CAMPBELL BIOLOGY IN FOCUS © 2014 Pearson Education, Inc. Urry Cain Wasserman Minorsky Jackson Reece Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge 15 Regulation of Gene Expression

© 2014 Pearson Education, Inc. Figure 15.1

© 2014 Pearson Education, Inc. Figure 15.2 Regulation of gene expression Precursor trpE gene (a) Regulation of enzyme activity Feedback inhibition Enzyme 1 Enzyme 2 Enzyme 3 Tryptoph an (b) Regulation of enzyme production trpD gene trpC gene trpB gene trpA gene

© 2014 Pearson Education, Inc. Operons: The Basic Concept ▪_________________________________________ _________________________________________ ▪_________________________________________ _________________________________________ _________________________________________

© 2014 Pearson Education, Inc. ▪_________________________________________ _________________________________________

© 2014 Pearson Education, Inc. Figure 15.3 Promoter trp operon Genes of operon DNA Regulatory gene mRN A Prote in RNA polymeras e Inactive repressor Operator Start codon Stop codon mRNA 5′ trpEtrpDtrpC trpB trpA EDCBA (a) Tryptophan absent, repressor inactive, operon on DNA mRN A Prote in Activ e repre ssor No RNA mad e Tryptophan (corepressor) (b) Tryptophan present, repressor active, operon off Polypeptide subunits that make up enzymes for tryptophan synthesis 5′ 3′ trpR

© 2014 Pearson Education, Inc. Repressible and Inducible Operons: Two Types of Negative Gene Regulation ▪__________________________________________ __________________________________________ ▪__________________________________________ __________________________________________ __________________________________________

© 2014 Pearson Education, Inc. Figure 15.4 DNA mRN A Promoter Operator Regulator y gene No RNA made RNA polymerase 3′ 5′ IacZ Active represso r Protein (a) Lactose absent, repressor active, operon off IacZ IacY IacA Iac I DNA mRN A Protein RNA polymerase Inactive represso r Allolacto se (inducer) (b) Lactose present, repressor inactive, operon on mRNA 5′ 3′ 5′ lac oper on lac I PermeaseTransacet ylase β-Galactosidase

© 2014 Pearson Education, Inc. Concept 15.2: Eukaryotic gene expression is regulated at many stages ▪_______________________________________________

© 2014 Pearson Education, Inc. Figure 15.6 Signa l NUCLEUS Chromatin Chromatin modification: DNA unpacking involving histone acetylation and DNA demethylation DNA Gen e RNAExo n Gene available for transcription Transcriptio n Primary transcript Intro n RNA processing Tail mRNA in nucleus Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Cap Protein processing, such as cleavage and chemical modification Active protein Transport to cellular destination Degradatio n of protein Cellular function (such as enzymatic activity, structural support)

© 2014 Pearson Education, Inc. Regulation of Chromatin Structure ▪__________________________________________ __________________________________________

© 2014 Pearson Education, Inc. Histone Modifications and DNA Methylation ▪__________________________________________ __________________________________________

© 2014 Pearson Education, Inc. Figure 15.7 Nucleosome Unacetylated histones Acetylated histones Histone tails

© 2014 Pearson Education, Inc. Epigenetic Inheritance ▪_________________________________________ _________________________________________

© 2014 Pearson Education, Inc. Figure 15.8 DNA Upstream Enhancer (distal control elements) Proximal control elements Transcripti on start site ExonIntro n Exon Prom oter Intro n Exon Poly-A signal sequence Transcript ion terminatio n region Dow n- strea m Tran scrip tion Exon Intro n Exon Poly-A signal Primary RNA transcript (pre-mRNA) 5′ Cleaved 3′ end of primary transcript Intron RNA mRNA RNA processing Coding segment 3′ 5′ 3′ Ca p UT R Sta rt cod on Sto p cod on UT R Pol y-A tail G PP P AAA … AA A

© 2014 Pearson Education, Inc. ▪________________________________________ ________________________________________ ▪________________________________________ Enhancers and Specific Transcription Factors

© 2014 Pearson Education, Inc. ▪_________________________________________ _________________________________________

© 2014 Pearson Education, Inc. Figure 15.9 Activation domain DNA DNA-binding domain

© 2014 Pearson Education, Inc. Figure 15.UN01 Chromatin modification Transcription RNA processing TranslationmRNA degradation Protein processing and degradation

© 2014 Pearson Education, Inc. Figure DN A Enhancer Distal control element Activators Promoter Gene TATA box

© 2014 Pearson Education, Inc. Figure DN A Enhancer Distal control element Activators Promoter Gene TATA box DNA- bending protein Group of mediator proteins General transcription factors

© 2014 Pearson Education, Inc. Figure DN A Enhancer Distal control element Activators Promoter Gene TATA box DNA- bending protein Group of mediator proteins General transcription factors RNA polymerase II RNA synthesis Transcription initiation complex

© 2014 Pearson Education, Inc. RNA Processing ▪_________________________________________ _________________________________________ _________________________________________ _________________________________________ ____ Animation: RNA Processing

© 2014 Pearson Education, Inc. Figure 15.UN02 Chromatin modification Transcription RNA processing Translation mRNA degradation Protein processing and degradation

© 2014 Pearson Education, Inc. Figure DNA Primary RNA transcript mRNA or Exons Troponin T gene RNA splicing

© 2014 Pearson Education, Inc. mRNA Degradation ▪______________________________________________ ______________________________________________

© 2014 Pearson Education, Inc. Initiation of Translation ▪__________________________________________ __________________________________________

© 2014 Pearson Education, Inc. Protein Processing and Degradation ▪__________________________________________ __________________________________________

© 2014 Pearson Education, Inc. Concept 15.3: Noncoding RNAs play multiple roles in controlling gene expression ▪_________________________________________ _________________________________________

© 2014 Pearson Education, Inc. Effects on mRNAs by MicroRNAs and Small Interfering RNAs ▪__________________________________________ __________________________________________ __________________________________________

© 2014 Pearson Education, Inc. Figure 15.UN03 Chromatin modification Transcription RNA processing Translation mRNA degradation Protein processing and degradation

© 2014 Pearson Education, Inc. Figure miRNA miRNA- protein complex Translation blockedmRNA degraded The miRNA binds to a target mRNA. 1 If bases are completely complementary, mRNA is degraded. If match is less than complete, translation is blocked. 2

© 2014 Pearson Education, Inc. ▪_________________________________________ _________________________________________

© 2014 Pearson Education, Inc. Making cDNA (complimentary DNA) for genetic studies and genetic engineering Fig. 16-5, p.245