In the bacterium Bacillus subtilus, there are fivegenes coding for proline biosynthetic enzymes. They are locatedadjacent to one another on the chromosome. If excess proline ispresent in the medium, the synthesis of all five enzymes iscoordinately repressed, whereas in the absence of proline, all fivegenes are coordinately expressed.
a. Most mutations in this region of the chromosome result in theloss of activity of only one of the enzymes. Explain how such amutation would only effect the production of one enzyme. What isthe counterpart of this type of mutation in the lac operonsystem?
b. Some mutations, mapping to one end of the cluster of prolinebiosynthesis genes, result in the loss of all five enzymes, eventhough none of the structural genes have been lost. Explain howsuch a mutation could affect all five genes. What is thecounterpart of this type of mutation in the lac operonsystem?
