Post on 18-Dec-2015
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Why Regulate Gene Expression?Response to changing developmental or environmental conditionsSave…timeenergyraw materials
Prokaryotic RegulationFeedback Inhibition Product inhibits
enzyme function
Regulation of transcription Product inhibits
enzyme production
Drug CompanyDrug CompanyResearch andDevelopment
Research andDevelopment DistributionDistributionTestingTesting ProductionProduction
MGMTMGMT
Operon RegulationInducible
Default off Repressor active
Turned on when substrate is present
Repressor inactive
Repressible
Default on Repressor inactive
Turned off when product is present
Repressor active
Inducible OperonDefault: OFF
1 2 3P ORGRNAPoly
Substrate AbsentRepressor protein binds to operatorOperon blockedNo substrate-catabolizing enzymes produced
Substrate PresentSubstrate inactivates repressor proteinOperon transcribedEnzymes produced
Repressible OperonDefault: ON
1 2 3P ORGRNAPoly
Product AbsentRepressor protein inactiveOperon transcribedProduct-anabolizing enzymes produced
Product PresentProduct activates repressor proteinOperon blockedNo enzymes produced
Inducible, Repressible, Both, or Neither?1. The Lac operon2. Regulatory gene codes for repressor protein3. Operon expressed (ON) by default4. Substrate inactivates repressor protein5. Product binds to RNA polymerase6. Product activates repressor protein7. Repressor protein status changes when bound by particles8. Enzymes deactivate repressor protein9. The Trp operon10. Operon blocked (OFF) by default11. Active repressor protein blocks transcription12. Repressor is created in an active state
Inducible, Repressible, Both, or Neither?1. The Lac operon I2. Regulatory gene codes for repressor protein B3. Operon expressed (ON) by default R4. Substrate inactivates repressor protein I5. Product binds to RNA polymerase N6. Product activates repressor protein R7. Repressor protein status changes when bound by particles B8. Enzymes deactivate repressor protein N9. The Trp operon R10. Operon blocked (OFF) by default I11. Active repressor protein blocks transcription B12. Repressor is created in an active state I
Tend to have 10x the genes of prokaryotesExpression is controlled at multiple points
EukaryoticRegulation
Chromatin ModificationMethylation
Attachment of methyl groups to cytosine
Histone Acetylation Attachment of acetyl groups to histones Loosens grip of histones on DNA