4 ms·

Not only is DNA chemically stable and can last for years, has internal redundancy, but it is remarkably compact. DNA is an evolutionarily optimal data storage m

Not only is DNA chemically stable and can last for years, has internal redundancy, but it is remarkably compact. DNA is an evolutionarily optimal data storage medium. To put it into context, each cell in your body contains 6 billion base pairs of data (two copies of your genome). Each base is one of 4 bits, so that’s 4^6000000000 of data in each cell. Your body has ~37 trillion cells [1]. A person is about the size of a rack (well, maybe 10-15U by volume), so that’s 3.7e13 * 4^6e9 bits per rack. A petabyte is 8e15 bits. That’s a lot of data storage capacity in a small space. Moreover, there is the potential for introducing more synthetic bases to increase the 4 to 6. https://www.ncbi.nlm.nih.gov/m/pubmed/23829164/ https://www.ncbi.nlm.nih.gov/m/pubmed/23829164/

dooglius 8y ago
The number of bits is the logarithm of possible cases; there are only two bits needed to describe the four bases, and only 12 billion bits needed to describe the 4^(6e9) possible configurations of data.
yread 8y ago
Moreover cell contains mostly other stuff than a nucleus so that's another factor of 10 or so. And human body has a lot of 'empty' space - lungs, stomach, veins, collagen, bones,....
hn_throwaway_99 8y ago
Minor correction: each base pair is one of 4 values (A, T, G, C), so each base pair is equivalent to 2 bits of data, which gives a number half of what you quoted.
- faissaloo 8y ago
  8 if you include artificial base pairs (P, Z, B, S)
- mbreese 8y ago
  Yes, I misworded it and gave the wrong numbers. I gave the number of possible combinations in a genome, which is 4^6e9. That’s obviously not the number to compare (and a slightly embarrassing mistake). With 6 gigabases per cell and 2bits per base, the storage capacity is 12 gigabits (1.5 gigabytes) per cell. And with 37 trillion cells (3.72e13) in a human body, that’s 3.72e13 cells * 1.5e9 bytes per cell which is 5.58e22 bytes per person or 55 zettabytes. This seems like a more reasonable number.
gpm 8y ago
Another minor correction: Each base pair is one of 4 things, so 2 bits of information. Each base is half of a base pair so can really only claim 1 bit of information. Of course even when you said base you did the math with # of base pairs, so it doesn't really matter.
- hn_throwaway_99 8y ago
  No, that is not correct. While each base is half of a base pair, each pair is NOT reversible. At each position along one strand you have 4 options, so each base encodes 2 bits. Even though A always pairs with T and G with C, which strand each base is on matters, so in other words if you have pair "A-T" followed by "G-C" that is very different from "T-A" followed by "C-G".
  - gpm 8y ago
    You have a problem with your counting. Each location can be in one of four possible states: T-A A-T G-C C-G That location, using 2 base's, encodes 4 possible values, i.e. 2 bits. I.e. 1 bit per base.
modzu 8y ago
so in the matrix we'll really be hard drives, not batteries
- jonplackett 8y ago
  Favourite comment in a long time
- dluan 8y ago
  Kind of like bags of bitcoin really.

dooglius 8y ago

The number of bits is the logarithm of possible cases; there are only two bits needed to describe the four bases, and only 12 billion bits needed to describe the 4^(6e9) possible configurations of data.

yread 8y ago

Moreover cell contains mostly other stuff than a nucleus so that's another factor of 10 or so. And human body has a lot of 'empty' space - lungs, stomach, veins, collagen, bones,....

hn_throwaway_99 8y ago

Minor correction: each base pair is one of 4 values (A, T, G, C), so each base pair is equivalent to 2 bits of data, which gives a number half of what you quoted.

faissaloo 8y ago
8 if you include artificial base pairs (P, Z, B, S)
mbreese 8y ago
Yes, I misworded it and gave the wrong numbers. I gave the number of possible combinations in a genome, which is 4^6e9. That’s obviously not the number to compare (and a slightly embarrassing mistake). With 6 gigabases per cell and 2bits per base, the storage capacity is 12 gigabits (1.5 gigabytes) per cell. And with 37 trillion cells (3.72e13) in a human body, that’s 3.72e13 cells * 1.5e9 bytes per cell which is 5.58e22 bytes per person or 55 zettabytes. This seems like a more reasonable number.

gpm 8y ago

Another minor correction: Each base pair is one of 4 things, so 2 bits of information. Each base is half of a base pair so can really only claim 1 bit of information. Of course even when you said base you did the math with # of base pairs, so it doesn't really matter.

hn_throwaway_99 8y ago
No, that is not correct. While each base is half of a base pair, each pair is NOT reversible. At each position along one strand you have 4 options, so each base encodes 2 bits. Even though A always pairs with T and G with C, which strand each base is on matters, so in other words if you have pair "A-T" followed by "G-C" that is very different from "T-A" followed by "C-G".
- gpm 8y ago
  You have a problem with your counting. Each location can be in one of four possible states: T-A A-T G-C C-G That location, using 2 base's, encodes 4 possible values, i.e. 2 bits. I.e. 1 bit per base.

modzu 8y ago

so in the matrix we'll really be hard drives, not batteries

jonplackett 8y ago
Favourite comment in a long time
dluan 8y ago
Kind of like bags of bitcoin really.