regular_modern_girl t1_ishp1le wrote on October 16, 2022 at 1:49 AM

Reply to comment by halfhalfnhalf in When it's said 99.9% of human DNA is the same in all humans, is this referring to only coding DNA or both coding and non-coding DNA combined? by PeanutSalsa

yeah genes are just sequences of codons which each correspond to an amino acid subunit of a protein, certain amino acids have to be in just the right places in a protein’s structure for it to not end up as a useless squiggly mess (useless at best, potentially toxic at worst, just look at the formation of amyloid plaques), and if even one base pair is off in DNA, that changes a given codon to another one (meaning there will be the wrong amino acid, and the whole protein is probably ruined).

I do 3D printing, and kind of think protein synthesis and folding as similar in a certain way; when you’re 3D printing something (on a FDM printer, at least), all it takes is one little crossing of one layer being set down wrong, and before you know it, you have an unrecognizable mass of plastic spaghetti that doesn’t resemble what you were originally trying to print in the slightest, and you have no choice but to toss the whole thing in the recycle bin and start over. The problem is, with misfolded proteins there sometimes isn’t any “starting over” if they’re essential enough to a cell, and there often isn’t an analogue to a recycle bin either (so some misfolded proteins can just keep accumulating until there’s severe disease).

Basically, in both cases all it takes is one small error, and an entire print/protein ceases to be functional.

This is why mutations that lead to disease are generally more common than ones which end up being beneficial (as for an organism to benefit, it basically takes the altered protein actually being better than the original, or good for something else).

Splatulance t1_isiapmr wrote on October 16, 2022 at 5:00 AM

Some dna isn't transcribed but has a significant impact on transcription/expression. Transcription is like the publicly exposed API

regular_modern_girl t1_islczzm wrote on October 16, 2022 at 9:04 PM

Yeah I was kind of thinking how errors in promoters could be thought of like issues in the g-code (the programming language that 3D printers, laser cutters, etc. use) leading to certain layers not being printed and stuff like that.

Of course one aspect where this metaphor really breaks down is the time it takes to 3D print something versus a protein to fold into shape; the former takes anywhere from minutes to hours (depending on the size of the print, resolution, etc.), whereas the latter somehow occurs in just fractions of a second (and the mechanics of exactly how it happens so fast is still not entirely clear, which is why we still don’t really have accurate computer models of protein folding, and the field of protein engineering is still fairly nascent. Once we do have a better understanding, synthetic biology will enter a new age in which it will become not only possible to use tools like CRISPR Cas9 to edit genomes by inserting or removing pre-existing genes like we do now, but actually build entirely new genes from scratch, for novel proteins that have never existed in nature. We’ll basically have the most powerful pre-existing system for nano-engineering right at our fingertips).