Can genes be turned on and off in cells?
Gene regulation is the critical process by which cells control which genes are active, allowing them to perform specialized functions and respond to environmental changes.
Overview
Each cell expresses, or turns on, only a fraction of its genes at any given time. The rest of the genes are repressed, or turned off. The process of turning genes on and off is known as gene regulation. This is an important part of normal development; genes are turned on and off in different patterns to make a brain cell look and act differently from a liver cell or a muscle cell. Gene regulation also allows cells to react quickly to changes in their environments. Although this process is critical for life, it is not yet fully understood.
The Mechanism of Gene Regulation
Gene regulation can occur at any point during gene expression, but it most commonly occurs at the level of transcription, when the information in a gene’s DNA is passed to mRNA. The process functions as follows:
- Signals from the environment or from other cells activate proteins called transcription factors.
- These proteins bind to regulatory regions of a gene.
- Binding increases or decreases the level of transcription.
- By controlling the level of transcription, the cell determines when and how much protein product is made by a gene.