Archive for September, 2010

Did DNA Copying Errors Create Systems for Preventing DNA Copying Errors?

Posted in Creation/Evolution on September 12, 2010 by Dave

I recently studied DNA replication and was amazed to find out that all free living organisms have astoundingly sophisticated DNA copying error correction systems. And it’s not just higher organisms that have these systems. Even the lowliest bacteria has a highly sophisticated system. Bacteriologist James Shapiro writes …

The first point is to recognize that bacteria are far more sophisticated than human beings at controlling complex operations. The fast-growing bacterial cell is the ultimate just in time production facility. When an E. coli cell divides every 20 minutes, exquisitely reliable coordination has been achieved for hundreds of millions of biochemical reactions and biomechanical events. E. coli cells replicate their DNA at almost 4000 base-pairs per second but have an error frequency of far less than one nucleotide misincorporation per every genome duplication (2 X 4.6 million base pairs duplicated every 40 minutes; Cooper & Helmstetter, 1968; http://www.genome.wisc.edu/index.html). This incredible precision is accomplished not by rigid mechanical precision but rather by using two layers of expert error monitoring and correction systems: (1) exonuclease proofreading in the polymerase itself, which catches and corrects over 99.9% of all mistakes as soon as they are made (Kunkel & Bebenek, 2000), and (2) the methyl-directed mismatch repair (MMR) system, which subsequently detects and fixes over 99% of any errors that escaped the exonuclease (Modrich, 1991). Together, this multilayered proofreading system boosts the 99.999% precision of the polymerase to over 99.99999999%. At both stages of the error correction process, detailed molecular analysis has clarified the distinct roles of sensory and repair components. In the case of the MMR system, the sophistication is even more impressive because the molecules discriminate newly replicated from old DNA so that they only correct the newly synthesized strand (Radman & Wagner, 1988). Link to paper

I also investigated viruses and found that some viruses probably do have some sort of error correction systems and one virus researcher I queried said she believes that ALL viruses probably have some sort of error correction system.

Anyway, I got to thinking about error correction and evolution and it seems rather odd to me that the very thing that supposedly created all of life on earth — random mutations in DNA — is vigorously guarded against by the cell. All cells on planet earth are working very hard to prevent the very thing that supposedly created them!! Think about that!! If that isn’t evidence against the non-ID view of Origins then I don’t know what is.

Anyway, I presented this information at the TalkRational.org forum where a number of professional scientists gather to debate Creation vs. Evolution issues. One of them, a virologist, agreed that genomes larger than about 15kb (kilobases) wouldn’t be viable without error correction. He believes, obviously, that error correction systems had to evolve at some point in life’s history therefore he believes that there would have had to be a time in history when there were NO organisms with error correction systems. The problem with this view is that the only organisms alive today that (perhaps) don’t have error correction systems are viruses with genomes smaller than about 15kb. But viruses  cannot replicate without a host (i.e. a much more complex genome which would have required error correction).  So we have a problem.  This virologist can only believe — on faith — that there must have been some sort of free living ancient organism with a genome smaller than 15kb that could somehow self replicate. But there is absolutely no evidence available to us that any such organism ever existed.  And of course nothing remotely close to such organism exists today.

So which is more likely? That such a fantasy organism (shall we call it a virusoid?)  DID exist contrary to all known facts?  Or that an Outside Intelligence created life? Well … I pick the latter because that view is based on actual experience, i.e. we have experienced Higher Intelligences (humans) creating complex entities.  Fantasy Organisms like “virusoids”, flying horses, mermaids and centaurs are well … Fantasies.  Link to Talk Rational Discussion on this topic.

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