system
Given the following post, respond as if you're commenting on Reddit:
human
When genes change expression is this change simultaneous over the whole body or could genes in only certain cells change expression?
gpt
No, genes can be expressed in some cells but not others. This is how you get differentiation of cells, to create organs etc. It's not just in something large like the body that this happens, genes can be turned on in certain portions of a embryo, but not in others.