[Campbell Biology P.419] According to the 'WHAT IF?' scenario in Concept Check 18.1, if a mu... | Practice Question

According to the 'WHAT IF?' scenario in Concept Check 18.1, if a mutation in E. coli changes the lac operator so that the active repressor cannot bind, how would this affect the cell's production of "beta-galactosidase"?

  • A: The production of "beta-galactosidase" would decrease because the lac operon would remain repressed.
  • B: The production of "beta-galactosidase" would increase because the lac operon would be constitutively expressed.
  • C: The production of "beta-galactosidase" would remain unchanged as glucose levels are the primary regulator.
  • D: The production of "beta-galactosidase" would become entirely dependent on the presence of the trp corepressor.

Explanation

The lac operon is an inducible operon normally repressed by an active repressor binding to the operator. If the repressor cannot bind due to a mutation, the operon will be continuously transcribed constitutively expressed , leading to an increase in the production of the enzymes it codes for, including "beta-galactosidase".