BCHM 4116 1st Edition Lecture 24 Outline of Last Lecture I Genes Transcribed of Gene Expression II Transcription has 4 stages Outline of Current Lecture I Regulation of Transcription and Regulation of Gene Expression Cont II Gene Transcription in Eukaryotes Current Lecture Chapter 29 Transcription and Regulation of Gene Expression cont 3 Regulation of Transcription in Prokaryotes a Operator regulatory sequence lying adjacent to DNA being transcribed determines whether transcription takes place b Operons transcriptional control regions a set of related structural genes all organized in a contiguous linear array along chromosome i Expression of operon is determined by access of RNA pol to promoter and occupancy of operation by regulatory proteins influences this access ii Induction activates transcription from promoter repression prevents it c Attenuation regulates transcription after it has begun i Any regulation mechanism that manipulates transcription termination or transcription pausing to regulate gene transcription downstream 4 29 3 Gene Transcription in Eukaryotes d DNA of eukaryotes is wrapped around histones forming nucleosomes e Nucleosomes repress gene expression f Nucleosomes control gene expression by controlling transcriptional apparatus i 2 classes of transcriptional co regulators necessary to overcome nucleosome repression 1 Enzymes that covalently modify nucleosome histone proteins to loosen histone DNA interactions 2 ATP dependent chromatin remodeling complexes g Transcription in Eukaryotes h The three classes of RNA polymerase in eukaryotes RNA polymerases I II and III i RNA pol I localized to nucleolus transcribes rRNA ii RNA pol II transcribes protein encoding genes mRNA These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute iii RNA pol III transcribes tRNA genes rRNA genes other small RNAs iv ALL 3 RNA pol interact w their promoters via transcription factors 1 Transcription factors DNA binding proteins that recognize accurately initiate transcription at specific promoter sequences
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