome (which is certainly bigger than 5%)

--- End quote ---
If the definition of functional gene means functional for the phenotype, the 5 % is a low estimate. (A large part of DNA are selfish genes, genes with no benefit to the organism but the genes are good in inserting copies of themselves.) Higher estimates of % lead to higher numbers of broken genes.

--- Quote from: shvarz on April 01, 2011, 12:11:57 PM ---Chances are very high that it will remain neutral or have a very small effect (positive or negative) on fitness.

--- End quote ---
Common assumption is that most mutations are detrimental.

shvarz:
It's a wrong assumption. It appeared back when the only way to see a mutation was to observe its effect on fitness (which is usually negative). It's quite fair to say that most mutations are either neutral or effectively neutral (their effect is smaller than the reciprocal of the effective population size, see Kimura et al.).

The protein-coding part of the genome is only about 1-2%. The functional part of the genome is significantly larger (probably on the order of 20-30%) and will include a whole bunch of regulatory sequences and genome-maintenance sequences, but mutations there are much more likely to be neutral than in the protein-coding part of the genome. The functionality of most of those elements just doesn't depend upon the exact sequence.

ikke:
Even at the 1% (protein) code and 100 mutations level the chances of  being hit by a mutation is 1-(1-0.01)^100=63%. For 2% and 200 the number is 98%. I still say that mutations cannot have an equal occurrence across the genome.

shvarz:
Well, they don't. There are fairly well-known biases in mutation rates, for example CpG sites are hot-spots with mutations happening about 10 times more likely there as in other places, but that's a completely different questions.

Navigation

[0] Message Index

[*] Previous page