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Control of Gene Expression in Bacteria
N/A
55
Biology
Undergraduate 1
03/25/2012

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Cards

Term
 
 
specific singals from environ affect?
Definition

 

 

trigger gene expression

Term

 

 

3 steps gene expression can be controlled at

Definition

 

 

transcription

translation

post translational modification

Term

 

 

Stopping before mRNA is made

 

(stopping during transcription)

Definition

 

 

if no mRNA then ribosomes cant mek genetic product

transcription control

Term

 

 

transcription control

Definition

 

 

occurs when regulatory proteins affect RNA poly's abilitiy to bind to a promoter and initiate trancription

 

DNA--/-->mRNA

Term

 

 

Translational control

Definition

occurs when regulatory moelcules alter the lenght of time an mRNA survives before its degraded by ribonucleases

OR

affect translation initianton

OR

elongation

Term

 

 

post translational control

Definition

 

 

some proteins are manufactured in an active forma and have to be activated by chemical modification

(phosphorylation)

 

opp=dephosphoylation

Term

 

 

Pros for transcriptional control

Definition

 

 

saves most energy for cells if stop at earliest point

 

Term

 

 

Pros for translational control

Definition

 

 

allows a cell to make rapid changes in relative amnts of different proteins

Term

 

 

pros for post tranlation control

Definition

 

 

provides most rapid response

Term

 

 

constitutively

Definition

 

 

always occuring

always present

Term

 

 

glycolysis

Definition

 

 

begins w/glucose

main pathway for the production of ATP

(lactose is also used  but ONLY when glucose depleted)

Term

 

 

β- glactosidease

Definition

 

 

catalyzes the rsn that breaks lactose down into glucose and galactose

Term

 

 

Glyolytic pathway

Definition

 

 

glucose that is released in glycolysis goes into this pathway

Term

 

 

inducer

Definition

 

substrate in a rxn that stimulateds the expression of a specific gene

 

(lactose)

Term

 

 

how to produce much β- glactosidease

Definition

 

 

lactose very high

 

(No glucose is present)

Term

 

 

genes that cant use lactose lack..

Definition

 

lackeither

β- glactosidease

OR

lactose transporter protein

Term

 

 

mutagens

Definition

 

 

chemicals that damage DNA and INC mutation rate

Term

 

 

medium

Definition

 

 

a liquid or solid that supports growth

Term

 

 

replica plate

Definition

 

 

cells from the velvet stick to the plates surface, producing an exact copy of the lcoation of the colonies on the master plate

Term

 

 

Indicator plates

Definition

 

 

where mutants with metabolic deficiences are observed directly

Term

 

 

Cells that cannot cleave indictor molecule even if galactose is present as an induceer

means?

Definition

 

no β- glactosidease

gene for β- glactosidease is defective

(lacZ defective)

Term

 

 

cells the cannot accumulate lactose must mean?

Definition

 

 

no membrane protein (glactoside permease) to import lactose

- gene for galactoside permease is defective (lac Y)

Term

 

 

cells cleave indicator molecules even if lactose is absent as an inducer means?

Definition

 

consitutitve expression of lacZ and lacY 

gene for regulatory protein that shuts down lacZ and lac Y is defective(lacI)

Term

 

 

Lac Z

Definition

 

 

gene for β- glactosidease

Term

 

 

lacY

Definition

 

 

gene for galactoside permease

Term

 

 

lacI

Definition

 

 

gene for regulatory protein that shuts down lacZ and lacY when lactose is absent

Term

 

 

negative control

Definition

 

 

occurs when a regulatory protein binds to DNA and shuts down transcription

Term

 

 

positive control

Definition

 

 

occurs wehn a reg protein binds to DNA and triggers transcription

Term

 

 

represson

Definition

 

 

inhibitor that exerts neg control

 

(lac I produces on that exerts neg control on lacZ and lacY)

Term

 

 

Repressor present, lactose absent....

Definition

 

repressor binds to DNA

 

transcription is blocked

 

(lac I synthesized repressor)

Term

 

 

Repressor Present, lactos present...

Definition

 

 

lactose (inducer) binds to repressor

repressor released from DNA

transcription occurs

Term

 

 

No repressor , lactose present...

Definition

 

 

transcription occurs

Term

 

 

Operon

Definition

 

 

a set of coordinately regulated bacterial genes that are transcribed together into one mRNA

Term

 

 

lac A

Definition

 

 

found to be tightly linked with laxZ and lac Y

-codes for enzyme transacetylase

Term

 

 

transacetylase

Definition

 

 

-protective

-catalyzes certain types of sugars to be exported when they are too abundance

-coded by lacA

Term

 

 

allosteric regulation

Definition

 

 

-small molecule binds directly to a protein and causes it to change its shape and activity

 

(inducer-lactose-binds to repressor neg control ends; transcripiton can proceed)

Term

 

 

importance about lac operon model

Definition

 

 

gene expression is regulated by physical contact btwn regulatory proteins and specific regulatory sites in DNA

Term

 

 

catobolite repression

Definition

 positive transcriptional control

end product of a catabolic pathway inhibits further transcription of the gene encoding an enzyme early in the pathway

 

(ex-hydrolysis of lactos into subunits by β- glactosidease)

Term

 

 

catabolite in the catabolic repression of lac operon

Definition

 

 

glucose

-when abundant in cell transcriptiono f lac operon is decreased

Term

 

 

HIGH glucose ouside the cell

inside.......

Definition

inactive adenylyl cyclase

 

LOW cAMP

 

CAP does NOT bind to DNA

 

= infrequent transcritpion

Term

 

 

LOW glucose outside the cell

inside cell....

Definition

active adenylyl cyclase

 

HIGH cAMP

 

CAP-cAMP complex binds to DNA

 

=frequent transcription

Term

 

 

catabolite activator protein

(CAP)

Definition

 

(+) control of lac operon depends on theis regulatory protein

Term

 

 

CAP binding site

Definition

 

 

lcoated just upstream of lac operon

Term

 

 

strong promoters...

Definition

 

 

allow efficient initiation of transcription by RNA polymerase

Term

 

 

weak promoters

Definition

 

 

support much less efficient initiation of transcription

Term

 

 

lac promoter is weak 

how is that fixed?

Definition

 

 

CAP reg protein is bound to CAP site the protein interacts w/RNA poly and allows transcription ot begin much more frequently

Term

 

 

cyclic AMP

(cAMP)

Definition

 

 

CAP cant bind to the CAP binding site unless this reg molecule binds to it

Term

 

 

When cAMP present....

Definition

 

 

-cAMP-CAP complex forms and binds to DNA at the CAP site

-RNA poly binds to promoter EFFICIENTLY

 

*transcription=frequent

Term

 

 

When cAMP is absent....

Definition

 

 

-CAP does not bind to DNA

-RNA poly binds to promoter inefficiently

 

*transcription = infrequent

Term

 

 

adenylyl cyclase

Definition

 

 

produced cAMP from ATP

-its activity inhibitied by glucose

Term

 

 

HIGH glucose LOW cAMP

 

Lactose Low (repressor binds to DNA)

Definition

 

 

Infrequent Transcription

Term
 
HIGH glucose Low cAMP
 
HIGH lactose (repressor removed)
Definition

 

 

infrequent transcription

Term

 

 

LOW glucose HIGH cAMP

 

HIGH lactose (repressor removed)

Definition

 

 

frequent transcription

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