Final answer:
Repressor proteins bind to operator regions and physically block gene transcription, while activator proteins bind to enhancer regions and enhance gene transcription.
Step-by-step explanation:
Repressor and activator proteins are involved in regulating gene expression by binding to specific regions of DNA. Repressor proteins bind to operator regions, which are located between the RNA polymerase binding site of the promoter and the transcriptional start site of the first structural gene. By binding to the operator, repressor proteins physically block the transcription of a gene. On the other hand, activator proteins bind to enhancer regions. These enhancer regions can be located thousands of nucleotides away from the gene they regulate. Activator proteins enhance the interaction between RNA polymerase and a particular promoter, facilitating the transcription of the gene.