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Are DNA and enzymes related?

  1. Aug 10, 2018 #1
    Does the human DNA contain information that could, combined with other data, tell what kinds of chemicals will their digestive system process or not? For instance, there are people that have hereditary fructose intolerance (not to be confused with fructose malabsorption).

    Is such a lack of an enzyme discoverable through the human DNA? To be more precise in the question, does the DNA contain information defining what enzymes will one human have, be deficient, or lack completely? Are DNA and enzymes related?
  2. jcsd
  3. Aug 10, 2018 #2


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    The structure of all complex proteins are encoded in the nucleic acid sequence of their DNA.
    The DNA directs the formation of mRNA which in turn directs the production of proteins by the ribosomes.
    This is called the central dogma of molecular biology.

    The information for making all of your proteins is encoded in your genome.
    The structure of the proteins enbodies much of what they can do (as little nanomachines).
    They can get structurally (chemically) modified by other proteins which can change their abilities, but, in a sense, this can be seen as an ability present in the combination of proteins present in different parts of the body.
  4. Aug 10, 2018 #3

    jim mcnamara

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    Some changes are epigenetic - induced by the environment. Some sites on the DNA chain that can be turned off, on, partially on - By the addition or removal of histones. Methylation (addition of a methyl group) on other DNA molecule sites can have similar effects.

    So the phenotype - what you see as the actual genome expression - is under the general control of DNA, with additional changes in transcription (DNA->mRNA) due to epigenetic changes. These can result in the partial expression of a gene (called penetrance), or turning a gene off completely. And not all DNA is altered like this. Meisosi remove most, but not all, epigenetic changes.

    Epigenetics applied to your question means: changes to the structure of, or altered production levels of, an enzyme.

  5. Aug 11, 2018 #4
    Encoded? Has someone made a decoder for it? To make sense of the 'encoded' data?
    Is that turned on/off/partially-on permanently or temporarily during a specific process? If the answer is temporarily, will it always happen in the same process or can it sometimes not happen?
  6. Aug 11, 2018 #5

    jim mcnamara

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    Yes. DNA is a code. It uses four different molecules placed onto a strand together: Adenine, Thymine Cytosine, and Guanine (A, T, C, and G).

    A sequence of three of these is termed a codon. Like some letters in Morse code are specified. Each one specifies the position of an amino acid, per the order of codons. List of codons: https://en.wikipedia.org/wiki/DNA_codon_table Note the amber, ochre, and opal codons. They are "stop", not any amino acid.

    Humans have co-opted the DNA code to encode human alphabets. See digital data storage: https://en.wikipedia.org/wiki/DNA_digital_data_storage

    Instead of a series of questions about DNA/epigenetics consider a really good explanation in this video from the Royal Institute

  7. Aug 11, 2018 #6


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    The answer to all the questions of your second paragraph is 'yes'. Your own first link Is giving you an example of a known enzyme defect caused by known DNA alterations, possibly you did not have enough background to understand this. In many cases the DNA locus, the gene and its alterations have been found by the techniques of molecular genetics (applied to families, descendancies and populations). In the case of a relatively "easy" enzyme like this I would guess that the enzyme deficiency would have been found first more directly by biochemistry which pretty well indicates where to look.
    Last edited: Aug 11, 2018
  8. Aug 11, 2018 #7
    I'm a little lost here. I got the answers for my questions which pretty much solves the thread, but why epigenetics was introduced in the subject? The example I gave is not a heritable phenotype change due to the environment. As far as I understand, it actually involves DNA sequence alteration. For much I re-read, HFI does not appear to be epigenetic.

    Unless the reason epigenetics was mentioned was to let me know that while DNA and enzymes are related, there might be times when a relationship cannot be established just with those two since the environment may be also playing a factor in the generation of enzymes. Like sort of telling me:

    "Yes, you might be able to find through DNA whether a human will have the necessary enzymes for processing certain chemicals in their digestive system, but not always, since the environment may change the expression of the genes and hence, affect the generation of an enzyme."

    Am I understanding this correctly?

    P.S. Great video.
  9. Aug 12, 2018 #8

    jim mcnamara

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    You got it. Just because the gene is in DNA does not mean it expresses itself. Epigenetic effects are prominent among the reasons why gene expression is turned off, or limited some way. Like the gene is expressed only in certain tissues of an organism.

    You may have heard of the older model, still taught in introductory courses. It is Mendelian genetics which talks about and introduces the dominant gene and the recessive gene concept. Epigenetics is another newer model. On top of that older one.

    <edited, bad grammar fixed, maybe>
    Last edited: Aug 13, 2018
  10. Aug 13, 2018 #9
    Thank you then. I learned something new with all the answers in the thread :approve:. Glad I asked.
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