Wednesday, June 16, 2010
Yes, this shit is so amazing that it makes a hardened evolution theorist like me cough up some creationist thoughts (don't worry, it will be a temporary affliction).
This animation shows the lagging strand replication process in greater detail. If you are wondering why the lagging strand should have to be built in reverse, it is because the other side of the helix is inverted which would have necessitated an exact molecular machine to have been evolved from scratch, but in reverse! This molecule, "polymerase", is composed of 8005 atoms. The ingenious workaround, to run the strand through the same molecule backwards, though mechanically awkward, is far more likely (less complicated) to have evolved than would have been a mirror image of the whole polymerase molecule (or its function). In fact, it is probable that such a molecule might not even be physically possible given the "handedness" (right/left) of the atoms molecules must be built of. Because of this, I consider the asymmetry of DNA replication machinery to be evidence of the least energy dictated meandering of the evolutionary process.
By pure chance, an particular arrangement of 8005 things would happen once every 8005 to the 8005th attempts (8005 factorial). Of course molecules don't assemble by pure chance. Even if you dumped the requisite atoms into a box and shook it up, the assembly wouldn't happen instantaneously, some atoms would form small groups, and those groups would clump together into larger groups, etc. The atoms of each element have unique properties that effect their aggregation.
But that isn't the full story either because the polymerase molecule is built atom by atom by DNA.