What type of operon is illustrated in Model 1?
An inductible operon
Consider the operon In Model 1. Other than the gene that regulates the operon, how many genes are contained within the operon?
In model one, where on the DNA strand does RNA polymerase bind to start transcription, the promoter, the operator or the terminator?
The RNA polymerase binds to the promoter.
Which direction is the RNA polymerase moving in model 1?
Left to right
From 3′ to 5′ end
From 3′ to 5′ end
In which diagram of model 1 is transcription and translation occurring successfully, diagram A or diagram B? Justify your answer with evidence from model 1.
Transcription is occurring in diagram B. That diagram shows the mRNA and proteins being made from the DNA.
Spot where transcription begins
Spot where transcription ends
What protein does the regulatory gene in model 1 produce?
A repressor protein
To what section of the operon does this protein bind?
The repressor protein binds to the operator site.
Propose an exclamation for why transcription is not occurring in diagram A.
The repressor protein blocks RNA polymerase so transcription of genes X, Y, and Z cannot occur.
When an inducer molecule attaches to the repressor protein, what happens to the repressor protein?
The repressor protein changes shape.
How does the change identified in part A allow transcription of the genes in operon to occur?
The repressor protein no longer binds to the operator and is no longer blocking RNA polymerase, so transcription can occur.
Explain what would happen within the lac operon in each of the following scenarios:
Not enough allolactose is present. The repressor protein binds to the operator, not allowing transcription of the operon genes. Without those jeans producing the correct enzymes, lactose is not metabolized
Explain what would happen with the LAC operon in each of the following scenarios: high lactose.