When AraC binds to arabinose to initiate the process of transcription, then AraC is acting as an Activator.
Explanation:
Transcription is a process that help to produce messenger RNA from the DNA that is present in the nuceloids of bacteria cells. The production of these mRNA however, depends on the intracellular condition of the bacteria, for example, if there is a need for the protein coded for by the segment or not. In the case of this bacterium, the AraC can act as a repressor only when there is no arabinose sugar in the cell. In the scenario above, AraC will act as an activator because of the presence of the sugar arabinose.
