mfaber

Well, well, I see Vander still hasn't answered. Not a real surprise, since this is the 2nd and sometimes the 3rd time this information has been posted, directly in response to Vander asking for good mutations.

Here is an article debunking Wieland who says the same things as Vander, there are no good mutations, that mutation in leads to a degradation or "loss" of genetic information, and that there are no mechanisms for increasing genetic information.
<a href="http://home.austarnet.com.au/stear/wieland_information_pp.htm" target="_blank">Dr. Carl Wieland is on the Wrong Train</a>, by Paul A. Poland.

There is a linked list of good mutations, mechanisms that "add" genetic information. Poland also drives home the notion that the terms "bad" and "good" mutations are really relative to the environmental requirements with the example of where a "mutational defect gives a survival advantage, e.g. the loss of wings on beetles on windy islands."

[ November 02, 2002: Message edited by: mfaber ]</p>

RufusAtticus

Well, it's been a few days. You have the information on HBB-C that you requested. Do you have a response?

Godless Dave

bumped for Vanderzyden and anyone else who wants examples of beneficial mutations.

Wyz_sub10

Did you get the licence plate number on that vehicle? Damn hit-and-runs.

[ November 05, 2002: Message edited by: Wyz_sub10 ]</p>

picklepuss

Not being a geneticist, I don't understand the concept of "frame shift mutations", (as per "the nylon bug"), at least not as regards their origins and the mechanism of change that completes the 'frame shift'. Is there a biochemical signal that initiates the process, or does it 'just happen', without any cause at all, or do we simply not know of any specific biochemical train of causation at this time?

If anyone should be kind enough to respond, please do not be too technical, as that would only confuse me further.

pz

It doesn't require a biochemical signal, and it does "just happen". It is not as if there is no known cause, though.

One simple example is a deletion. DNA is a chain of nucleotides linked together; imagine that something like a gamma ray strikes the molecule knocking a couple (or a lot) of nucleotides out of the chain. The cell tries to recover and repair by stitching it back together, but there may be missing bits, and there may also be that frame shift. In the coding regions of the DNA, the sequence is meant to be read precisely 3 nucleotides at a time. If a deletion takes out some number of nucleotides that is not a multiple of three, the reading frame will be out of register.

For example, if the sequence is supposed to be

AAA CCC AAA CCC

and the 2nd and 3rd "A"s are lost, it will then read

ACC CAA ACC C

That's a frame shift. It turns an entire long sequence of DNA into gibberish as far as the cell is concerned.

There are other kinds of copying errors that can also cause deletions and insertions that lead to frame shifts; ask if you need more information.

Oh, I should add that it doesn't always produce gibberish. It sort of randomizes a sequence, and sometimes, as with the nylonase mutation, that random chunk fortuitously has some novel function.

[ November 05, 2002: Message edited by: pz ]</p>

MortalWombat

<a href="http://www.orst.edu/instruction/bb331/lecture02/Figframeshift.html" target="_blank">This</a> page has a simple schematic explaining frameshift mutations.

Gooch's dad

Excellent thread!

I'd like to point out something to those that think this thread might just be to 'argue with Vanderzyden' or some such.

The lurkers such as myself are getting a TON of good information from the discussion, regardless of whether Vanderzyden disappears. Since Vander has dematerialized off this thread, some great information has been posted, especially the bits about the CCR5 gene and AIDS resistance.

Remember the lurkers! I love reading about all areas of science and my beginners understanding of evo biology is helped tremendously by threads such as this.



-Kelly

GeoTheo

Vander,
All I can say is take a genetics course at State Institution and found out how genetics work. You will soon become a theistic evolutionist.

picklepuss

Hi pz,

Thank-you for your kind and very rapid response to my questions. I'll just read through it for difficulties, if I may.

Ok, if I understand you correctly, the frame shift is brought about by an errant gamma ray. Has this been documented? I mean, I know gamma rays are real, and that they do cause mutations in DNA, but how would that prove that every time there is a mutation in DNA, it was caused by a randomly occuring gamma ray? Or some other radiation or toxic substance? I guess what I'm asking is, how do you know that a possible cause is, in fact, the actual cause?

Now in the nylon bug example, for instance, are you saying that a randomly arriving gamma ray just accidently struck that miniscule part of a genome which, if so struck, could frameshift the genome in such a way that beneficial, that is, adaptive, change would happen to that particular organism? And not just any change, but one which, by sheer coincidence, happened to a colony of bacteria residing in a nylon choked environment, and hence could put it to good use? I mean, I suppose these kinds of fortuitous coincidences are possible, but is it scientific to take them for granted? That is why I ask if they have ever been documented. Or is the radiation cause merely supposed?


OK, I see that. DNA is a code, knock out the proper arrangement of symbols and it will no longer scan. Instead of information only meaningless gibberish can be read from it. That's what I thought. So how does the gibberish get expressed in the organism? From what I've seen of mutants, it's not pretty, if that's what the results of frameshifts look like. Mutants sure look like organic gibberish to me.

But that's not a problem for me. That makes sense. What still isn't clear is why gibberish should ever be meaningful? Even once? It seems self-contradictory. But if a frameshift does not produce meaningful gibberish, how could it then go on to result in a meaningful, adaptive change in the organism? This is where I'm really confused, I guess.

Well, that's just it. With respect, I have to say that coincidence, luck, and so forth, just don't seem very good answers to my questions on cause and effect mechanisms. Especially when they are used to overide and contradict the normal course of events as empirically, consistently, and frequently, observed.

I may be wrong, but to explain evolution and adaptation as matters that reduce themselves to coincidence and lucky chance does not seem very useful. How is that any different from saying "The bacteria god did it!"?

Thanks again for your kind response, but, as a layman, I still don't get it.

[ November 05, 2002: Message edited by: picklepuss ]</p>