Data, Information, and all that....

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If you mix NaOH and HCl in solution you will get table salt (NaCl). You can stir the solution all you want, as vigorously as you want, in whatever direction you want, for as long as you want, completely randomizing the arrangement of matter, and you will still end up with salt. If you did the same things with a human cell you’d kill it.

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If you jumbled up all the proteins in the cell and left the DNA alone (the precious information), the cell would die. Compartmentalization is as important in cells as it is in chemistry. Try and make a battery work by mixing the anode and cathode solutions together and touch the anode and cathode together in the resulting mixture. Separation is important both for chemistry and life.

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At the least, you’re missing the forest for the trees: changing base sequences in DNA is changing the information content.

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In this thought experiment, each nucleotide acts chemically exactly the same after the order of bases was changed as it did before. G still bonds preferentially with C, using 3 hydrogen bonds; and T still bonds with A, using two hydrogen bonds. The polymerase enzymes would still interact chemically the same with each base also - but the polymerase would no longer bind at the right sites, because the order of bases was changed — you know, the information was altered.

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Changing the sequence of bases in the DNA polymer changes the chemistry. The information in DNA IS chemistry. So yes, changing the chemistry changes the information. If you change a substrate so that an enzyme no longer recognizes it you have changed the chemistry of the substrate. This goes for RNA polymerases as well as dehydrogenases. Are you going to argue that if I change sucrose to cellulose so that the an enzyme no longer recognizes it that I haven't changed it chemically but only informationally? So what if I change a base sequence so that an endonuclease no longer recognizes it I have changed the information but not the chemical? I can also change the sequence of one ssDNA so that it doesn't bind with the same affinity to another ssDNA sequence. This is a chemical property, but you claim that it is only informational. I say that the information in DNA is chemical, and only chemical.

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[From DNAUnion's quote] Changes in the intergenerational communication of genetic information result from mutations (see noise) and are the target of natural selection (see evolution).

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So the information involved is purely natural, and the information can change due to natural mechanisms. This is a far cry from the type of information involved in human:human interaction, or even machine coding. So I would say that the information content of a genome is a result of natural mechanisms and is not meant to convey information to another sender, but only receive information from the environment through natural selection. Therefore, the information in the genome is derived from the environment.

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I hope you are not claiming to counter me there. Remember, my point in these threads was never about HOW the information got into DNA, just that it IS there.

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I am trying to differentiate two types of information, spoken language and DNA. I will agree that there is information in DNA, but that it differs greatly from information used in language and in computer programming. In DNA, the information is transferred chemically and only communicates through natural selection. Human language is not physically based, instead language is based on abstract thought and is independent of the medium. With DNA, information is dependent on the medium, a sugar/phosphate backbone with attached nucleotides.[This message has been edited by Loudmouth, 03-10-2004]

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On the other hand, it appears to me, as it has appeared to most others, that DNAunion's quotes of uses of the term "information" in a biological context do not refer to Shannon information, i.e., are not using the term in an information theoretic context. While the context of the article *is* technical, the topic isn't information theory or even related to information theory, and their use of the term "information" is casual and everyday.

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Couldn't agree more. I have conceded that DNA can store information, but this info is different than that found in human communication and computer programming for instance. Information in DNA is not meant as an abstraction, but rather as a chemical reaction that is controlled by environmental selection pressures. The information in DNA can be read and understood by understanding the results of such pressures, that is the accretion of beneficial and neutral mutations as a result of natural selection.In common usage, information in these quotes is used as an analogy to computer code resulting in "commands" being carried out. However, it is only used to illustrate the chemical process and is not intended to confer attributes of intelligently derived communication or programming to DNA.

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Peter indeed it is a "far cry" but if one were able to use vicariant species distributions and DNA alingement gaps to PREDICT differential distributions of procaryotes in the solar system then I think we have to ADMIT the idea of information IN there those genes etc.
  —Mr. McFall

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This is the type of information that I think exists in genomes. We could compare tree ring temporal thickness across mountain ranges to guage annual rainfall across a geologic range and come across the same information. However, I think we can all agree that a single tree ring does not contain contain information. It is when humans start comparing between genomes that information arises, there is not intragenomic information in this sense. The information in DNA is due to selection on variation, and this information can be understood by cataloging changes in alleles across populations, and even across speciation events. On this we can agree.

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Okay, so what's my position on how the information got into the common ancestor...undirected evolution, of course. The LUCA is believed to have existed long after life originated: long after "random" mutation and natural selection were operating on living entities.

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LUCA could be the same as the human mitochondrial Eve. Even though there were human females before the mitEve, that mito. line is still the common ancestor for all humans. In this context, it is easy to accept LUCA as the first common ancestor, but not the first life. Information due to evolutionary mechanisms would already be present.However, my question is this. Is there a baseline information content for a random sequence of DNA. To be more exact, if we came up with a random open reading frame, with an appropriate promoter, would we expect some kind of activity from the translated protein? Even though this random protein may not have enzymatic or catalytic properties, I would bet a hundred bucks we could find something that it bound to. Perhaps the baseline information content of any DNA sequence is its ability to be transcribed and translated. Perhaps the earliest DNA information was actually a promoter site and the lack of stop codons. Just a thought.