You are studying a bacterium that utilizes a sugar called athelose. This sugar can be used as an energy source when necessary. Metabolism of athelose is controlled by the ath operon. The genes of the ath operon code for the enzymes necessary to use athelose as an energy source. You have found the following: The genes of the ath operon are expressed only when the concentration of athelose in the bacterium is high. When glucose is absent, the bacterium needs to metabolize athelose as an energy source as much as possible. The same catabolite activator protein (CAP) involved with the lac operon interacts with the ath operon. Based on this information, how is the ath operon most likely controlled?

The ath operon is most likely controlled by the CAP and a repressor similar to the lac operon.        

Explanation:

The CAP senses the low concentration of glucose and activates the transcription of the ath operon for it to metabolize the athelose and obtain energy. When the glucose is in high concentrations, the ath repressor, which works as a  lac repressor, inhibits the transcription of the ath operon, it does this by binding to a part of the operon called operator getting in the ARN polymerase way and stoping the transcription. If there is glucose, the repressor binds to it and it is not bound to the operon allowing the transcription and metabolism of glucose.                                  

The control of an ATH OPERON has both negative and positive sides,they are as follows;

POSITIVE CONTROL OF AN ATH OPERON IS BY;

- Inactive activator ( not glowing w/o yellow square)

- Catabolite activator protein (cAMP)

- Active activator ( glowing w/ yellow square)

NEGATIVE CONTROL OF AN ATH OPERON IS BY;

- Active repressor( glowing w/o yellow square)

- athelose

- Inactive repressor ( not glowing w/ yellow square)

Explanation: The OPERON MODEL describes how bacteria controls the production of groups of enzymes.In operon model, synthesis of the RNA messenger coding for these enzymes is switched on or off by regulatory proteins.

Regulatory proteins bind to the operator to control expression of the operon while a repressor is a protein that inhibits gene transcription,in prokaryotes this protein binds to the DNA in or near the promoter.