Daniel Boyd

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Does the genome contain enough information?

The genome contains precisely the information needed to produce the collection of proteins contained in the cells of an organism - no more. It therefore has no information left to determine the entire three dimensional structure of the organism, its organs and cells. Please explain why this is not true.

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    Sep 26 2013: odd question... As you don't seem to include that we actually need our environment (including information from it) in order to develop and function as a human.

    There is also redundancy (otherwise, we could not have recessive genetic deficits).

    I think there must be "enough" information... or we wouldn't be alive, would we?
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      Sep 27 2013: That somehow living organisms are created is self-evident. The point is that all of the information contained in the genome is used to create proteins, So what puts the proteins together in the right order?
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    Sep 20 2013: From Wikipedia: "An analogy to the human genome stored on DNA is that of instructions stored in a book:
    The book (genome) would contain 23 chapters (chromosomes);
    Each chapter contains 48 to 250 million letters (A,C,G,T) without spaces;
    Hence, the book contains over 3.2 billion letters total;
    The book fits into a cell nucleus the size of a pinpoint;
    At least one copy of the book (all 23 chapters) is contained in most cells of our body. The only exception in humans is found in mature red blood cells which become enucleated during development and therefore lack a genome."
    You are asking for an explanation as to why it is not true that the genome is insufficient to control the "entire three dimensional structure of the organism, its organs and cells."? You are (rightly) admitting it is not a justifiable true belief so why not just go with that?
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      Sep 21 2013: I'm posing the question to challenge the contemporary (and understandable) assumption that genetics and heritability are synonymous because the genome is the only information that is physically transferred from one generation to the next.

      I thought it would be interesting to start a debate on the discrepancy between the amount of information in the genome and that required to define the three dimensional form of a multicellular organism.

      My question (to people who ascribe to the assumption) is therefore how they explain this gap. I'd also be interested to hear from people who hold other opinions on the formation of biological structure.
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        Sep 21 2013: So what essential biological information do you imagine is passed from generation to generation by other than genetic means, and what are those means?
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          Sep 21 2013: The information I am referring to is the entire complex structure of the organism that is replicated in each generation. It is the information that makes the difference between a random pile of proteins and other biological molecules and an operational cell/organism.

          My point is that I can't see that there is any space for this in the genome. I'm trying to find someone to defend that idea!
      • Sep 23 2013: Genome is NOT the only thing that is passed down through generations; to be on the technical side, what contains in the egg that get passed down from a mother to her child include proteins and RNAs and other stuff. The mother also provides an environment that can determine how the fetus is to develop. There is also genetic imprinting called epigenetic (a system that can turn off certain genes; it is not wholesomely understood yet) that can be passed down from either parent to the child. Genetics and heredity are NOT synonymous and that has been generally accepted in the scientific community.

        As to what make us what we are, this is more complex than simply our genome. The simplest example is the observation of identical twins growing up to be two separate beings with separate consciousness and thinking.

        I would say that the genome encodes everything that we are; we cannot make what is not encoded by our genome. Most of our genes are turned off and it is what is turned on that makes us what we are. But what influences these decisions are not completely understood.
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          Sep 23 2013: Thanks for your contribution, Tina, and certainly epigenetic factors are at work here. It is clearly of significance that the genome is not an isolated entity but exists within the controlled environment of a fertilised egg with various other cellular components.

          However, when it comes to quantities of coded instructions, the genome would seem to contain massively more specific information than this environment - and still doesn't seen to have nearly enough.

          Surely an epigenetic influence that turns off genes only reduces the information available, rather than increasing it?
  • Sep 20 2013: Actually the genome contains a fair bit more than the sequences of protein you find throughout the body.
    Most of it is what we call "junk" DNA, which either has no use or some use we don't fully understand (there are theories, but nothing 100% conclusive). So theoretically, you could trim out large sections of your DNA, and as long as they were carefully selected, there would be no adverse effect (though you may feel a bit lighter).

    Besides, the proteins to build things on a cellular level are plenty to determine the organism's overall structure. They interact with each other specifically towards that end. Enough micro-chemistry eventually adds up to bigger things.
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      Sep 21 2013: Nadav, this is the first method of 'weight reduction' I hear of which would probably work! lol

      And in case this wasn't intentional humor, please forgive me, as I agree with what you are saying here as well.
      • Sep 22 2013: Actually, I'd love to be able to run this sort of thing as an experiment, just to see what would happen if all the junk DNA just disappeared (though probably not on a human, at least until its deemed safe). It'd certainly help us understand what its there for.

        But even if there's no effect, I like the idea of making a killing off of turning "junk DNA removal" into a weight loss strategy.
        It'd be hilarious if nothing else.
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          Sep 23 2013: It is interesting how little we still know about our DNA and that we could only find out about 'junk DNA' by trial and error in removing it.

          But be quick in filing your copyright for this weight loss strategy, before ''Weightwatches' gets to know about it ... :o)
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      Sep 21 2013: Even if there was a mechanism by which non-coding sequences could get involved in this construction process, they would still contain insufficient information to specify every parameter of the morphology and physiology of a multicellular organism.

      You propose that there are plenty of proteins to determine the organism's overall structure, but there are no more proteins than their are genes. So still too little information.

      Certainly, proteins do build things at a cellular level (and cells combine to form multicellular organism). My question is why they do this in the specific way they do, rather than the myriad other ways that the same collection of molecules could arrange themselves.
      • Sep 22 2013: I think the problem lies in your understanding of the scale of things.

        The human genome is ridiculousness long. Scientists have calculated its actually a lot longer than it needs to be--as in, there is all the information required to make a human stored in every single cell, and then some.
        Proteins reaction on a miniature scale eventually scale up to bigger things. The protein reactions are numerous enough and complex enough for an entire large organism to form, no extra DNA required.

        Its like asking how does each individual worker working on a sky scrapper know how the whole building turns out?
        The answer, he doesn't. He just does the small part assigned to him and it all works out in the end under the supervision of a management system, comprised of other workers whose job is management. Proteins are very much the same. You have proteins "coordinating" the other proteins into structures much larger than themselves.
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          Sep 23 2013: The construction of a building is an interesting comparison that served to illustrate just what a challenge we are talking about. To start with, a sky scraper is a far less complex construction both structurally and functionally than even a singel cell, let alone an organism.

          More importantly, all of the information required to build it is explicitly available - in the blueprints drawn up by the intelligent architect that are used by the intelligent worker.

          The cell's proteins are neither intelligent architects nor intelligent workers, and there don't seem to be any blueprints around - just instructions for making bricks and girders. So how do the bricks and girders get put together in just the right way?