The Nature of Mutations

Hi Phospholipid, this statement is also inaccurate.

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I said that of the two catagories of mutations (neutral and deleterious, of which only the deleterious affect the phenotype), those which affect the phenotype damage whatever physiological character that incurs that mutation.

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They will always carry a deleterious affect,

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The differences in glyosylation which define blood types come from several well defined mutations.
mutations
Some of these changes in glycosylations, mutations within the glycosylating protein, can confer disease resistence
seminar on blood types
This is a well understood phenomina.------------------
"Chance favors the prepared mind." L. Pasteur
Taz

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even by science's standards [Kitcher], for the theory of evolution to be considered a valid theory.

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I am sure that Kitcher would be very interested to learn that his statements indicate that Evolutionary biology is not science .------------------
"Chance favors the prepared mind." L. Pasteur
Taz

Phospho, you really should not make statements like

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And the facts dictate what is and what is not. A genetic change is not a mutation if it is mediated by the organism. Period.

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when you are unaware of the "facts". Organisms mediate their own mutations, albet unwittingly, all the time. Please look at some of the articels associated with this one
here.
I have copied one abstract below.

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Palindromic DNA and Genome Stability: Further Studiesa
SUSANNA LEWISb,d, ERCAN AKGNc and MARIA JASINc,e
bProgram in Genetics and Genomic Biology, Hospital for Sick Children Research Institute and Immunology Department, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8 Canada
cCell Biology and Genetics Program, Sloan-Kettering Institute and Cornell University Graduate School of Medical Sciences, 1275 York Avenue, New York, NY 10021, USA

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This work was supported by a grant from the Medical Research Council of Canada and a Terry Fox grant from the National Cancer Institute of Canada (to S. L.) and a grant from the Pew Charitable Trusts (to M. Jasin). S. Lewis is a Research Scientist of the N.C.I.C.
dFax, 416/978-1938; phone, 416/978-4230; e-mail, lewis@immune.med.utoronto.ca
eFax, 212/717-3317; phone, 212/639-7438; e-mail, m-jasin@ski.mskcc.org

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Unusual DNA structures promote genetic instability. One such example is hairpin DNA, which can form from palindromic sequences and triplet repeats, and is also a characteristic intermediate in V(D)J recombination. We previously found that a large 15.3-kb palindrome that was introduced as a transgene into the mouse germline was highly unstable. Although it could be transmitted, the transgene was found to be rearranged in up to 56% of the progeny, and rearrangement events often involved deletion at the center of symmetry. Here, the fine structure of centrally deleted palindromes was sampled by analysis of recombinant junctions isolated from testes DNA, providing further evidence for a model, previously proposed, that accounts for such deletions on the basis of a hairpin-tip nicking activity. In addition to central deletions, gene conversion events were also elevated in the transgenic palindrome. We have now analyzed instability in two mouse sublines in which (as a result of inversion) the transgenic palindrome had been shortened to 4.2 kb. In these sublines, the transgene was still subject to both rearrangement and gene conversion events at a high frequency, similar to the original 15.3-kb palindrome. Recombination was not limited to the sequences constituting the inverted repeat, but was seen to include sequences lying outside the palindrome. As discussed, the salient feature in all of these observations, a high level of genetic change associated with palindromic DNA, underscores the significance of hairpin DNA and hairpin-tip nicking in genome stability.

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It essentially gives an example of organisms which have sequence mediated increases in copy errors, i.e. mutations. Many of the se mutations increase in times of stress to the organism which results in cellular stress and increased mutation. Most of this data is currently applicable to bacteria although there are many applications to multicellular and larger organisms also listed on this and other sites.And you never addressed my post in this thread re: blood type mutations and their beneficial effects, or are you calling a series of well defined mutations part of your variety which came pre-packaged by a diety who put the diseases in for the mutations to be beneficial for ?------------------
"Chance favors the prepared mind." L. Pasteur
Taz

More than anything else these stats represent to me the failure of the schools to teach biology properly. It also illustrates the pressure brought to bear on both public schools and on companies that make textbooks to delete as much as possible any substantive reference to evolution and the major theories explaining it within the public school system.Now, creationists will WHINE about their point of view not being allowed in schools (where,in a science classroom, it should not be anyway) while all the while trying to prevent the teaching of science in its proper place. Their mis-statements concerning evolution require an audience ignorant of the real theories surrounding evolution if they are not to be challenged.

[Non-substantive or off-topic post deleted. --Admin]

[This message has been edited by Admin, 05-21-2003]

[Non-substantive or off-topic post deleted. --Admin]

[This message has been edited by Admin, 05-21-2003]

Hi Mammuthus, Hi PPL. FYI PPL is a very old organic/physical biochem shorthand for PhosPhoLipid, hope that you do not mid if I use that for brevity.PPL, with respect to definitions of science I would like to refer you to Kitcher, the author who you mistakenly claimed did not support evolution as a valid scientific theory as well as books by others, here are a few into books on the philosophy of science and what constitutes science inthe authors view:one, two, and in a slightly upfdated form three. I am of the opinion that all students entering the sciences would benefit from taking at least one philosophy of science course to give them a better all-around understanding of what it is that they plan to do.Another short comment, after reviewing your comments re: mutations and the "control" of these mutations by the organism I have come to the conclusion that you are operating under a few misconceptions. Mutations occur with varying probabilities over both space (the location within the genome depending on the sequence) and time (ie, when the mutation occurs). Neither one of these probabilities appears to be fixed with changes based on responses to environmental stress. That is where some of the "non-randomness" statements of peopel such as Lee Spentner (sp?) come from. They are viewing all random events as equiprobable, this is not the case. When you view things as altered probabilities a pattern starts to emerge which has just started to be defined over the last 10 years or so. I would suggest Darwininteh Genome for an excellant overview, even if one does not totally agree with some of the authors conclusions.------------------
"Chance favors the prepared mind." L. Pasteur
Taz

Like mostother people in the field he has some very valid point but takes his arguements a bit too far, kind of like Popper. IMO, to use an analogy, the ground must in some way be fertile for an idea to take root. Where I think that Kuhn goes to far in that he seems to veer to the position that the different groups on either side of a revolution can not even undertand the other. If that were the case all revolutions would start from scientific ground zero, we would constantly be reinventing fire and the wheel.Oh, and in case certian pseudo-scientific "great men" or self annointed dieties try to use this, it does not mean that you can use this as an excuse for the non-acceptance of "scientific ideas" sans merrit.

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"Chance favors the prepared mind." L. Pasteur
Taz

Sorry for the typos. I have to do a snap presentation in an hour or so and am a little swamped.[This message has been edited by Dr_Tazimus_maximus, 05-21-2003]