The
Lactose Operon in the
Presence of an Inducer
- The regulator gene
codes for an active repressor protein.
- Lactose, the inducer molecule binds
to the active repressor protein.
- The binding of the inducer alters the
shape of the repressor causing it to become inactivated.
- The
inactivated repressor protein is then unable to bind to the operator region of
the operon.
- Since the inactive
repressor protein is unable to bind to the operator region, RNA polymerase (the
enzyme responsible for the transcription of genes) is now able to bind to the
promoter region of the operon.
- RNA polymerase is now able to transcribe the
three enzyme genes (Z, Y, and A) into mRNA.
- With the transcription of these
genes, the three enzymes needed for the bacterium to utilize the sugar lactose
are now synthesized.
Copyright © Dr Gary E. Kaiser