With my basic biology knowledge I am aware that each cells characteristics are determined by the chromosomes or DNA housed in them. But if the genetic material is the only factor, how are there so many different types of cells for e.g. Red blood cells, muscle cells and neurons inspire all of them having the same chromosomes.
Is there any sort of signalling mechanism to choose which genes should be expressed for each type of cell?
In: Biology
There are mechanisms, in short, cells can sense neighboring cells or if there is no cell next to them, e.g if the cell isn’ covered in othrr cells it will become a some kind of skin cell
Cell differentiation takes place early in human development, when the embryo first begins forming. It takes place in waves, driven by carefully choreographed gene expression within the embryo cells and a complex network of signaling pathways. Almost like a crude computer, specific gene signals generate chemical outputs that guide the development of the organism. It’s a fantastically complex process we’ve barely scratched the surface of understanding.
We start with a few basic cell types that can become any tissue in our body. As different growth phases occur, those cells are told to become specific cell types that will become the tissue that’s being developed in that phase. This continues until the organism is developed and the cells are no longer needed.
Cells decide which parts of their DNA to read and lock up the rest. This happens very early on in embryonic development, when the body is just a hollow ball of cells with three layers (and even before, but the three layered example is easiest) The cells on the outside layer will start reading the parts of the dna that will tell them how to become skin and nerves. [Article](https://biologywise.com/information-about-the3-germ-layers-in-animals) The middle layer will become muscle and bones, and the inner layer becomes the gut lining.
Now the signalling mechanisms for where in the embryo a cell is are darn complicated and have to do with neighbouring cells and extracellular signals.
But the important thing is, once a cell is differentiated, it’s very hard for it to go back and become a different cell type. Scientists work very hard to figure out how to do force un-differentiation because it could help with a lot of medical applications.
But on a more general level there is constantly a lot of signalling going on between cells that lead them to express one gene or another, and the specifics are quite tedious.
It’s by a process called epigenetics. Essentially your cells all have the instructions on how to do everything, but as cells decide what kind of cell they are, different instructions (parts of the DNA) get marked as not needed and therefor do not get expressed, essentially erasing them from the cell. So different cells differ in what genes they epigenetically silence, and which they amplify (where the cell does the opposite and decides a gene is important and makes it easier to use).
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