Positive and Negative Control. Assume you have a culture of E. coli cells growing on medium B, which contains both lactose and glucose. At time t, 33% of the cells are transferred to medium L, which contains lactose but not glucose: 33% are transferred to medium G, which contains glucose but not lactose; and the remaining cells arc left in medium B. For each of the following statements, indicate with an L if it is true of the cells transferred to medium L, with a G if it is true of the cells transferred to medium G, with a B if it is true of the cells left in medium B, and with an N if it is true of none of the cells.

a. The rate of glucose consumption per cell is approximately the same after time t as before.
b. The rate of lactose consumption is higher after time t than before.
c. The intracellular cAMP level is lower after time t than before.
d. Most of the lac operator sites have lac repressor proteins bound to them.
e. Most of the catabolite activator proteins exist as CAP-cAMP complexes.
f. Most of the lac repressor proteins exist as repressor-glucose complexes.
g. The rate of transcription of the lac operon is greater after time t than before.
h. The lac operon has both GAP and the repressor protein bound to it.