Open Question
Use the following choices to answer questions 7 and 8:
a. catabolite repression
b. DNA polymerase
c. induction
d. repression
e. translatio
The mechanism by which lactose controls the lac operon.
15. Central Dogma & Gene Regulation
The Lac Operon
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In the lac operon, which of the following functions does the lactose molecule serve:
A
It is the corepressor molecule.
B
It is the repressor molecule.
C
It is the inducer molecule.
D
It serves no function in regulating the lac operon.
Verified step by step guidance1
Understand the role of the lac operon in E. coli: The lac operon is a set of genes responsible for the metabolism of lactose in E. coli. It includes genes that code for proteins needed to transport and break down lactose into glucose and galactose.
Identify the components of the lac operon: The lac operon consists of three structural genes (lacZ, lacY, and lacA), a promoter, an operator, and a repressor protein. The repressor protein binds to the operator to prevent transcription when lactose is not present.
Define the role of lactose in the lac operon: Lactose acts as an inducer molecule. When lactose is present, it binds to the repressor protein, causing a conformational change that prevents the repressor from binding to the operator.
Explain the effect of lactose binding: When lactose binds to the repressor, the repressor is unable to bind to the operator. This allows RNA polymerase to access the promoter and initiate transcription of the lac operon genes, leading to the production of enzymes that metabolize lactose.
Conclude the function of lactose: By binding to the repressor and preventing it from inhibiting transcription, lactose effectively induces the expression of the lac operon genes, facilitating the breakdown of lactose when it is available.
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