How does your DNA know where it is in your body and which body part to grow into?
In: Biology
Some parts of your DNA are regulatory genes. They don’t build anything used for tissue or enzymes or anything like that. Instead, they build proteins that activate other parts of your DNA. So, say your DNA is trying to build an eyeball. It doesn’t immediately start making an eyeball. Instead, there’s a gene for “build an eyeball” and that gene turns on another gene that says, “build a retina” and *that* gene turns on *another* gene that says, “build a nerve cell” and so on.
Those regulatory genes are activated by any number of chemical signalers. Some of them turn themselves on and off. So for instance, to build fingers there is a signal that both turns on the “build a finger” gene *and* turns *off* the genes that build itself. So the more of this signal there is, the less of it will be made. So you end up with pockets of high levels of this signal, but they fall off really quickly. So your body builds a finger where those signals are strong, but not where none exist.
Similar signals pervade your body. Signals turn genes on or off which turn on or off other signals, which turn on or off the genes that code for the actual “stuff” that you’re made out of. Every type of cell tells every other cell what kind it is, and affects which parts of their DNA is activated, which feed back to that first cell and tells *it* what DNA to activate. Before your cells even start to differentiate, when you’re just an embryo barely starting to form, the cells still started with some signals that affect the growth of the cells from that point forward so they *do* begin to differentiate.
Latest Answers