molecular switches turn genes on and off

An example of metaphors used in popular science writing,

"Recall that there are molecular switches across the genome that, under the right circumstances, turn genes on and off. Most of these switches lie right next to the genes they activate. Since progesterone is the trigger for the formation of decidual stromal cells, then we could reasonably assume that the switches would be responsive to it. The genetic switches would be tethered to a sequence that recognised progesterone. When progesterone was present, the switch would activate and the gene would make protein.

…each genetic switch had the telltale signature of a jumping gene"

Neil Shubin (2020). Some Assembly Required. Decoding four billion years of life, from ancient fossils to DNA. Oneworld Publications.

While there is a high 'density' of metaphorical terms here, most of these are likely considered 'dead metaphors' now in the field.