Posted: Jul 05, 2010 1:45 am
by CharlieM
I wrote:
And if the hook protein FlgE had no functionless precursors what was the path in the diversification between it and its homologs?

Rumraket replied:
This question assumes the precursor must be functionless. Which is ludicrous and flatly wrong. Whatever the precursor proteins function was, as the entire precursor system started serving a motility function, the hook-precursor protein was under selection for increased functionality, in this case successful transfer of torque without breaking. Those that failed, died, those that succeeded didn't


I pose a question asking what must happen given that there is no functionless precursors (sorry for the double negative) in other words a function is assumed in all precursors on the path from common precursor to FlgE and its homologs. You then say my question assumes the precursor must be functionless. You must have read me wrong.

PhiloKGB:
Ah, the fallacy of never-enough-detail. The underhanded creationist takes refuge here because he knows that biologists have neither the resources nor the inclination to reverse engineer a pathway for every feature. Moreover, they have absolutely no intention of doing so every time a creationist issues a poorly-considered challenge.


But I'm not asking for a suggested pathway for every feature, just for FlgE. As homology is so prominant in Matzke's proposed flagellar evolution, surely he could look into the details of just one pathway as an example.

Rumraket:
We cannot go back in time and witness events at the molecular scale, and because we can't do that... that's where the designer is hiding.


You said it yourself, we cannot go back and witness these events. So to state that FlgE and its homologs developed from an unknown precursor through the selection of unguided random events is unfalsifiable and therefore not science as most here see it.

I wrote:
And there is no evidence whatsoever of a pre-existing universal joint being co-opted and slotted into place in the drive train.

Rumraket replied:
Which is not the proposed model and therefore a strawman.


I never said it was the proposed model. I was clarifying that, unlike the TTSS, the hook is not available to be co-opted from elsewhere and so it would seem that it appeared due to the modification of a pre-existing protein. The question is, was the route taken guided or fortuitous? Most people here would say that it was fortuitous but no one has gone into what amino acid changes would need to occur for this to happen. We know the amino acid sequences of FligE and its homologs so we know the sequence differences. Several of these differences will have a minor or no effect in the function of the protein but there will be a vital few which make all the difference. Steps of single amino acid changes along the path are not going to result in a functional protein for every step. So in order to retain functionality, multiple amino acid changes will have to occur together. And changes will have been co-ordinated between the hook protein and related proteins such as hook associated proteins and regulators in order to retain a functioning unit. All this reduces the plausibility of chance events being the cause of the change into a functional universal joint.

Hotshoe writes about the hook:
our perception of the "hook" is colored by the very word itself.

Well mine isn't when I consider the flagellar hook. As far as I'm concerned a hook is a far more simple structure than a universal joint and so the term 'hook' doesn't do justice to the joint in question.

A few evolutionary facts have been given which I presume are supposed to argue against my position. The ones I can recall are:
A monkeyflower turning into a monkeyflower, a peppered moth turning into a peppered moth and hydrogen producing bacteria turning into hydrogen producing bacteria. I have no problem with these examples of evolution.