Quiz 3 Flashcards
When arginine is added to a culture growing exponentially in a medium without arginine, what occurs?
Growth continues but the production of enzymes required for the synthesis of arginine ceases.
In negative control of transcription, how does the presence of an inducer affect transcription?
The inducer prevents the repressor from binding to the operator.
Describe cAMP’s role in the lac operon.
cAMP is a regulatory nucleotide, it binds to CRP (cAMP regulatory protein). Binding of cAMP-CRP complex to DNA allows for the binding of RNA polymerase to the promotor, and transcription begins.
*When glucose is not present, cAMP accumulates.
Define microbial death
The permanant loss of reproductive ability.
Describe the two main effects antimicrobials have on microbes. How do they kill or inhibit the growth of microbes, specifically?
Alteration of the cell wall, this affects transport and makes the cell susceptible to osmotic pressure. Interferance of nucleic acids and protein structure causes a loss of function.
Describe CRP’s role in the lac operon.
CRP is an activator protein, it binds at the activator-binding site upstream from the promotor. It is used for positive regulation. cAMP is the inducer that binds to CRP, then they bind to DNA allowing RNA pol to bind and transcription of the lac operon to begin.
When more than one operon is under the control of a single regulatory protein, these operons are collectively called a(n) __________.
regulon
Certain proteins, known as regulatory proteins:
Are influenced by small molecules, regulate transcription, and bind to specific DNA sites.
Enzyme induction occurs:
When the substrate is present.
