If I understand correctly, DNA determines which proteins are replicated within a cell, and therefore determine it’s function. So, it’s not as though DNA “knows” every cell in your body and builds out from a blueprint, rather your cells use DNA as instructions for how to respond to chemical stimuli.
This makes sense when talking on a small scale, like something in the environment triggering production of a specific enzyme. But what determines the creation and shape of complex organs or structures like eyes or fingers? What do those “instructions” look like? (“Keep building finger cells until blood circulation is low, then we have to start building fingernails”)?
In: Biology
It’s a good question. The general term for all the stuff that tells cells what to do beyond the DNA is “epigenetics.” It’s super complex and there’s definitely a lot of stuff that’s still not fully understood.
However, the rough idea of how it happens is that every cell has all the different sets of possible instructions for being a heart cell, a bone cell, etc. Each cells “decides” what to turn into based on signals from the other cells around it: hormones, physical contact, etc. Almost like how chat gpt finishes sentences.
Sometimes tumors have hair and teeth and stuff when these signals get messed up.
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