Gene regulation is important for all cells to be able to control gene repression and the amount of proteins produced by those genes. It helps to make sure the cell uses resources efficiently and express the right genes under the right conditions. Gene regulation can be found in both prokaryotic and eukaryotic cells. The methods of regulation differ between the two groups.
Prokaryotic regulation mostly occurs by enzymes interacting with DNA and the gene of interest. There are enzymes produced for that function at all times called constituent enzymes. There are also enzymes are only made during certain biological conditions these are adaptive and are called inducible enzymes. These enzymes in gene regulation can exhibit either positive or negative control. Positive control allows transcription to occur only when a regulatory enzyme stimulates RNA production. Negative control means genes will be transcribed until a regulatory enzymes blocks or interferes with transcription. One example of gene regulation of prokaryotes is the lac operon gene. Cells have a mechanism to ensure that only certain enzymes are present when a certain resource is available. When glucose is present the cell has certain enzymes to help in glycolysis. When glucose is absent and lactose is present the cell needs specific enzymes to deal with lactose. Gene regulation makes sure that lactose genes and enzymes aren’t being produced if lactose is absent and there is no need for the enzymes. (Klug, 2012)
The lactose enzymes are all located together on a gene. The regulatory regions of the gene are located upstream; it includes the promoter and operator regions. The structural genes or genes that encode for enzymes are located downstream the promoter and operator. Part of the gene (lacI) encodes a repressor molecule which creates chemical and physical changes when binds to other molecules. When the repressor molecule is bound to