This comment got me thinking how absolutely bonkers DNA replication is when you try to explain it with any sort of metaphor.
A thread.
A thread.
First, imagine that your 3GB file is cut into 23 pieces and stored on 3 feet of magnetic tape. Data redundancy is important, of course, so let's double it into 46 pieces (6ft) for good measure.
Each of the 46 pieces of tape is actually two identical but complementary pieces, encoding the same data, but glued together in opposing orientation.
Each piece is twisted up like a rotini noodle, wrapped around a few million tiny marbles for organization, then twisted again, over and over until it's a rat's nest of data that can fit into the period of this sentence.
We toss that tangle of tape into a vicious environment where little gnomes with garden shears are constantly trying to cut it apart and insert the gnomAD Mixtape Vol. 2, UV radiation melts it, and the sysadmin is a chain smoker.
Now we need to copy this hairball of information, and the only way to do so is to clamp on a little roomba running a Ctrl+C/Ctrl+V script.
Before this copy-roomba can do anything, it needs to recruit a Toy Story-esque pantheon of misfit toys to unravel the tape, unglue it from the marbles, and separate the complementary strands.
Once we untangle our tape into something roughly linear, the copy-roomba is good at its job, but will gag on any tape that has been nicked, cut, kinked, sun-damaged, or overheated.
When that happens, it will call for help from a smaller, stupider copy-roomba that will copy a bit of gibberish to get past the broken tape.
If the original copy-roomba stays stuck, the entire strand of data will be corrupted, and the system will crash. Better to make an error or two til you hit that all-important EOF signal.
Meanwhile, another version of the copy-roomba is doing the same thing, moving in the opposite direction on the piece of complementary tape.
Almost immediately after this happens, the displaced marbles need to be put back exactly as they were...did I mention that their spacing and the type of marble used is also important for data fidelity?
Now repeat this 10 quadrillion times over your lifetime. Oh, also, all the bits of data are quarternary. Oh, and the timing of each copy process has to be elaborately orchestrated to ensure the server rack doesn't explode.
And this is why (to me at least) the mutation and repair of DNA is the most fascinating topic in all of biology. If life in 2018 seems kinda shitty, remember that at the molecular level, it's still beautiful, and studying it is one hell of a fun way to spend your time.
