Anonymous
Anonymous asked in Society & CultureReligion & Spirituality · 1 decade ago

Why does mutation necessarily lead to a loss of genetic information?

Surely there are ways in which DNA can be imperfectly copied which extend the length of the sequence, thereby allowing more information to be stored.

For instance, the phone number 02082087080 could be mis-copied as 02082082087080 ..... and there is an analogue among the possible modes of gene misreplication.

As long as the organism with the mis-copied DNA survives, there is now surely an opportunity for *more* information to be preserved in its DNA than in its parents' DNA?

Update:

Chicken Little -- every creationist website states, and every creationist blindly parrots, that mutation is invariably a loss of information; but they never elaborate as to WHY this is the case. I think that an extraordinary assertion requires extraordinary evidence.

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  • OPM
    Lv 7
    1 decade ago
    Favorite Answer

    In the meaningful sequences of genes, each codon is uncorrelated with other codons, which means it looks like white noise, or essentially a random sequence. To convey the highest amount of information in the smallest amount of space, each piece of information should be orthogonal. This would appear no different than a random sequence. Dropping information, if there is proof reading, should not automatically result in a loss. But let us assume data is added instead. A mutuation increases the information. For it to actually increase information, the added codons must be uncorrelated with the other codons. If they were correlated, then some or all of the information would already be in the other codons.

    So let us assume it is uncorrelated, essentially white noise. There are three possibilities for this white noise. First, it really could be meaningless noise, in which case the codons exist but do not code any protein. This is no different than if the mutuation did not exist. Second, it could code a deletarious protein and either kill the organism or make the reproductive line less successful, essentially committing genetic suicide by selection. Third, the random sequence could be useful, in which case, it would add information and if it led to increased reproductive success in the line, would become a permanent feature of the species or even cause a new species under certain circumstances.

    You can see the association between randomness and information. Correlation implies the information already exists and therefore the information is wasteful. Only uncorrelated information is efficient. Uncorrelated information looks like Gaussian white noise. Since chemical mutations are essentially Gaussian white noise triggered by the Second Law of Thermodynamics, the only way valuable change can happen is through chance events. The selection process then skews the distribution so that even though most mutations are not helpful, the helpful have a statistical survival advantage that makes it more likely to propogate.

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  • 1 decade ago

    Mutation doesn't occur by adding new information. It happens when the bit of information located on one gene is changed. It's more like if you change the 2 in your phone number to a 5. That means the original information carried by the 2 is lost and replaced by the information on the 5. But not all, in fact very few, mutations cause the death of the organism. Mutations occur all the time. Most mutations make a change so small that little function is changed or lost. It's only when a mutation either destroys the function of the organism or allows the organism to change in some way that helps them adapt to their environment that the change is important.

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  • Sonny
    Lv 4
    4 years ago

    It isn't mutations by themselves that cause an increase in genetic information. It is mutations combined with natural selection. Here's a similar example that might help you understand the concept. Imagine there is a casino in Las Vegas with a row of 10,000 slot machines. The owners have hired a mechanic that knows how to make exact duplicates of the slot machines. The owners have also decided that every day they will throw out the 5 least used slot machines and have the mechanic build exact copies of the 5 most used machines. You may assume that this would have no effect on the odds of winning at the slot machines in the casino. You would be wrong. Over time, the slot machines will slowly devolop wear and tear on their internal gears. Some will become more likely to stick on losing pictures. Others will become more likely to stick on winning pictures. This process of wear and tear is similar to mutations in DNA. Also, people at the casino will choose to play more often at the machines that have a higher chance of winning and they will avoid those with a higher chance of losing. This is similar to the process of natural selection in nature. When these two processes are combined, it is easy to see that the odds of winning at the slot machines in that casino will steadily rise because the losing machines will be thrown out and the winning machines will be copied. Apply the same idea to nature and you can see how the process of evolution enables an increase in genetic information.

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  • 1 decade ago

    Virtually all observed mutations are in the category of loss of information. This is different from loss or gain of function. Some mutations can cause an organism to lose genetic information and yet gain some type of function. This is rare but has happened. These types of mutations are often called beneficial mutations. For example, if a beetle loses the information to make a wing on a windy island, the mutation is beneficial because the beetle doesn’t get blown out to sea and killed.

    Never in the history of science has any mutation benefitted an animal's species long term, or made it more genetically complex. Evolution would require billions of these mutations to be happening constantly both today and throughout history, and yet none have ever been observed. All mutations ever witnessed in reptiles, birds, or mammals are either a loss or a scrambling of existing genetic information, and are either neutral or negative to the mutated animal.The bottom line is that natural selection, by itself, is powerless to create. It is a process of 'culling', of choosing between several things which must first be in existence. There is no known natural law through which matter can give rise to information, neither is any physical process or material phenomenon known that can do this.

    • B5 years agoReport

      Natural selection does not need to "create", it needs to "select" - and that's exactly what occurs in your example with the beetle. In your narrow view, the beetle becomes "less of a beetle", but its entire set of genes make a net gain in survival.

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  • 1 decade ago

    Where did you get the idea that the result was always a loss? Certainly DNA sequences can expand; after all, do you expect an amoeba to have as much DNA in terms of sheer numbers of genes as a human being?

    But don't assume that "more" means "better," either. If DNA is bad, it doesn't matter how much you have.

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  • 1 decade ago

    More sequences don't necessarily lead to more information, per se. In this case, the insertion is more likely to be junk DNA than anything else. Provided it did not harm the organism in relevant ways, it would still be passed on to offspring, but wouldn't see a particularly large spread through the population if it conferred no useful trait.

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  • TTAGGG
    Lv 5
    1 decade ago

    There are proof readin mechanism and DNA repair mechanisms in place to prevent any mutation. Of course, they may not work perfectly due to diseases, and that usually end up in cancer. Now, cancer is a real evolution. Because it kills off people who have mutation.

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  • 1 decade ago

    Some genetics are weaker than others and by natural law are required to not be copied.

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  • Anonymous
    1 decade ago

    Extra information doesn't always mean a good thing. [not in genetics]

    Example a person with an extra chromosome.

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