DNA Sequencing

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This topic contains 5 replies, has 2 voices, and was last updated by  Delengroth 6 days, 1 hour ago.

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  • #30681 Reply

    Brandon Dozier

    It’s interesting to think about, but technically speaking every organism that has ever lived, and every organism who will live has their DNA sequenced in the Library of Babel. I was thinking about it the other day and because DNA is described with the letters ATGC, technically if you find enough pages of every organisms base pairs, you can find every single combination as far as I understand. Pretty neat.

    #30682 Reply

    Delengroth
    Participant

    Fascinating thoughts! I went and did some napkin math to see how many pages it would take.

    Since there are approximately 3 billion base pairs in human DNA, that’s 6 billion letters. However, if you recall from biology, you can only have A-T and G-C pairs. So, you really only need to store one half of the DNA double-helix, bringing us back down to 3 billion letters. Since each book is 3200 characters x 410 pages (1,312,000 characters), you can store any human’s DNA in 2286.59 pages, or about 5.58 books.

    Even more crazy is that all humans share about 99.5% of DNA with each other. If you wanted to know how many books it would take to store the DNA of all ~7.45 billion people on Earth today, you would only need to keep a copy of the 99.5%, and then add the pages for the remaining 0.5%. Let’s do the math!

    99.5% of 3 billion base pairs = 2,985,000,000 –> 2275.16 pages –> 5.55 books
    0.5% of 3 billion base pairs = 15,000,000 –> 11.44 pages

    I’ve been rounding up 2 decimal spaces, so 2275.16 + 11.44 still equals 2286.60 pages. If you glance above, I stated that any human’s DNA is 2286.59 pages. It’s close enough. Better to have more pages than needed, rather than not enough and have missing data.

    11.44 pages x 7.45 billion = 85,228,000,000 pages —> 207,873,170.74 books

    Since there are 32 books per shelf, and 5 shelves on a wall, and 4 walls in a hexagon, that means there are 640 books per hexagon.

    (207,873,170.74 + 5.55 books of the 99.5%) / 640 —> 324,801.84 hexes to store all of the DNA of every human on Earth right now.

    Of course, this ignores genetic mutations or diseases. However, to think that you’re only as unique as roughly 11 and a half pages from a book in the Library from any other human really makes you wonder how such a small difference can make such unique people, or maybe that whatever issues we have with each other are just as minuscule.

    #30686 Reply

    Brandon Dozier

    It’s super interesting seeing all of the math you did. It is quite amazing too that such a small percentage gives rise to so many different types of people. It’s also pretty crazy that even though there’s so many types of DNA that is essentially identical, I believe you could apply the same pages to multiple different species. Chimpanzees for example have DNA that’s 96% similar to our own. So like you said, all we’d have to do is find the remaining 4% of DNA base pairs to sequence all of the chimps that have existed.

    #30688 Reply

    Delengroth
    Participant

    Thanks! And yes indeed, it could be done for any other life form. Also remember, just like the Library contains stories that have yet to be written, so too does it contain the DNA sequences for people who haven’t been born yet.

    I actually want to applaud your thinking outside of the box. I’ve done various experiments trying to find things beyond just text and stories in the Library, but you’ve just furthered the realm of possibilities. It actually inspired me to think a little bit more on the matter, and it just dawned on me that 11.44 pages is quite small compared to how large the library is, and further, what that implies. Given that there are 4 nucleobases (A, T, G, and C), and 36,608 characters in 11.44 pages, that means (and this is just me hypothesizing), that there are 4^36,608 or 1.63 x 10^22,040 possible combinations of humans that could exist. Even if 1000 humans were born every second, the number of unique people wouldn’t run out for quite some time. That’s 163 followed by 22,038 zeroes. Consider that the universe has been around for only 4.32 x 10^17 (432,000,000,000,000,000) seconds.

    Small edit: Missed a decimal point and fixed a number

    #30700 Reply

    Ed Gore

    May I ask, what is the application of any of this hogwash? It’s an impractical thought experiment which serves no use. Dream on!

    #30713 Reply

    Delengroth
    Participant

    The applications would be limited in current times. You could, however, print out the DNA sequence of any human out into 5.58 books and store them. In the future, it may be possible for scientists to then make a clone of that human from the DNA. This would allow them to study what their ancestors were like, the same way we’ve tried to recreate Neanderthals from bones, except they’d have a live specimen.

    Side note, you can already download the genome for many organisms courtesy of NCBI:
    https://www.ncbi.nlm.nih.gov/guide/howto/dwn-genome/

    By the looks of it, I’m probably completely off with my math, and it may take more than just 5.58 books to recreate a human. As with anything else in this Library, of course it’s just a thought experiment. That’s the fun of it. Much like daydreaming about what you would do if you won the lottery.

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