

More than 90% of Human DNA Is Useless 'Junk,' Study Finds - chasef
http://mashable.com/2014/07/28/functional-dna-percentage/

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s_q_b
This cuts against everything I've heard about genetics and epigenetic
developments since the the complete of the HGP. It was my understanding that
we were finding that the so-called "junk" DNA actually serves a variety of
functions in regulating and controlling protein production and usage.

Wikipedia seems to agree: "The Encyclopedia of DNA Elements (ENCODE)
project[3] suggested in September 2012 that over 80% of DNA in the human
genome "serves some purpose, biochemically speaking".[4] This conclusion
however is strongly criticized by other scientists,[5][6] with a recent
article claiming that "8.2% of the human genome is likely to be functional,
while only 2.2% has maintained constraint in both human and mouse since these
species diverged".[7]"

[https://en.wikipedia.org/wiki/Noncoding_DNA](https://en.wikipedia.org/wiki/Noncoding_DNA)

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dekhn
I'm still waiting for somebody to make a minimal human genome that removes all
the Alu sequences and shows it's viable.

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s_q_b
Or really a minimal version of any genome. Build me a fruit fly with the "non-
coding" sequences removed, and show me that its phenotypically normal. The
genomes are remarkably similar, thus proving the point while not involving
potential ethical issues.

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dekhn
Note, that I don't think this would be an easy experiment. For example, if you
removed all the Alus, you would likely break something critically functional,
but not be able to conclude specifically that it was due to removing the Alu,
rather than, say, some other complicated genomic effect.

Another way to look at it: pick a model organism (maybe c elegans), run many
experiments in parallel, finding regions which can be removed and allow
viability under a wide range of inducible environments (if you remove the heat
shock proteins, but never put the worms in a hot environment, you might
conclude you increased fitness). Find the largest regions you can remove
independently, then start with pairs of regions (you can imagine that removing
region 1 and region 2 independently would have no effect, but be fatal if
combined), etc.

The resulting genomes would probably still contain regions that contained no
recognizable function, have no strong selection pressure, and yet still be
completely necessary for viability. This is just speculation on my part,
though.

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seanflyon
Over 90% of the human genome is able to mutate and still be viable. Much
better than the reasoning I was expecting (We don't know what it does
therefore it is junk), but still seems like a bit of a stretch.

