Gene switching, computer artwork. Coloured dots on a DNA helix, representing the process of switching specific genes on or off. DNA contains sections, called genes, which determine each cell’s structure, function and behaviour. How often a gene is expressed (produces functional proteins) is regulated by proteins that bind to the DNA in order to activate (switch on) or repress (switch off) the gene. Some gene therapies take advantage of this by switching certain genes on or off in order to treat a genetic disorder.