Final answer:
The transcription of the lac operon indeed results in a single polycistronic mRNA that includes lacZ, lacY, and lacA genes; hence the answer is true. A mutation in one of these genes could disrupt lactose metabolism in E. coli.
Step-by-step explanation:
The statement that transcription of the lac operon produces a single polycistronic mRNA containing the lacZ, lacY, and lacA genes is true. The lac operon consists of regulatory regions such as the promoter as well as the structural genes lacZ, lacY, and lacA, which code for proteins involved in lactose metabolism.
These genes are co-transcribed into a single mRNA when lactose is present and acts as an inducer. A mutation in one of the structural genes of the lac operon would lead to the production of a defective protein. Depending on the function of this protein within the lac operon pathway, this mutation could affect the E. coli's ability to metabolize lactose.