Can genes be turned on and off in cells?

Yes; each cell expresses, or turns on, only a fraction of its genes. The rest of the genes are repressed, or turned off. The process of turning genes on and off is known as gene regulation. Gene regulation makes a brain cell look and act different from a liver cell or a muscle cell. It also allows cells to react quickly to changes in their environments and is an important part of normal development. Although we know that the regulation of genes is critical for life, this complex process is not yet fully understood.

Gene regulation can occur at any point during gene expression, but most commonly occurs at the level of transcription (when the information in a gene’s DNA is transferred to mRNA). Signals from the environment or from other cells activate proteins called transcription factors. These proteins bind to regulatory regions of a gene and increase or decrease the level of transcription. By controlling the level of transcription, this process can determine the amount of protein product that is made by a gene at any given time.

For more information about gene regulation:

More information about gene regulation can be found in the NCBI Science Primer. Please refer to the sections “Gene Switching: Turning Genes On and Off,” “Controlling Transcription,” and “Controlling Translation.”

The National Institute of General Medical Science publication Genetic Basics also offers a discussion of gene regulation. Refer to the section “Controlling Genes” in Chapter 1 (How Genes Work).

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