Gene expression is the process by which the information encoded in a gene is used to either make RNA molecules that code for proteins or to make non-coding RNA molecules that serve other functions. Gene expression acts as an “on/off switch” to control when and where RNA molecules and proteins are made and as a “volume control” to determine how much of those products are made. The process of gene expression is carefully regulated, changing substantially under different conditions. The RNA and protein products of many genes serve to regulate the expression of other genes.
Gene expression. Although an organism may have many thousand of genes encoded in the DNA, not all of those genes are actively turned on to create messenger RNA at all times. Gene expression is that process of turning on a specific gene to start making messenger RNA. The messenger RNA can then perform intended jobs in the cell, such as forming proteins. Gene expression controls both whether or not the messenger RNA is made, as well as how much messenger RNA is made at that time. We expect there to be differences in gene expression across different types of cells in the body at different stages of development and under different biological conditions, depending on the functions needed by the body at a particular time.