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19 Cards in this Set

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Global Control Systems
Regulatory mechanisms that respond to environmental signals and effect many different genes
Catabolite repression
When other carbon sources besides the one being utilized is being repressed
Diauxic growth
The response when glucose and lactosee are both present in the me
What physiological processes are controlled by catabolite repression in E.coli?
Enzymes for lactose utilization are not induced even though lactose is present.
When E.coli is grown in medium containing both glucose and lactose, how to the levels of these sugars change during the growth of the culture? How does the growth curve compare to that of cells grown in a medium containing only one carbon source? What is this phenomenon called?
The glucose is used up first and the enzymes for lactose utilization are not induced even tho lactose is present, when glucose is gone, then lactose goes into use but at a slower level. Growth curve for one source would have the typical lag, expo, stat, death, this however has lag, expo, lag, stat, death. This phenomenon is called diauxic growth in E.Coli
What changes occur, and what are the molecular mechanisms directing these changes in gene expression, during growth in the presence of these two carbon sources?
Lac Operon- lactose repressor, binds in, needs cAMP to bind as well.
Operon
A single transcriptional unit expressed coordinately from a single promoter and regulated by a common operator
Regulon
A set of operons, whose locations vary on the chromosome, that are regulated by a common repressor or activator. Products of the operons are often related, members of the same pathway.
Modulon
Sets of operons and regulons that are bound by a common global goal, but are otherwise seeminly unrelated, are controlled by a common regulator.
Attenuation
Refers to a regulatory process where the control occurs after the initiation of transciption but before its completion. This scheme controls the number of transcipts that go to completion.
What are the two general characteristics of an operon controlled by attenuation?
1. Leader RNA alternative folding schemes

2.Rho-independant terminator structure.
Leader Protein
Has codons related to the biosynthetic pathway encoded by the operon.
What role does a32 play in the heat shock response of E.coli? How is the level of this protein regulated?
-a32 directs expression of new set of genes.

-Regulated-less stable at 37 degrees, and stabilized at higher temperatures.
alternative sigma factors
can alter the specificity of promoter recognition of the RNA polymerase holoenzyme..
How does vibro fisheri sense the density of its population?
-Quorum sensing puts out small molecules and you get bioluminscence.

-High levels of AHL molecules is when bioluminscence is given off.
How is an environmental signal transduced by a two-component regulatory systems? At what level of gene expression do they exert their effect?
-Membranes associated sensor kinase binds to stimulator molecule, the sensor kinase autophosphorylates, the phosphorylated sensortransfers its PO4 to a response regulator, the response regulator then modulates transcription.

-Transcription
What role does the mRNA play in a riboswitch regulatory scheme? How might an antisense RNA effect the level of translation?
-The mRNA binds a small molecule and blocks translation initiation.

-An anti-sense RNA molecule binds to the mRNA blocking access to the SD sequence. Anti-sense RNA are also involved in control of porteolysis and iron homeostatis in E.coli.
Two component regulators
-Are a common scheme for responding to environmental stimuli
Catabolite activator protein
Positive control factor requires cyclic AMP as co-activator