Read this:
http://www.nature.co...l/041018-7.html
Hmm, I guess that's why they call it junk DNA.
But regarding concerns about other possible reasons for junk DNA -- could it be that junk DNA shields your regular DNA from mutagenic influences or damage? For instance, could junkless mice be more susceptible to damage from free radicals, UV, etc?
Would junkless mice have shorter lifespans?
This whole junk issue seems important, since you don't want to carry around more crap than you need. If you have to store junk DNA someplace, store it on your iPod. Don't carry it around with you all day in your cells, unless you really really need to.
I'd imagine that with all other things being equal, replication of junkless DNA might be more efficient and less error-prone. As a matter of fact, wouldn't gene signalling also be more efficient, since there are less spots for messenger molecules to bind to? And what about epigenetics -- wouldn't the enabling and disabling of genes be more reliable, since the methyl groups could find their way to the right spot more easily?
Intuitively, I'd imagine that junk DNA can't be all that critical, since even gene DNA gets mixed and matched all the time just because of binary sexual reproduction. And if gene DNA (introns) are getting shifted around all the time, then why wouldn't the junk DNA get even more jumbled thru binary sexual mixing?
There really should be a whole lot more testing done on the junkless mice, since junk DNA is such a large part of nucleome, even if it's not technically part of the genome. If we could significantly lighten the load and improve on what nature gave us, then it would be well worth the trouble.
We know that nature can't lighten the load itself, because nature has no alternative means of storage for the multi-generational archival information that junk DNA might contain. But we have hard drives where we can access it if we really need it. Meanwhile in our daily lives, we could live much more easily with the lighter load.
For instance, what if you replaced worthless junk DNA with backup genes? The backup genes would only kick in if your regular active genes get damaged and disabled. That could concievably lengthen our lifespans by making us more tolerant of damage to our DNA. We could be racking up the damage to our active genes, and then still have plenty of backup genes to take over and keep things running smoothly. The trick would be to only have the backup gene trigger when it's needed, when your regular genes conk out. So you need some kind of switch that gets triggered based on the expression of the main gene.
Or on the other hand, instead of having a single main gene expressing at a given rate, you could have 5 copies of that gene each expressing at 1/5 the rate. If one or two conk off due to damage, then the others will still be there to maintain some expression, rather than losing all expression altogether. And perhaps this would be less problematic/complex than the backup trigger idea.
What do you think? Comments?
And what about mitochondrial DNA specifically? Does it have any junk DNA to get rid of?
