Chapter 15Gene Regulation in Prokaryotes17-1
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Sectionsto study15.1Theelements of prokaryotic gene expression15.2Regulation of transcription initiation viaDNA-bindingproteins15.3RNA-mediated mechanisms of gene regulation15.4 Discovering and manipulating bacterial gene regulatorymechanisms17-2
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 17-2 Sections to study Sections to study 15.1 The elements of prokaryotic gene expression 15.1 The elements of prokaryotic gene expression 15.2 Regulation of transcription initiation via 15.2 Regulation of transcription initiation via DNA-binding proteins binding proteins 15.3 RNA 15.3 RNA-mediated mechanisms of gene regulation mediated mechanisms of gene regulation 15.4 Discovering and manipulating bacterial gene regulatory mechanisms
Bacteria respond to environmental changes bychanginggene expressionVibrio cholerae causes choleraAquaticreservoirsOral ingestionofDiarrheacontaminated waterColonizationandorfoodMultiplicationSmall intestine17-3
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 17-3 Bacteria respond to environmental changes by Bacteria respond to environmental changes by changing gene expression changing gene expression Vibrio cholerae causes cholera
15.1Theelements ofprokaryoticgeneexpressionRNA polymeraseand thethreephases oftranscriptionInitiation-sigma subunit+core enzymeBindstopromoter,unwindsDNA,begins polymerization of basesElongation-core enzyme moves away from promoter,sigma subunitreleased,polymerization ofribonucleotides.InitiationElongationRNApolymeraseBa.Sigmaβ'asubunitBmRNAounitleavesB'DNAunwindsmPromoterPromoterTranscriptionstart site
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 17-4 15.1 The elements of prokaryotic gene expression 15.1 The elements of prokaryotic gene expression RNA polymerase RNA polymerase and the three phases of and the three phases of transcription transcription. Initiation Initiation – sigma subunit + core enzyme sigma subunit + core enzyme Binds to promoter, unwinds DNA, begins polymerization of bases Binds to promoter, unwinds DNA, begins polymerization of bases Elongation Elongation – core enzyme moves away from promoter, sigma subunit core enzyme moves away from promoter, sigma subunit released, polymerization of released, polymerization of ribonucleotides ribonucleotides
TerminationRho-dependent termination-Rho factor recognizes sequence inmRNA,binds to it, and pulls it away from RNA polymerase.Rho-independent termination-stem-loop structure formed bysequence of 20 bases with a run of 6 or more U's signals release ofRNA polymerase.TerminationTerminationorRho-dependentRho-independentStem-loop5mRNAmRNAstructuremRNApulledsignalsawayfromRNArelease ofpolymerasemRNARhofactor17-5
Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 17-5 Termination Termination Rho-dependent termination dependent termination – Rho factor recognizes sequence in Rho factor recognizes sequence in mRNA, binds to it, and pulls it away from RNA polymerase. mRNA, binds to it, and pulls it away from RNA polymerase. Rho-independent termination independent termination – stem-loop structure formed by loop structure formed by sequence of 20 bases with a run of 6 or more U sequence of 20 bases with a run of 6 or more U’s signals release of s signals release of RNA polymerase. RNA polymerase