E. coli possesses a number of genes coding for a variety of enzymes that enable the cell to take up and metabolize any of several different sugars. Which enzymes are actually made is determined by which sugars are available in the environment. This way, the bacterium doesn't waste energy making enzymes that don't have any available substrate. B. Gene regulation in eukaryotes. With eukaryotes there is a greater degree of complexity with respect to both the signals that influence gene expression and the impact that gene regulation has on the organism.
Eukaryotic cells respond to a greater range of regulatory stimuli .
As with E. coli , eukaryotic cells respond to changes in the environment by altering the expression of genes. For example, plant cells switch on the genes for photosynthetic proteins in response to light. In a similar manner, hormones, growth factors and other regulatory molecules are produced by one type of cell and cause changes in gene expression in other cells. In this way the activities of groups of cells can be coordinated in a manner that is beneficial to the organism as whole. Some eukaryotic genes are developmentally regulated .