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Johnies Zaoudis

MSc Student, University

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Are we sure that DNA is making errors?

When David and biologist in generally say that DNA is making errors i think they see it only from the "copying" perspective. Could it be that this is in purpose or is there a proved theory that it happens due to failure? Is DNA trying to support the proliferation of the tolerant or some kind of evolution in species?

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  • Apr 30 2011: I think that it is simply errors. I say that because if it was not an error (ie: it was intentional) it would mean one of two things:

    1. DNA is sentient

    or

    2. DNA was designed
    • Apr 30 2011: And if it wasn't "an error" it would be perfect(i.e. no mutations).

      I don't think there is a proven theory per se, that there is isn't something in DNA that wants to mutate(failure to copy) I think that it is really just assumed because so many(the vast majority of) mutations are non-beneficial.

      You could get into a whole pHiliZoPHiGal argument about how the DNA might somehow "know" or "want" to mutate as to "consciously" build towards evolution but that argument won't go anywhere.

      ... But hey you have the Masters I'm just a lowly undergraduate ;)
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        Apr 30 2011: Actually that was what i had in mind too...
      • Apr 30 2011: DNA is a molecule and therefore subject to chemical reactions. Hydrogen Bonds, bond nucleotide chains together and therefore DNA structure is very susceptible to radicals(cation, and anionic compounds, polyatomic ions).

        It is pure physical law.
        Say I hold a stone over an open well. When I let go of the stone it will fall to the bottom of the well. We do not claim that the stone or the well are sentient, this is merely the effect of gravity on the stone.

        This is the same as with dipole-dipole interactions. Full charges from radicals overwhelm partial charges in the hydrogen bonds. I could get into a whole thing about acids and alkali's here but I don't think it is necessary.
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          May 6 2011: Hi Richard
          As always, amazed I am with your breadth and depth of knowledge , interest & analytical skill.

          Yes I agree all living beings are sentient though their basic designing materail DNA is not.

          Was just curiours whether you are particular about only plant and insect to be so.
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          May 1 2011: Hi Richard , good thoughts

          Considering nucleotide level of DNA , my thoughts favors randomness of mutation while going through replication in changed or even unchanged environment

          What do you think?

          Thought a bit so editing the post , what thoughts are there to be particular about insects & plants to be sentient Richard ?
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        • Apr 30 2011: Debra,
          The caterpillar adapted eyes in this way...
          At some time a caterpillar had little blotch pattern on its coat. This made the bird slightly less inclined to attack it, because of fear, after all why risk it for that caterpillar when other non-threatening caterpillars are everywhere. Then that caterpillar had offspring which may or may not have had the blotch, if they did maybe the blotch looked slightly more like an eye maybe it didn't, but eventually throughout the generations the caterpillars with the "eye blotch" were less and less likely to be eaten because the birds were afraid of them, therefore they more than the others who did not have the "eye blotch", survived long enough to procreate. The caterpillars without the "eye blotch" were then more likely to be eaten because if the bird is afraid of the "eye blotch" those "eye blotch" caterpillars have been taken off of the menu for the bird. Kind of like if I had 5 burgers 2 without and 3 with mustard, but you didn't like mustard, you would then be more likely to eat the 2 without.Insects procreate rather quickly and so you could see how incremental steps could get you from not having the "eye blotch" to having one that looks pretty precise, even though in the beginning it was just a blotch.
          I hope this isn't too confusing
          If you would like me to explain how the Sickle-cell adaption works I will in another post.
          Error and adaption are relative terms, if the mutation is beneficial we call it an adaption, if is not we call it an error but in essence all mutations are "errors."
          I think the intuition for this might be difficult because it is hard to strip the entire process of any purpose.
        • May 1 2011: I'm not sure what level of detail you want here or if you know what sickle cell actually is so I will try to describe this in some basic fashion.
          Sickle cell disease is caused by a mutation that affects one part of the protein complex that makes up hemoglobin. Specifically we are interested in Hemoglobin S,C,E and a- and B-thalassemia as well as a couple of other protein mutations related to blood.
          Sickle cell causes clots during states of oxygen deprivation, and people with sickle cell are then vulnerable to kidney failure.
          So how does this adaption both survive long enough to cause an almost immunity to malaria and yet at the same time kill the host?
          I am hoping you are familiar with the differences between recessive and dominant alleles.
          People who have one gene for Hemoglobin S etc. and one for say A, neither die from the recessive disorder or malaria because they are effectively able to produce both the "anti-malaria" Hemoglobin S and the normal A. Therefore they can fend of the malaria and yet are not overwhelmed with the Hemoglobin S, which cannot sufficiently carry oxygen throughout the body.
          Since the sickle cell gene is heritable we can bet that it is a germ-cell mutation, meaning a mutation of the sex cells that lead to embryo formation. Interestingly enough you'll find quite a bit of mutations of the germ cells, the thing is mutated sperm usually are not the fastest swimmers.
          So here we are again with the caterpillar. One person was born with a recessive gene for sickle cell and maybe it was dormant for them but eventually over long periods of time two people with the recessive gene had kids and that kid may have died of sickle cell. BUT since Afrika and SE Asia are so malaria ridden, people with only one gene, or a recessive gene were somewhat immune to the disease, and therefore had a greater chance of surviving long enough to procreate, and therefore the gene doesn't die out.
          So you are left with a bad thing that does a good thing.
        • May 1 2011: If you would like to understand how an inability for blood to transfer oxygen around the body is related to the malaria parasite...

          Get a textbook!(LOL)

          Or go to this quick article that is exactly what you are looking for.
          http://sickle.bwh.harvard.edu/malaria_sickle.html

          Just get over your natural inclination to look for intention in the process and it will make clear sense.

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