Switching genes on and off, what’s that all about?
Gene regulation is important for more reasons than I can count. Genes do everything by creating that “everything”.
Gene regulation is important for development. We require various cells, and various productions of RNAs and proteins, when growing from a zygote (the stage of a fertilized egg) to being an adult. Some aging signs are due to gene regulation.
It’s also important for recycling and replacement. Cells frequently have a limited “shelf life”, after which they start to recycle themselves (a process called “apoptosis”). Whether during development, or for replacement and recycling while an adult, cells need to understand when a replacement cell is required, so they can copy themselves and divide.
Another reason is all the different types of tissues in your body. They all have the same genome, however. So, what makes them differ from each other? Gene regulation. So liver genes are switched on in the liver and switched off in the lungs. The policy that makes one kind of cell act differently than another kind of cell is called Differentiation. Stem Cells are an exception and they can differentiate and end up being different separated cells.
Another point is how much RNA and protein you require. The quantity differs, but it’s never too little, nor too much. There are a host of feedback systems in the body so that when you get a bit too much of a certain protein for example, the gene producing it reduces its power, it shuts down or produces less.
Another thing that might not be too obvious are cycles. The many cycles that human bodies go through. Think of your circadian rhythm, light makes you be awake, while darkness puts you to sleep. Or think of menstruation, or getting hungry then eating then being satiated and starting all over again. Genes regulate cycles as well.
And then, for the immune system. Think of how your body creates white cells when you have an infection. Gene regulation intervenes to make the right kind of cells. However, a number of white cells are permanently switched on so your body has the knowledge to fight infections.
I’m sure I missed a few, but as you can see, plenty of good reasons why genes are turned on and off.