Recent story about Colin Pitchfork (first person convicted of rape using DNA analysis) got me wondering how this works. How is DNA coded in a way which allows you to match it up with another sample? When you look at it under a microscope or something there aren’t exactly letters and numbers for each part of it.
In: Biology
In addition to the more old-fashioned analog method of testing the length of particular bits of the genome through gel electrophoresis, more modern methods that actually sequence the sample DNA *do* actually yield a (massive) string of letters. These letters, A, T, C and G, represent the four nucleobases (adenine, thymine, cytosine and guanine) that encode information in DNA.
The chemistry behind how a bunch of small molecules can encode huge amounts of information is something for a different post, which I’m sure has been asked and answered on this sub before. All you need to know is that similarly to how a computer can store information as a long string of zeroes and ones, DNA does something very similar but with 4 possibilities per place along the string instead. And just like you could have a computer compare two strings of binary information and calculate a % match, you can do the same with sequenced DNA.
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