Final answer:
Mutations on the lacZ, lacY, or lacA genes on the lac operon can prevent negative regulation of lac operon transcription.
Step-by-step explanation:
When there is a mutation on the genes lacZ, lacY, or lacA on the lac operon, it can prevent negative regulation of lac operon transcription. These genes code for proteins involved in lactose metabolism. If there is a mutation on any of these genes, it can affect the production of these proteins, potentially leading to the disruption of the negative regulation of lac operon transcription.