In a positively controlled inducible operon, the regulatory protein is synthesized as a(n) Sigma factor that can be used in eukaryotes.
Inactive repressor.
Inactive activator.
Active activator.
In wild-type E. coli, in the absence of lactose and glucose, the lactose operon will degrade its RNA polymerase so it can bind to the promoter of the operon.
Be actively producing lactose.
Fail to have the CAP protein bind to its promoter.
Have a repressor bound to its operator.
You find a strain of E. coli with a mutant CAP protein that prevents it from recognizing cAMP. What effect would this mutation have on the expression of beta-galactosidase?
Only low levels of lac operon transcription will occur.
It would convert the lac operon to repressible expression instead of inducible.
You create a partial diploid strain of E. Coli: lacl- lacZ+ lacY- (chromosome)/ lacl+ Oc lacZ- lacY+ (plasmid). Under what conditions will this strain produce high levels of permease?
Only when lactose is present without glucose.
Never.
Always.
Plasmid vectors used in cloning often contain a selectable marker (typically antibiotic resistance gene, such as Ampicillin resistance gene). What is the purpose of including this gene in the vector?
It enables the plasmid vector to replicate in E. coli host cells.
It cleaves the insert to allow it to be ligated into the vector.
It allows you to select E. coli host cells that contain the plasmid.