Regulating genes
Your body needs to make some proteins throughout your life whereas others are only needed at certain times. So all genes are regulated, allowing a cell to make the right amount of protein, just at the time when it is needed. Many proteins in the growing embryo are only needed for a very short time. The proteins made by a particular cell depend on where it is in the embryo, how old the embryo is, and the instructions it receives from its own genes and from other cells.
