Final answer:
Having genes organized in operons offers an evolutionary advantage by allowing efficiency and coordination in gene expression. Operons enable the regulation of entire groups of genes that are functionally related, saving energy and conserving cellular space for prokaryotes.
Step-by-step explanation:
The evolutionary advantage of having genes organized in operons lies in the efficiency and coordination of gene expression. Prokaryotic structural genes are often organized into operons, which are clusters of genes under the control of a single promoter and regulatory proteins. This organization allows for a coordinated response to environmental changes, as operons can be turned on or off together, making the gene expression process more efficient. For instance, the LAC operon in E. coli consists of genes that enable the metabolism of lactose, and these genes are expressed only when lactose is present in the environment, which makes the energy use more efficient.
Operons also allow prokaryotic cells to conserve energy and regulate gene expression, since it is more energy-efficient to produce molecules only when needed, rather than having every gene expressed at all times. Furthermore, saving cellular space is another evolutionary advantage as DNA can remain more tightly coiled without the need for unwinding every gene for potential expression. Overall, the operon system ensures that gene expression is an economical process suited to the dynamic needs of the organism.