Friday, 13 November 2015

Jumping Genes Jump All Over Creationism


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Grabbing a parasite by the tail: Team solves 'jumping gene' mystery: First demonstration of the poly(A) tail's key role in LINE-1 retrotransposition -- ScienceDaily

Here's a conundrum for creationists.

What intelligent purpose could there possibly be for creating short pieces of DNA that randomly cause genetic diseases such as haemophilia, Duchenne muscular dystrophy, and cancer by randomly jumping from one location to another in our genome and sometimes landing in the middle of an essential gene causing it to mutate?

I can only think of two reasons, if you can call the second one a reason. Malevolent intent or mindlessness. Perhaps a creationist can suggest a benevolent reason for it because I can think of none whatsoever.

Apparently, these short 'jumping' genes come in two forms. Both need a 'tail' of a short stretch of multiple copies of adenosine (poly(A)) so that a protein called ORF2p can attach itself to the gene to help it insert itself in random places in the genome. In fact, LINE-1 also makes another protein, ORF1p; both proteins are needed. However, according to a paper published in Molecular Cell by a team from the University of Michigan Medical School and the Howard Hughes Medical Institute, only one form of jumping gene (LINE-1) has the DNA code for making this ORF2p protein. The other - Alu - acts like a parasite on LINE-1 and pinches the ORF2p protein because it doesn't have it's own code for making it.

The human genome is littered with broken forms of these jumping genes which have lost their tails and so lost their ability to relocate. They, like the jumping genes themselves, simply replicate when the genome replicates, doing nothing at all other than making copies of themselves. They account for a considerable bulk of the 'junk' DNA we all carry around for no purpose whatsoever except making copies of itself. They are not viruses because they don't move from host to host or subvert the cell's DNA replicating mechanism simply to make copies of themselves. They just get replicated like regular genes.

It is quite easy to see how, given enough time, this system could have arisen by random chance as an accidental byproduct of normal cell processes and, judging by the number of them scattered about the genome which have been neutralised, has been a fairly common occurrence. Then a different form of the gene loses the ability to make ORF2p but can still work because the 'normal' version does that for it. So, we have a parasitic form of the jumping gene living off the normal form.

Of course there could be other equally plausible pathways by which this could have arisen, none of which require magic, and, if the frequency of mutations produced by it remains low, there will be little selective pressure to evolve mechanisms to counter it. Voilá! We not only have our genome not only doing something entirely pointless, but we have something which parasitises it. And just because our genome replicates itself slightly imperfectly.

So, to give an 'alternative' (i.e alternative to explaining it) explanation to selfish gene evolution, why would an intelligent designer design something that can only be harmful to us, then make another version but make it so it needs to steal an essential component of the first form making that non-functional, to do the same thing? An utter fruit-loop, maybe?

What definition of the word 'intelligent' do you use when you attribute the human genome to an intelligent designer when it has examples of mindless, or at best malevolent, idiocy in it such as these jumping genes?

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