ABSTRACT
For a bacterium to function it is not necessary that all of its genes are transcribed at all times. To conserve energy and resources bacteria regulate the activity of their genes so that only those gene products necessary for the cell’s functions are produced. For example, it would be wasteful for a bacterium to produce enzymes required to synthesize an amino acid that was already available to it from its environment. Regulation of gene expression allows bacteria to respond to changes in their environment, typically to the presence or absence of nutrients.
